This document provides an overview of various laboratory investigations that are important for oral and maxillofacial surgeons. It summarizes hematological investigations including complete blood count, coagulation tests, and biochemical investigations like lipid profile, glucose, kidney/liver function tests. It describes the purpose and clinical significance of these common blood tests and their normal ranges.

1. LABORATORY
INVESTIGATIONS IN ORAL AND
MAXILLOFACIAL SURGERY
PRESENTED BY
DR. AABY ABRAHAM
2ND YR POST GRADUATE
DEPT OF ORAL AND MAXILLOFACIAL
SURGERY
VSDC&H

2. CONTENTS
 INTRODUCTION
 HEMATOLOGICAL INVESTIGATIONS
 BIOCHEMICAL INVESTIGATIONS
 MICROBIOLOGIC INVESTIGATIONS
 CONCLUSION

3. INTRODUCTION
 The use of clinical laboratory tests constitutes an
important part of diagnostic evaluation of any patient,
both from general medical standpoint and in terms of
specific conditions that may be related to the etiology
of the pathologic process being considered by the oral
and maxillofacial surgeon.
 It is essential however that these tests be used
judiciously, not only because this will avoid
unnecessary cost and discomfort, but also because it
will avoid confusion that can be created by positive or
negative results of tests unrelated to the diagnosis
being considered.
 A good rule to follow is that every laboratory
procedure ordered should have a logical reason.

4.  SENSITIVITY indicates the ability of a test to
determine patients who have the disease; ie,
sensitivity equals the percentage of patients
known to have the condition who are detected
by the test.
 SPECIFICITY relates to the proportion of
cases without the disease who will have a
negative test; ie, specificity equals the
percentage of patients known not to have a
condition who yield negative test results.

5. HEMATOLOGIC
INVESTIGATIONS
 Hemoglobin
 Hematocrit
 Red blood cell count
 Red cell morphology
 White blood cell count
 Differential white cell count
 Sedimentation rate
 Red cell indices
 Mean corpuscular volume
 Mean corpuscular
hemoglobin
 Mean corpuscular
hemoglobin concentration
 Reticulocyte count
 Coagulation tests
 Prothrombin time
 Partial thromboplastin time
 Platelet count
 INR
 Bleeding time (DUKE)
 Clotting time
 Tourniquet test (RUMPEL
LEEDE)

6. HEMOGLOBIN (Hb)
 The amount of Hb indicates the oxygen carrying capacity of blood
 Normal value:
 Females: 12.1 to15.1 gm%
 Males: 13.8 to 17.2 gm%
 A decreased value is indicative of Anemia (<12gm%)
 Common cause of Anemia
 Vit B9 (folic acid), B2 (riboflavin), B12, Iron and Vit C deficiency
 Decreased absorption of Iron and Vit B6 as in sprue and
pernicious anaemia.
 Bone marrow depression
 Increased blood loss as in bleeding piles, gastric/duodenal
ulcers, heavy menstrual flow, haemoptysis and postpartum
bleeding are also other causes.

7. HEMATOCRIT
 Hematocrit is a measurement of
packed red cell volume in a volume
of blood.
 Normal value:
 Females: 37% to 47%
 Males: 40% to 52%
 Valuable in evaluating
Polycythemia, Anemia and blood
loss.
 Rule of thumb: 4 point loss or gain
in Hematocrit is roughly equal to the
loss or gain of one unit of blood
(500 ml).
 Prior to the blood transfusion,
hematocrit levels are measured to

8. RED BLOOD CELL COUNT
 RBC Count provides a gross estimate of
body’s oxygen carrying capacity and is used in
figuring red cell indices
 Normal value:
 Females: 4.5 and 5.5 million cells/mm3
 Males: 4.5 to 6.2 million cells/mm3
 Increased RBC:- Polycythemia and extreme
dehydration
 Decreased RBC: Anemia, Pellagra,
Hemorrhage, Liver Disease

9. RED CELL MORPHOLOGY
 Peripheral smear stained with polychrome stain such
as Wright’s stain can give vast amount of information
of the RED CELLS.
Some terms used to
describe alterations in
size, shape and staining
characteristics:-
•Normocytic
•Macrocytic
•Microcytic
•Normochromic
•Hyperchromic
•Hypochromic
•Anisocytosis
•Poikilocytosis
•Target cells
•Sickle cells
•Burr cells
•Nucleated RBC
•Polychromasia

10. WHITE BLOOD CELL COUNT
 WBC count is essential in dealing with
infections or other diseases such as leukemia.
 Normal count: 4000 to 11000 cells/microlitre
 Leukocytosis – above 11000
 Leukopenia – below 4000
 Agranulocytosis – below 500

11. DIFFERENTIAL COUNT
 It is a cell type distribution of total WBC
 On a well prepared Wright’s stained slide, 100 to 200 WBC are
counted and percent of each kind is reported.
 Normal distribution:
 Neutrophils: 50% to 70 %
 Lymphocytes: 25% to 40%
 Monocytes: 3% to 8%
 Eosinophils: 1% to 4%
 Basophils: 0% to 1%
 SHIFT TO LEFT : means increase in immature Neutrophils –
acute infection
 SHIFT TO RIGHT: means increase in number of mature
Neutrophils - suppression of bone marrow activity, as a hematological
sign specific for pernicious anemia and radiation sickness

12. RED CELL INDICES
 Useful for measuring the size, shape and
hemoglobin content of the RBC
 Based on hematocrit, hemoglobin and RBC
count.
 Various indices
 MCV
 MCV
 MCHC

13. MEAN CORPUSCULAR VOLUME
(MCV)
 It is the average volume of a red blood cell
 Calculation:
MCV=(HCT x 10)/ RBC
 Normal range: 82 to 98 cuµ ( normocytic
anemias fall in this range)
 Microcytic < normal range> Macrocytic

14. MEAN CORPUSCULAR
HEMOGLOBIN (MCH)
 Determined by hemoglobin content and RBC
 Estimates the average mass
of hemoglobin per red blood cell.
 Calculation:
MCH = (Hb x 10)/ RBC
 Normal range: 27 to 32 µµg
 Microcytic < Normal range > Macrocytic

15. MEAN CORPUSCULAR
HEMOGLOBIN
CONCENTRATION (MCHC)
 Estimates the average amount of hemoglobin
in 100 ml of packed red blood cells
 Uses Hb and Hematocrit
 Calculation:
MCHC = (Hb x 100)/ HCT
 Normal range: 32 to 38 gm/100ml
 Increased in: Hereditary Spherocytosis
 Decreased in : Microcytic anemia

16. ERYTHROCYTYE
SEDIMENATION RATE (ESR)
 ESR is the rate at
which red blood cells
sediment in a period of
one hour.
 It is a non-specific test
 NORMAL VALUES:
 Females: 0 to 20
mm/hr
 Males: 0 to 10 mm/hr
•The ESR is increased in
inflammation, pregnancy, anemia, autoimmune disorders (such
as rheumatoid arthritis and lupus), infections, some kidney
diseases and some cancers (such as lymphoma and multiple
myeloma).
•The ESR is decreased in
polycythemia, hyperviscosity, sickle cell anemia, leukemia, low

17. RETICULOCYTE COUNT
 Reticulocytes are immature RBC.
 Normal range: 0.5% to 1.5% of RBC.
 It is increased when RBC formation is increased and
are associated with treatment of various Anemia and
blood loss.
 It is decreased in:
 chemotherapy
 aplastic anemia
 pernicious anemia
 bone marrow malignancies
 problems of erythropoietin production
 various vitamin or mineral deficiencies (iron, vitamin
B12, folic acid)

18. PROTHROMBIN TIME (PT)
 Measures: extrinsic and common pathways
 It is reported in seconds and or percentages.
 If reported in seconds:
 the lab gives the PT over the control time
 Normal range: 11 to 15 seconds
 If reported in percentages:
 Normal range – 70% to 100%
 Prolonged in:-
 deficiency of Factors 1,2,5,7and 10
 Anticoagulant therapy
 Cirrhosis
 Obstructive jaundice
 Colitis
 Celiac disease
 Sprue
 Salicylate therapy

19. PARTIAL THROMBOPLASTIN
TIME (PTT)
 Measures the intrinsic and
common pathways
 Normal value are between
25 to 40 seconds.
 Prolonged in
 Deficiency of factors 8,9,11
and 12 in the intrinsic
pathway and factors 1,2,5
and 10 in the common
pathway.
 Undergoing heparin therapy

20. PLATELET COUNT
 Platelets have no cell nucleus: they are
fragments of cytoplasm that are derived from
the megakaryocytes of the bone marrow, and
then enter the circulation. Their main function is
hemostasis.
 Platelet concentration is measured either
manually using a hemocytometer, or by placing
blood in an automated platelet analyzer
using electrical impedance, such as a Coulter
counterDYNAMIC
S OF
PLATELET
S
Adhesio
n
Activatio
n
Aggregation
Wound
repair

21. INTERNATIONAL NORMALIZED
RATIO (INR)
 The result (in seconds) for a prothrombin time performed on a
normal individual will vary according to the type of analytical
system employed. This is due to the variations between
different types and batches of manufacturer's tissue factor
used in the reagent to perform the test. The INR was devised
to standardize the results.
INR =
(PTTEST/PTNORMAL)ISI
 Each manufacturer assigns an ISI value (International
Sensitivity Index) for any tissue factor they manufacture. The
ISI value indicates how a particular batch of tissue factor
compares to an international reference tissue factor. The ISI
is usually between 0.94 and 1.4 for more sensitive and 2.0-
3.0 for less sensitive thromboplastins.

23. IN
R
 Used to monitor patients on warfarin or related
oral anticoagulant therapy.
 The normal range
 for a healthy person not using warfarin = 0.8 to 1.2,
 for people on warfarin therapy = 2.0–3.0 is usually
targeted
 Although the target INR may be higher in
particular situations, such as for those with
a mechanical heart valve
 If the INR is outside the target range
 High INR indicates a higher risk of bleeding
 Low INR suggests a higher risk of developing a clot.

24. HEREDITARY CAUSES OF
ABNORMAL BLEEDING
TIME
ACQUIRED CAUSES OF
ABNORMAL BLEEDING
TIME
•von Willebrand disease
•Glanzmann
thrombasthenia
•Bernard-Soulier
syndrome
•Connective-tissue
diseases.
•Vitamin C deficiency
•Alcohol intoxication
•Uremia
•Liver failure
•Leukemias
•Myelodysplastic
syndrome

25.  It measures
intrinsic and
common pathways.
 Normal range: 4 to
10 min
 Prolonged in factor
deficiencies
 Used in
management of
heparin therapy.

26. TOURNIQUET TEST (RUMPEL-
LEEDE)
 Crude test to study the capillary-platelet interphase.
 Clinical diagnostic method to determine a
patient's haemorrhagic tendency.
 A BP cuff is placed on the upper arm and left inflated for 5
min halfway between patient’s systolic and diastolic blood
pressures.
 After removing the cuff,
 the number of petechiae in a 5 cm diameter circle of the area under
pressure is counted.
 Normally less than 15 petechiae are seen. 15 or more petechiae
indicate capillary fragility
 occurs due to
 poor platelet function
 bleeding diathesis or thrombocytopenia

27. BLOOD
CHEMISTRY
 Includes:
 Total protein
 Albumin
 Calcium
 Phosphorous (inorganic)
 Lipid profile
 Glucose
 Uric acid
 Creatinine
 Alkaline phosphatase
 Lactic dehydrogenase
 Glutamin oxaloacetic
transaminase (SGOT)
 Glutamic pyruvic
transaminase (SGPT)
SMA 12 (Sequential Multiple Analyzer-12) is a biochemical
survey of 12 blood constituents that help in screening
patients for a variety of diseases

28. TOTAL
PROTEIN
INCREASED
• Paraproteinaemia
• Hodgkin's lymphoma
• Leukaemia
• condition causing an increase
in immunoglobulins
• Dehydration
DECREASED
• Hepatocellular disease
• Malabsorption disease
• Starvation
• Acute infection
• Burns
Normal value:
6 to 8gm/100ml of serum.

29. ALBUMI
N Increase in
value
• Dehydration
• Acute infections
• Burns
• Stress from surgery
• Cardiac arrest
Decrease in value:
• Kidney diseases –
Nephrosis, chronic
glomerulonephritis
• GIT diseases – Ulcerative
colitis and protein losing
enteropathy
• Liver diseases – Laennec’s
Cirrhosis and hepatocellular
damage secondary to
hepatitis
MOLECULAR "TAXI"

30. CALCIUM
Increased
• levels seen in
excessive osteolysis
• Hyperparathyroidis
m
• Malignancy with
bone metastasis
Decreased levels
• Hypoparathyroidis
m
• Tetany
• Hypoalbuminemia
• Acute pancreatitis
• Renal failure
• Starvation
Since one third to one half of serum
calcium is bound to protein, the total
protein and serum albumin levels must be
known before serum calcium levels can be

31. Increase levels:
• Hypoparathyroidism
• Pseudohypoparathyroidism
• Secondary
hyperparathyroidism caused
by chronic renal failure and
metabolic acidosis.
Decreased levels:
• Primary hyperparathyroidism
• Vitamin D deficiency
• Malabsoprtion diseases
• Chronic antacid usage
PHOSPHOROUS
(INORGANIC)

32. LIPID
PROFILE

33. CHOLESTEROL
 Normal cholesterol
value: 150 to 300
mg/100ml

34. TRIGLYCERIDES
 Normal value: 30 to 150mg/100ml of blood
 Increase:
 Congenital hyperlipidemia
 Nephrotic syndrome
 Diabetes mellitus
 Myocardial infarction

35. LIPOPROTEINS
 Lipoproteins are
complex particles
composed of
multiple proteins
which transport
all fat molecules
(lipids) around the
body within the
water outside cells.
 They are typically
composed of 80-
100 proteins per
particle.

36. HIGH DENSITY
LIPOPROTEIN (HDL)
 HDL particles remove fat molecules from cells
which need to export fat molecules. The fats
carried include cholesterol, phospholipids,
and triglycerides; amounts of each are quite
variable.
 They can transports almost 100 fat molecules
/particle
 Increasing concentrations of HDL particles are
strongly associated with decreasing
accumulation of atherosclerosis within the
walls of arteries.
 Normal range: 40-50 mg/dL

37. Increase in HDL is seen
in :-
 Decreased intake of simple
carbohydrates.
 Aerobic exercise
 Weight loss
 Magnesium supplements raise HDL-C.
 Addition of soluble fiber to diet
 Consumption of omega-3 fatty acids such
as fish oil or flax oil
 Consumption of pistachio nuts
 Increased intake of cis-unsaturated fats
 Consumption of medium-chain
triglycerides (MCTs) such as caproic
acid, caprylic acid, capric acid, and lauric
acid.
 Removal of trans fatty acids from the diet
RECREATION
AL DRUG:
HDL can also
be increased
by Smoking
Cessation and
mild to
moderate
alcohol intake

38. LOW DENSITY LIPOPROTEIN
(LDL)
 LDL delivers fat molecules to the cells and can
drive the progression of atherosclerosis if they
become oxidized within the walls of arteries. The
lipids carried include all fat molecules
with cholesterol, phospholipids,
and triglycerides dominant
 Can transport 3,000 to 6,000 fat
molecules/particle.
 Normal range: less than 100 mg/dL

39. INCREASE IN LEVELS OF LDL

40. VERY LOW DENSITY
LIPOPROTEIN (VLDL)r
Normal levels are from 2 to 30 mg/dL
 Very low-density lipoproteins transport
endogenous triglycerides, phospholipids, cholesterol,
and cholesteryl esters.
 It functions as the body's internal transport mechanism
for lipids.
 VLDL is assembled in the liver
from triglycerides, cholesterol, and apolipoproteins
 VLDL is converted in the bloodstream to low-density
lipoprotein (LDL) and intermediate-density lipoprotein
(IDL).
 VLDL particles have a diameter of 30-80 nm.
 VLDL transports endogenous products,

41. GLUCOSE
Normal glucose value: 65 to 110
mg/100ml
 Increased levels:
 Diabetes mellitus
 Cushing’s disease
 Acromegaly
 Stress that increases
endogenous output of
epinephrine and
glucocorticoids
 Pheochromocytoma
 Acute and chronic
pancreatitis
 Pancreatectomy
 Hyperthyroidism
 Hypoglycemic
medications
 Islet cell tumors of
pancreas
 Advanced cirrhosis or
hepatitis
 Early diabetes mellitus
 Addison’s disease
 Functional hypoglycemia
 Inborn errors of
metabolism – fructose
intolerance,
galactosemia and maple
syrup urine disease

42. URIC
ACID
 Increased levels:
 Gout
 Renal failure
 Diets high in
nucleoproteins
 Disease associated with
increased breakdown of
nucleoproteins such as
 Leukemia
 Mutiple myeloma
 Lymphoma
 Hemolytic anemia
 Decreased levels:
 Use of uricosuric drugs
 Wilson’s disease
 Use of ACTH
Normal uric acid value: 2.5 to 8mg/100ml

43. CREATINI
NE
 Increased value:
 Impaired kidney
function
 Muscle disease
 Serum creatinine
concentration is
inversely proportional to
GFR and is more
sensitive indicator of
this rate that the blood
urea nitrogen test.
 However some
creatinine is secreted
by the tubules and a
normal creatinine level
does not mean renal
filtration is not impaired

45. ALKALINE
PHOSPHATASE
NORMAL VALUE:
BETWEEN 44 TO 147
IU/L OR
0.73 TO 2.45
MICROKAT/L.

46. LACTATE
DEHYROGENASE
 LDH is found in
many tissues –
kidney heart,
skeletal muscle,
liver, RBC and
WBC and skin
 Increased value:
 Malignancies
 Inflammations
 Necrotic processes
 Infection
 MI remain elevated
for 10 to 14 days
 Pulmonary embolus
and pulmonary
infarctions
 Hepatitis
 Leukemia
 Lymphoma
 CHF

47.  The normal range of values for
AST (SGOT) is about 5 to 40
units per liter of serum.
 Found in tissues: heart, kidney
liver, skeletal muscle and
pancreas.
 Elevated in
 MI – 12 hours to 3 to 5 days
 Hepatitis (High)
 Cirrhosis and liver neoplasms
(Moderate)
 Muscular trauma and after surgery
ASPARTATE
TRANSAMINASE
catalyzes the
interconversion of
Aspartate & Αlpha-
ketoglutarate to
Oxaloacetate & Glutama
te

48.  The normal range of values for ALT (SGPT)
is about 7 to 56 units per liter of serum.
 The values are parallel to SGOT but are more
elevated in liver damage than myocardial
ALT catalyzes the transfer of an amino group from L-
alanine to α-ketoglutarate, the products of this
reversible transamination reaction being pyruvate and L-
glutamate.
L-alanine + α-ketoglutarate ⇌ pyruvate + L-glutamate

49. BLOOD UREA NITROGEN
 NORMAL VALUE: 10 to 20 mg/ml
 Increase:
 high protein diet
 associated with decrease in GFR
( ~ 30 % to 40% )
 pre and post azotemia
 Decreased:
 Advanced liver disease and low
protein diet.
 Syndrome of inappropriate
antidiuretic hormone.

50.  Breakdown product of hemoglobin.
 It is important in evaluating for
hemolytic anemia and hepatic
function.
 Measure in two forms
 Direct (conjugated) and Total
(conjugated and unconjugated)
 The difference between the two give
the amount of unconjugated bilirubin
(indirect)
 Normal value:
 <0.8mg of total bilirubin/100ml
BILIRUBI
N

51. HYPERBILIRUBINEMIA
 Mild increase
• Hemolysis
• Gilbert's syndrome
• Rotor syndrome
 Moderate increase
 Pharmaceutical
drugs
 Hepatitis
 Chemotherapy
 Biliary stricture
benign or
malignant
 Very high increase:
 Neonatal
hyperbilirubinaemi
a
 Unusually large
bile duct
obstruction
 Severe liver failure
with cirrhosis
 Crigler–Najjar
syndrome
 Dubin–Johnson
syndrome
 Choledocholithiasi
s
Jaundice may be
noticeable in
the sclera of the eyes at
levels of about 2 to 3
mg/dl

52. ACID PHOSPHATASE
 Normal value: 0 - 0.8 U/L
 Prostate is rich in AP
 Small amounts found in RBC, bone, kidney, liver
and spleen.
 Increase:
 Carcinoma of prostate has metastasized , especially
to bone
 Hyperparatyroidism
 Sickle cell anemia
 Multiple myeloma
 Gaucher’s disease

53. AMYLASE
 Normal value:
 23-85 units per liter (U/L), although some lab
results for amylase go up to 140 U/L.
 Increase:
 often associated with diseases of pancreas
 spasm resulting from use of opiates
 salivary gland disease
 bowel obstruction
 upper GIT surgery

54. Test is
started
with a
patient
fasting
overnight.
Blood and
urine
samples are
collected
prior to
glucose
load.
Glucose load is
given and
blood and urine
specimens are
taken at 30min,
1 hour, 11/2
hours, 2 hours
and 3 hours.
Normal value of glucose
• Fasting blood glucose level: 65 and 110
mg/100ml
• Fasting urine level: 0
• Post prandial blood glucose level:
• After 30 mins to 1 hour – upto 60mg/100ml
• After 2 hours - Gradually returns to fasting
levels or slightly below
• After 3 hours - steady value

55. GLYCATED
HEMOGLOBIN
 Sometimes referred to as
being Hb1c or HGBA1C) is a form
of hemoglobin that is measured primarily to
identify the three-month average plasma
glucose concentration.
 The test is limited to a three-month average
because the lifespan of a red blood cell is four
months (120 days).

56.  When blood glucose levels are
high, glucose molecules attach to the hemoglobin
in red blood cells. The longer hyperglycemia
occurs in blood, the more glucose binds to
hemoglobin in the red blood cells and the higher
the glycated hemoglobin.
 Once a hemoglobin molecule is glycated, it
remains that way. A buildup of glycated
hemoglobin within the red cell, therefore, reflects
the average level of glucose to which the cell has
been exposed during its life-cycle.
 Measuring glycated hemoglobin assesses the
effectiveness of therapy by monitoring long-term
serum glucose regulation.

58. CREATINE PHOSPHOKINASE
(CPK)
 Normal range: 22 to 198 U/L
 CPK found in heart muscle and brain
 Increase:
 Exercise increases the outflow of creatine kinase to the blood
stream for up to a week, and this is the most common cause of
high CK in blood.
 Furthermore, high CK in the blood may be related to high
intracellular CK such as in persons of African descent.
 medication such as Statins
 Endocrine disorders such as hypothyroidism
 MI
 Cerebral infarction
 Duchenne type muscular dystrophy
 Malignant hyperthermia

65. POTENZ HYDROGEN or
POWER OF HYDROGEN
(pH)
The slightly alkaline plasma pH of
7.4 (H+ 40 nmol/L) that is
maintained during health can be
accounted for the kidney’s ability to
generate an acidic urine (pH
typically 5–6), in which the net daily
excess of metabolic acid produced

66. PRESSURE OF DISSOLVED CO2
IN BLOOD (PCO2)
 Normal value arterial blood: 35 to 45 mm Hg
 Normal value venous blood: 41 to 51mm Hg
 Increases secondary to hypoventilation –
respiratory acidosis.
 Decreases secondary to hyperventilation –
respiratory alkalosis.

67. ACTUAL BICARBONATE
(HCO3)

68. CARBON DIOXIDE COMBINING
POWER
(CCP)
 CCP is an indicator of the state of the acid-
base balance.
 Normal value: 55 to 75ml of CO2/100ml of
plasma
 Acidosis is shown by a decrease in CO2
combining power.
 Alkalosis by an increase in CO2 combining
power

69. BASE EXCESS
 It represents the difference between
theoretical and actual total CO2 content of the
blood.
 Normal value: 0 with a range of ±2 mEq/L for
either arterial or venous blood
 Negative value: bicarbonate deficit
 Positive value: bicarbonate excess.

70. Po2 (Partial pressure of
Oxygen )
 Normal value for arterial blood : 80 to
100mm Hg
 Normal value for venous blood: 35 to 40 mm
Hg
 Decreased levels –
 hypoxia
 respiratory acidosis secondary to impaired
diffusion or shunting
 Normal levels of Po2 may be present in
metabolic acidosis and alkalosis

71. Oxygen saturation
 The amount of
oxygen bound to
hemoglobin
 Normal values
 Arterial: 95% to 98%
 Venous: 60 to 85%
An O2 sat of
90%
corresponds
to a PaO2 of
60 mmHg

72. THYROID FUNCTION TEST
 Thyroid function tests (TFTs) is a collective
term for blood tests used to check the function
of the thyroid.

73.  TFTs may be requested if a patient is thought to
suffer from
 hyperthyroidism (overactive thyroid)
 hypothyroidism (underactive thyroid)
 to monitor the effectiveness of either thyroid-
suppression or hormone replacement therapy
 conditions linked to thyroid disease, such as atrial
fibrillation and anxiety disorder.
 A TFT panel typically includes thyroid
hormones such as
 Thyroid-stimulating Hormone (TSH, Thyrotrophic)
 Thyroxin (T4)
 Triiodothyronine (T3) depending on local laboratory
policy.

74. Thyroid-stimulating
Hormone (TSH)
 Normal value: 0.4 to 4.0 mIU/L
 increased in hypothyroidism
 decreased in hyperthyroidism
 TSH levels may be suppressed by excess free T3
(fT3) or free T4 (fT4) in the blood
 TSH levels are considered the most sensitive marker
of thyroid dysfunction. They are however not always
accurate, particularly if the cause of hypothyroidism is
thought to be related to insufficient TRH secretion, in
which case it may be low or falsely normal. In such a
case a TRH stimulation test, in which TRH is given
and TSH levels are measured at 30 and 60-minutes.

75. Thyroxin (T4)
 elevated in hyperthyroidism
 decreased in hypothyroidism.
 elevated in pregnancy secondary to increased
levels of thyroid binding globulin.
 Total T4 is measured to see the bound and
unbound levels of T4
 Free thyroxine (fT4) is generally elevated
in hyperthyroidism and decreased
in hypothyroidism
 Normal values:
 Serum thyroxineT4: 4.6-12 ug/dl
 Free Thyroxine FT4: 0.7-1.9 ng/dl

76. Triiodothyronine (T3)
 Total T3 is generally elevated in
hyperthyroidism and decreased in
hypothyroidism
 Free triiodothyronine (fT3) is generally elevated
in hyperthyroidism and decreased in
hypothyroidism.
 Normal value:
 Serum TriiodothyronineT3: 80-180 ng/dl
 Free Triiodothyronine lFT3: 230-619 pg/dl

77. THYROID ANTIBODY TESTS
 Lymphocytes make antibodies against their thyroid
that either stimulate or damage the gland.
 Two common antibodies that cause thyroid problems
are directed against thyroid cell proteins:
 thyroid peroxidase
 thyroglobulin.
 Measuring levels of thyroid antibodies may help
diagnose the cause of the thyroid problems. For
example:-
 positive anti-thyroid peroxidase and/or anti-thyroglobulin
antibodies in a patient with hypothyroidism make a
diagnosis of Hashimoto’s thyroiditis.
 If the antibodies are positive in a hyperthyroid patient, the
most likely diagnosis is autoimmune thyroid disease.

78. THYROGLOBULIN
 Thyroglobulin (Tg) is a protein produced by
normal thyroid cells and also by thyroid cancer
cells. It is not a measure of thyroid function
and it does not diagnose thyroid cancer when
the thyroid gland is still present.
 It is used most often in patients who have had
surgery for thyroid cancer in order to monitor
them after treatment.

79. NON-BLOOD TESTS
 RADIOACTIVE IODINE UPTAKE
 The thyroid gland must pull a large amount of iodine out
from the blood stream in order for the gland to make an
appropriate amount of T4.
 Therefore, this activity can be measured by having an
individual swallow a small amount of iodine, which is
radioactive.
 By measuring the amount of radioactivity that is taken up
by the thyroid gland (radioactive iodine uptake, RAIU)
determine whether the gland is functioning normally. A
very high RAIU is seen in individuals whose thyroid gland
is overactive (hyperthyroidism), while a low RAIU is seen
when the thyroid gland is underactive (hypothyroidism

80. MICROBIOLOGY
INVESTIGATIONS

81. HI
V
 HIV tests are used to detect the presence of the human
immunodeficiency virus (HIV), the virus that causes Acquired
Immunodeficiency Syndrome (AIDS), in serum, saliva, or urine.
 The window period is the time from infection until a test can
detect any change. The average window period with HIV-1
antibody tests is 25 days for subtype B. Most people develop
detectable antibodies approximately 30 days after infection,
although some seroconvert late
 Antigen testing cuts the window period to approximately 16
days and Nucleic Acid Testing (NAT) further reduces this period

82. ANTIBODY
TESTS
 Enzyme-linked
Immunosorbent
Assay (ELISA)
 Western blot
 Rapid or point-of-care
tests ANTIGEN TESTS
• p24 antigen test
• Nucleic Acid-based
Test (NAT)

83. IMPORTANCE OF HIV TEST
India is estimated to have around 1.16 lakh annual new HIV infections
among adults and around 14,500 new HIV infections among children in
2011.
Information is useful for
prophylaxis, medical
management and
treatment of HIV and
related illnesses.
To assure blood
safety and
donation safety.
To assess the
efficacy of targeted
intervention in a
defined cohort.
To monitor trends of
epidemic (sentinel
surveillance etc.).
Identification of
asymptomatic individuals
(practising high risk
behaviour). To plan
personal and family's
future if the result is
positive.
To motivate for behaviour
modification through
counselling amongst those
who test negative and who
practise high risk
behaviours.
To induce behaviour
change and prevent
transmission by
counselling in those
who test positive.
To diagnose clinically
suspected cases.
For peace of mind
of individuals
practising high risk
behaviour

84. CD4 T-CELL COUNT
It is not an HIV test
• Does not check for the
presence of HIV.
• It is used to monitor immune
system function in HIV-
positive people.
• Women tend to have
somewhat lower counts than
men.
Low CD4 T-cell
counts are
associated with a
variety of conditions
• Sepsis
• Tuberculosis,
Coccidiomycosis
• Burns
• Trauma
• Intravenous injections
of foreign proteins
• Malnutrition
• Over-exercising
• Pregnancy
• Normal daily variation
• Psychological stress
• Social isolation
Declining CD4 T-cell counts are
considered to be a marker of
progression of HIV infection.
A normal CD4 count can range
from 500 cells/mm3 to 1000
cells/mm3.
In HIV-positive people, AIDS is
officially diagnosed when the count
drops below 200 cells/μL or
when certain opportunistic
infections occur.

85. HEPATITIS B VIRUS (HBV)
 The main uses for HBV tests include:
 To determine whether acute signs and symptoms are
due to HBV infection
 two tests, hepatitis B surface Ag and hepatitis B core
antibody IgM, may be performed as part of an acute
viral hepatitis panel along with tests for hepatitis A
(HAV) and hepatitis C (HCV) to determine which virus
may be causing the infection.
 To diagnose chronic HBV hepatitis
 To monitor chronic hepatitis B infection and its
treatment
 To detect previous exposure to hepatitis B, in a
person who is immune compromised.

86. TEST DESCRIPTION COMMENT
Hepatitis B
surface antigen
(HBsAG)
Detects protein
that is present on
the surface of the
virus
•Earliest indicator of acute
hepatitis B
•Primary way of identifying those
with chronic infections, including
"HBV carrier" state.
Hepatitis B
surface antibody
(anti-HBs)
Detects antibody
produced in
response to HBV
surface antigen
Used to detect previous exposure
to HBV
Total anti-
hepatitis B core
(anti-HBc, IgM
and IgG)
Detects both IgM
and IgG antibodies
to hepatitis B core
antigen
•IgM antibody is the first antibody
produced after infection with HBV
•IgG antibody is produced in
response to the core antigen later
in the course of the infection and
usually persists for life.
INITIAL TESTING

87. FOLLOW-UP AFTER INITIAL
TESTSTest Description Comments
Anti-hepatitis B core
(anti-HBc), IgM
Detects only the IgM
antibody to the hepatitis B
core antigen
Used to detect acute
infections
Hepatitis B e-antigen
(HBeAG)
Detects protein produced
and released into the blood
•marker of ability to spread
the virus to other people
(infectivity)
•it may also be used to
monitor the effectiveness of
treatment.
Anti-hepatitis B e
antibody (Anti-HBe)
Detects antibody produced
by the body in response to
the hepatitis B "e" antigen
To monitor acute infections in
those who have recovered
from acute hepatitis B
infection; anti-HBe will be
present along with anti-HBc
and anti-HBs.
Hepatitis B viral DNA Detects hepatitis B viral
genetic material in the
blood
A positive test indicates that
the virus is multiplying in a
person's body and that

88. VENEREAL DISEASE
RESEARCH LABORATORY
TEST (VDRL)
 The VDRL test is used to screen
for syphilis.
 Assess response to therapy
 To detect central nervous
system involvement, and as an
aid in the diagnosis of congenital
syphilis.
 The basis of the test is that an
antibody produced by a patient
with syphilis reacts with an
extract of ox heart
(diphosphatidyl glycerol). It
therefore detects anti-cardiolipin
antibodies (IgG, IgM or IgA),
visualized through foaming of the
OTHER TESTS
Fluorescent treponemal
antibody-absorption
(FTA-ABS) test
T. pallidum
hemagglutination
assays (TPHA)
Microhemagglutination
assay (MHA-TP).

89. ANTI-STREPTOLYSIN O
 ASO or ASLO is the antibody
made against streptolysin O,
an immunogenic, oxygen-
labile streptococcal hemolyti
c exotoxin produced by
most strains of group A and
many strains of groups C
and
G Streptococcus bacteria.
The main function of
streptolysin O is to cause
hemolysis
 Since these antibodies are
produced as a delayed
antibody reaction, there is no

90.  Acceptable values, where there is no clinical
suspicion of rheumatism are as follows:
 Adults: less than 200 units
 Children: less than 400 units
 Antibody levels begin to rise after 1 to 3 weeks
of strep infection, peaks in 3 to 5 weeks and
falls back to insignificant levels in 6 months
False positives can result
from liver
disease and tuberculosis

91. POLYMERASE CHAIN
REACTION
 Developed by Kary Mullis in 1983
 PCR is a technique used in molecular biology
to amplify a single copy or a few copies of a
segment of DNA across several orders of
magnitude, generating thousands of millions of
copies of a particular DNA sequence
 PCR amplifies a specific region of DNA strand
and the amount of amplified product is
determined by the available substrates in the
reaction which become limiting as the reaction
progresses.

92.  Basic PCR set up:
 DNA template that contains the DNA target region
to amplify
 DNA poymerase- to polymerise the new DNA
strand
 Two DNA primers
 Deoxynucleoside triphosphates
 Buffer solution
 Bivalent cations (Mg or Mn)
 Monovalent cations (K)

93.  Applications of PCR
 Selective DNA isolation from genomic DNA by
selective amplification of a specific region of DNA
 DNA sequencing to determine unknown PCR
amplified sequences
 PCR fingerprints: used to identify genetic
relationships between individuals
 Also used to determine evolutionary relationships
among organisms
 Forensic analysis

94. CARTRIDGE-BASED
NUCLEIC ACID
AMPLIFICATION TEST
 CBNAAT is a recently introduced polymerase
chain reaction (PCR) based method for
detection of TB. It also detects Rifampicin
resistance as it targets the rpoB gene of
Mycobacteria.
 CBNAAT is a Mycobacterium tuberculosis-specific
automated, cartridge based nucleic acid
amplification assay, having fully integrated and
automated amplification and detection using real-
time PCR, providing results within 100 minutes.
 It is a highly specific test as it uses 3 specific
primers and 5 unique molecular probes to target
the rpoB gene of M. tuberculosis, which is the
critical gene associated with rifampicin resistance.

95.  A Study Conducted By R Dewan et.al in 2015 using
CBNAAT on 100 subjects diagnosed with HIV who
presented to the chest and TB centre of Lok Nayak
hospital with productive cough for 2 weeks and/or
chest X-ray findings suggestive of pulmonary
tuberculosis detected 40 patients with pulmonary
tuberculosis.
 Further, rifampicin resistance was detected in 10
patients of which 9 turned out to be MDRTB by LPA.
 Both these results were available within 2 hours. Past
studies on drug resistance have shown that rifampicin
resistance is seldom detected alone and 90 % of
rifampicin resistant patients turn out to be MDR-TB.
 In the present study, 9/10 rifampicin resistant samples
demonstrated resistance to isoniazid also.
 Hence CBNAAT can be a useful test for screening for

96. IMMUNOHISTOCHEMISTRY
 IHC involves the process of selectively
imaging antigens in cells of a tissue section by
exploiting the principle of antibodies binding
specifically to antigens in biological tissue.
 It is widely used in the diagnosis of abnormal
cells such as those found in cancerous
tumours.
 IHC measures protein expression using
specifically labelled antibodies that can bind to
the proteins of interest.

97.  The antibody is mixed with cellular
components of the tumour and
after a set amount of time the
mixture is rinsed and only those
antibodies attached to their target
proteins will remain
 The presence of antibodies can be
detected by viewing the sample
under a microscope because areas
containing bound antibodies will
appear a different colour than
areas lacking antibodies.
 Sample with more protein will bind
more antibodies and hence appear
darker than those areas lacking
antibodies.
 This allows the test to reveal not
only whether a protein is present
but also the relative amount of the
protein.
 Test results are based on the

98. WOUND CULTURE
 A bacterial wound culture is primarily used, along with
a Gram stain and other tests, to help determine whether
a wound is infected and to identify the bacteria causing
the infection.
 If a culture reveals that a wound is
infected, susceptibility testing is done to determine
which antibiotic will inhibit the growth of the bacteria
causing the infection.
 A wound culture may also sometimes be ordered for an
individual who has undergone treatment for a wound
infection to determine whether the treatment was
effective. It may also be ordered at intervals for a person
who has a chronic infection to help guide further
treatment.

99. When is it done?
 This test is primarily ordered when a healthcare
practitioner suspects that a wound is infected or to
identify the organisms causing the infective
process so that targeted antimicrobial therapy
could be implemented.
 Some signs and symptoms of an infected wound
may include:
 A wound that is slow to heal
 Heat, redness and swelling at the site
 Tenderness at the site
 Drainage of fluid or pus
 Fever

100. C-REACTIVE PROTEIN
 C-reactive protein (CRP) is an annular (ring-
shaped), Pentameric protein found in blood
plasma, whose levels rise in response
to inflammation.
 It is an acute-phase protein of hepatic origin
 Increases following interleukin-6 secretion
by macrophages and T cells.
 Physiological role:
 bind to LYSOPHOSPHATIDYLCHOLINE expressed
on the surface of dead or dying cells (and some types
of bacteria) in order to activate the complement
system via the C1Q complex

101. Function of CRP
 After binding to the phosphocholine on the
cells it activates the complement system,
promoting phagocytosis by macrophages
(opsonin mediated phagocytosis).
 CRP rises within two hours of the onset of
inflammation.
 Upto 50,000 fold
 peaks at 48 hours
 Half life is 18 hours

102. DIAGNOSTIC USE OF CRP
 Marker of inflammation
 Measuring and charting CRP values can prove
useful in determining disease progress or the
effectiveness of
treatments. ELISA, immunoturbidimetry, nephelom
etry, rapid immunodiffusion, and
visual agglutination are all methods used to
measure CRP.

103. HIGHER LEVELS ARE
FOUND IN
Late
pregnant
women
Mild
inflammation and
viral infections
(10–40 mg/L)
Active
inflammation
Bacterial
infection
(40–
200 mg/L)
Severe bacterial
infections and
Burns (>200 mg/L
)
Normal concentration in healthy human serum: 5 to
10 mg/L which increases with age.

104. CONCLUSION
 The economic, medical and societal benefits
of in vitro diagnostic tests are often
overlooked, despite the fact that these tests:
 improve patient care
 contribute to protecting consumer health
 help to limit healthcare spending, which is a major
economic issue in every country throughout the
world.

105. IMPROVE PATIENT CARE
 Detecting and diagnosing disease more
rapidly and at an earlier stage, even before
symptoms occur
 Choosing more targeted, effective, and often
less invasive treatments,
 Monitoring treatment to effectively manage
chronic diseases
 Estimating patient prognosis.

106. PROTECTING CONSUMER
HEALTH
 Companies in the food-processing,
pharmaceutical and cosmetics industries use
specific diagnostic tests to check the
microbiological quality of their products and
the environment in which they are
manufactured.
 These quality control tools help to ensure the
safety of products such as infant formula or
vaccines, thus contributing to protect
consumer health.

107. POSITIVE IMPACT ON HEALTHCARE
COSTS
 Diagnostics play a major role in controlling
healthcare spending, as an appropriate test
carried out in good time can reduce the risk of
trial-and-error treatment or over-prescription.
 Only 1% of funds allocated to healthcare around
the world is spent on diagnostic tests, yet they
underpin a majority of medical decisions.
 The cost of in vitro tests is generally very low
compared with:
 the medical service provided,
 the savings generated by shortening the time taken to
provide treatment and the duration of hospital stays.

108. REFERENCES
 Oral and Maxillofacial Surgery –Daniel Laskin
 Practical Medicine – P.J Mehta
 Clinical Medicine – Kumar and Clark
 Pathologic basis of diseases- Robbins and Cotran
 Basic laboratory procedures in clinical bacteriology – WHO
 Guideline for good clinical laboratory practices (GCLP) – Indian council of medical
research, New Delhi.
 Kumar A, Srivastava U. Role of routine laboratory investigations in preoperative
evaluation. Journal of anaesthesiology, clinical pharmacology. 2011 Apr;27(2):174.
 Carson JL, Kleinman S, Silvergleid AJ, Tirnauer JS. Indications and hemoglobin
thresholds for red blood cell transfusion in the adult. U: UpToDate, Silvergleid AJ, ur.
UpToDate [Internet]. Waltham, MA: UpToDate. 2016.
 Stathopoulos P, Igoumenakis D, Shuttleworth J, Smith W, Ameerally P. Predictive
factors of hospital stay in patients with odontogenic maxillofacial infections: the role
of C-reactive protein. British Journal of Oral and Maxillofacial Surgery. 2017 May
1;55(4):367-70.
 Arterial blood gas interpretation: the basics – David C Chung
 Delgado-Rodríguez M, Medina-Cuadros M, Gómez-Ortega A, Martínez-Gallego G,
Mariscal-Ortiz M, Martinez-Gonzalez MA, Sillero-Arenas M. Cholesterol and serum
albumin levels as predictors of cross infection, death, and length of hospital stay.
Archives of surgery. 2002 Jul 1;137(7):805-12.

109.  Zambouri A. Preoperative evaluation and preparation for anesthesia and
surgery. Hippokratia. 2007 Jan;11(1):13.
 Haug RH, Reifeis RL. A prospective evaluation of the value of preoperative
laboratory testing for office anesthesia and sedation. Journal of oral and
maxillofacial surgery. 1999 Jan 1;57(1):16-20.
 Quach S, Brooke AE, Clark A, Ellison SJ. Blood investigations prior to oral
surgery for suspected alcohol-induced coagulopathy. Are they necessary?.
British dental journal. 2015 Aug 14;219(3):121-3.
 Aguilera IM, Vaughan RS. Calcium and the anaesthetist. Anaesthesia. 2000
Aug 17;55(8):779-90.
 Dewan R, Anuradha S, Khanna A, Garg S, Singla S, Ish P, Agarwal S. Role
of cartridge-based nucleic acid amplification test (CBNAAT) for early
diagnosis of pulmonary tuberculosis in HIV. Journal, Indian Academy of
Clinical Medicine. 2015 Apr;16(2):115.
 Jacobs Jr DR, Hebert B, Schreiner PJ, Sidney S, Iribarren C, Hulley S.
Reduced Cholesterol Is Associated with Recent Minor Illness The CARDIA
Study. American journal of epidemiology. 1997 Oct 1;146(7):558-64.
 da Silva LC, de Assunção Oliveira AC, dos Santos JA, de Santana Santos
T. Criteria for the request of preoperative tests among oral and maxillofacial
surgeons. Journal of Cranio-Maxillofacial Surgery. 2012 Oct 31;40(7):604-
7.

110.  Lascari AD. The erythrocyte sedimentation rate. Pediatric Clinics of North America. 1972 Nov
30;19(4):1113-21.
 Olshaker JS, Jerrard DA. The erythrocyte sedimentation rate. The Journal of emergency
medicine. 1997 Nov 1;15(6):869-74.
 Pang M, Fang Y, Chen S, Zhu X, Shan C, Su J, Yu J, Li B, Yang Y, Chen B, Liang K.
Gypenosides Inhibits Xanthine Oxidoreductase and Ameliorates Urate Excretion in Hyperuricemic
Rats Induced by High Cholesterol and High Fat Food (Lipid Emulsion). Medical science monitor:
international medical journal of experimental and clinical research. 2017;23:1129.
 McCann WS. A study of the carbon dioxide-combining power of the blood plasma in experimental
tetany. Journal of Biological Chemistry. 1918 Sep 1;35(3):553-63.
 Femlak M, Gluba-Brzózka A, Ciałkowska-Rysz A, Rysz J. The role and function of HDL in
patients with diabetes mellitus and the related cardiovascular risk. Lipids in health and disease.
2017 Dec;16(1):207.
 Grundy SM. Management of hyperlipidemia of kidney disease. Kidney international. 1990 Mar
1;37(3):847-53.
 Peng TC, Wang CC, Kao TW, Chan JY, Yang YH, Chang YW, Chen WL. Relationship between
hyperuricemia and lipid profiles in US adults. BioMed research international. 2015 Jan 5;2015.
 www.mayoclinic.com
 www.webmd.com
 www.wikipedia.com