Lab Investigation are the crucial part of oral and maxllofacial surgery as it predetermined the outcome of any major or minor surgery and helps in the proper treatment planning.

1. LAB INVESTIGATIONS IN OMFS
PRESENTED BY:– Dr. Mohd Akmal
MODERATED BY:– Dr. Ishita

2. CONTENTS
• INTRODUCTION
• HEMATOLOGICAL INVESTIGATIONS
• BIOCHEMICAL INVESTIGATIONS
• MICROBIOLOGICAL INVESTIGATIONS
• CONCLUSION

3. INTRODUCTION
• Laboratory tests are an invaluable aid to the practicing oral &
maxillofacial surgeons.
• In conjunction with a thorough history and physical examination,
laboratory tests aid in the diagnosis of various diseases.
• Allow the precise preoperative and postoperative management of
patients with systemic disease.
• In addition, patients without overt disease can be screened before
procedures that carry potentially serious complications, such as
general anaesthesia , are begun.

4. HAEMOTOLOGICAL INVESTIGATIONS
• 1. CBC
• 2. COAGULATION TESTS
• 3. CALCIUM
• 4. PHOSPHORUS
• 5. GLUCOSE
• 6. GLYCATED HAEMOGLOBIN

5. COMPLETE BLOOD COUNT (CBC)
• 1.Haemoglobin
• 2.Total leukocyte count
• 2.RBC Count
• 3.Red Cell Distribution Width (RDW)
• 4.Haematocrit / PCV
• 5.MCV
• 6.MCH
• 7.MCHC
• 8.WBC Count
• 9.DLC
• 10.Platelet Count

6. HAEMOGLOBIN CONCENTRATION
• Defines anaemia ( Hb<lower limit of normal adjusted for age and
gender)
New Born
16.5-19.5
g/dl
Children
11.2-16.5
g/dl
Males
14.0-18.0
g/dl
Females
12.0-16.0
g/dl

7. RED BLOOD CELL/ ERYTHROCYTE COUNT
• Children - 4.5-5.1 million/mm3
• Males - 4.6-6.2 million/mm3
• Females - 4.2-5.4 million/mm3

8. Low RBC
Count
• Hypoprolioferative anaemias e.g. Iron, Vitamin B12 and Folate deficiencies.
• Aplasias e.g. Idiopathic or drug-induced
• Parvovirus B19 infection-induced red cell aplasia resulting in transient marked anaemia.
High RBC
Count
• Polycythemia vera

9. HAEMATOCRIT OR PCV
• It is the ratio of the volume of red blood cells to the total volume of
blood.
• Men : 47%
• Women : 42%
• High PCV - Polycythemia
• Low PCV - Anaemia

10. MEAN CORPUSCULAR VOLUME (MCV)
• Measurement of RBC size.
• MCV = Normal PCV per 100 ml blood X 10 fL
RBC count in million/microL
• Normal value:- 80-96 femtolitres
• Smaller size RBC:- Microcytes
• Larger size RBC:- Macrocytes

11. Increase in MCV: Large (macrocytic) RBC—macrocytic anaemia
as in vitamin B12 or folic acid deficiency.
Decrease in MCV: Smaller (microcytic) RBC—iron deficiency and
thalassaemia.

12. MEAN CORPUSCULAR HEMOGLOBIN
• Macrocytosis • Microcytosis e.g.Iron
deficiency anaema
HIGH LOW
Average amount of hemoglobin in a single RBC in picogram
MCH = Hemoglobin in gm% X 10 pg
RBC count in million/cumm
Range – 28 -32 pg

13. MEAN CORPUSCULAR HEMOGLOBIN
CONCENTRATION
• Hemoglobin concentration in a single RBC.
• MCHC = Hb in gm % X 100
• PCV per 100 ml blood
• RBC's can not hold more than 37 g/dL of haemoglobin.
• Increase in MCHC: Hyperchromic RBC—hereditary spherocytosis.
• Decrease in MCHC: Hypochromic RBC—iron deficiency and
thalassaemia.

15. TOTAL LEUCOCYTE COUNT
• Increased • Decreased
Acute infections, Uremia,
Steroids,Hemorrhage,Leukemia
Radiation,Aplastic anemia, Infectious
mononucleosis,Septicemia

16. DIFFERENTIAL LEUCOCYTE COUNT
• PMN : 40-75 %
• Lymphocytes : 15-45 %
• Eosinophils : 1-6 %
• Basophils : 0-2 %
• Monocytes : 1-10 %

17. Neutrophils(PMNs) -
• Increased : Infections,Granulocytic leukemia,Surgery,Severe exercise
• Decreased :Viral infections, Aplastic anemia, Drugs, Radiations,
Dialysis.
Eosinophils -
• Increased : Allergic conditions, Parasitic infection, Collagen vascular
diseases, Addison diseases, Malignancy
• Decreased : Steroids, Stress ,ACTH excess, Cushing syndrome

18. Basophils-
• Increased : Polcythemia, Chronic Myeloid Leukemia
• Decreased : Steroids, Acute Rheumatic fever, Thyrotoxicosis
Lymphocytes-
• Increased : Viral infections, Tuberculosis, Mononucleosis
• Decreased : Stress,Uraemia, Steroids,AIDS
Monocytes-
• Increased : Monocytic leukemia, Chronic inflammation or
infection,Collagen diseases (RA, SLE), Protozoal infections, TB
• Decreased : Hypoplastic bone marrow

19. PLATELET COUNT
• Normal : 150000 – 400000/cumm
• Low count : Thrombocytopenia
• High count : Thrombocytosis

20. • Increased -
• Malignancy
• Post surgery
• Post splenectomy
• Rheumatoid arthritis (RA)
• Iron deficiency anemia
• Trauma
• Acute hemorrhage
• Decreased –
• Idiopathic thrombocytopenic
purpura (ITP)
• Marrow invasion or aplasia
• Hypersplenism
• DIC
• Cirrhosis
• Quinidine
• Massive transfusions
• Viral infections
• Infectious mononucleosis

21. COAGULATION TESTS -
1. Bleeding time
2. Clotting time
3. PT
4. PTT
5. INR

22. BLEEDING TIME -
• 1-6 minutes
• Increased : Thrombocytopenia , von Willebrand disease, Aspirin
therapy
CLOTTING TIME –
• 6-10 minutes
• Increased : Heparin therapy, Clotting factor deficiency

23. PROTHROMBIN TIME -
• 12-14 seconds
• Increased –Warfarin, Vitamin K deficiency, Liver disease, DIC,
Deficiency of factors I, II, V, VII, X.
PARTIAL THROMBOPLASTIN TIME ( PTT) -
• 25-45 seconds
• Increased – Heparin, Defects in intrinsic clotting mechanism,
Haemophilia A and B, Prolonged use of tourniquet before drawing
blood

24. Interpretation of PT and PTT in patients with bleeding disorders -
PT prolonged , PTT normal • Liver disease, Decreased vitamin K, Decreased or defective Factor VII
PT normal, PTT prolonged • Decreased or defective facor VIII,IX, or XI or anticoagulant present
PT and PTT prolonged • Decreased or defective I, II, V, or X ,von Willebrand disease, Liver disease, DIC
PT and PTT normal • Decreased platelet function ,Thrombocytopenia, Factor XIII deficiency, Mild von Willebrand
disease

25. INTERNATIONAL NORMALIZED RATIO
(INR)
• Ratio of the patients PT to control PT standardized for the potency of
the thromboplastin reagent developed by the World Health
Organization (WHO)
• INR = Patient PT
• Control PT
• Normal value < 1

26. • The guidelines of the American college of chest physician (ACCP)
recommend dental surgery without vitamin K antagonists (VKA)
interruption with use of a pro hemostatic agent.
• The interruption of VKA treatment before dental procedures is not
recommended for interventions that are unlikely to cause bleeding for
low and high bleeding risk procedures if the INR of the patient is < 3.5
24 hours before the planned intervention.
• If the INR > 3.5,the procedure should be delayed until INR values has
been reduced to < 3.5.
Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians
Evidence-Based Clinical Practice Guidelines

27. CALCIUM
• 8.5 to 10.5 mg/dl
• Increased : Hyperparathroidism, Hypervitaminosis D, Metastatic bone
tumors, Pagets disease, Multiple myeloma, Sarcoidosis, Chronic renal
failure.
• Decreased : Hypoparathyroidism, Hypoalbuminemia, Renal failure,
Alkalosis, Acute pancreatitis, Convulsions, Vitamin D deficiency.

28. PHOSPHORUS
• 2.3 to 4.7 mg/dl
• Increased : Hypoparathroidism, Chronic renal failure, Acidosis,
Hypervitaminosis D, Addison s disease.
• Decreased : Hyperparathyroidism,Alcoholism,Hypokalemia, Vitamin D
deficiency, Alkalosis, Diabetes mellitus.

29. GLUCOSE
• Increased : Diabetes mellitus, Stress, Hyperthyroidism, Pregnancy,
Pancreatic disease, Steroid therapy, Cushing syndrome.
• Decreased : Reactive hypoglycemia , Pancreatic disorders, Starvation,
Liver disease, Hyperinsulinism, Hypothyroidism, Hypopituitarism,
Addison disease, Sepsis.

30. FASTING PLASMA GLUCOSE (FPG)
• Fasting blood sugar levels.
• Not having anything to eat or drink for at least 8 hours before the test.

31. RANDOM PLASMA GLUCOSE TEST
• This test is a blood check at any time of the day.
• Diabetes is diagnose at blood sugar of > 200 mg/dl.
Glycated
Haemoglobin(Hb
A1
c
Fasting Plasma Glucose
(FPG)
Oral Glucose Tolerance
Test (OGTT)
Normal <5.7% <100 mg/dl <140mg/dl
Prediabetes 5.7% to 6.4% 100 mg/dl to 125 mg/dl 140 mg/dl to 199 mg/dl
Diabetes 6.5% or higher 126 mg/dl or higher 200 mg/dl or higher

32. GLYCATED HEMOGLOBIN TEST(HbA1c)
• Determine how well you are managing your diabetes.
• Glucose enters your red blood cells and links up (or glycates) with
molecules of hemoglobin.
• HbA1c reflects average plasma glucose over the previous 8 to 12
weeks.

34. Blood Chemistry Tests
• Electrolytes
• Anion gap
• Renal function
• Liver function

35. Electrolytes
SODIUM – 135to 145 mEq/L
• Increased- Dehydration, Glycosuria,Diabetes insipidus
• Decreased- Diuretics, CHF,Hyperglycemia,Renal failure,
Vomiting,Diarrhoea

36. CHLORIDE -
• 95 to 108 mEq/L
• Increased –Dehydration,Non anion gap metabolic acidosis,Diarrhoea,
Diabetes insipidus
• Decreased – Vomiting, Excess sweating,CHF,CRF, Diuretics, DM with
ketoacidosis

37. POTASSIUM
• 3.5-5.2 mEq/L
• Increased –Renal failure,Adrenal insufficiency, Acidosis,Hemolysis
• Decreased- Diuretics, Alkalosis, Vomiting,Nasogastric suctioning.

38. BICARBONATES
• 24 to 30 mEq/L
• Increased-Dehydration, Respiratory acidosis, Emphysema,Vomiting
• Decreased- Metabolic acidosis,Respiratory alkalosis,Renal failure,
Diarrhoea

39. Anion Gap
• 8 to 12mEq
• Difference in mEq between serum sodium and sum of serum chloride
and bicarbonate
• Normal – Diarrhoea, Renal tubular acidosis
• Increased – Renal failure, Lactic acidosis, Ketoacidosis, Salicylate
toxicity.
• Decreased- DIC, Multiple myeloma

40. Renal Function
Blood urea nitrogen (BUN) :-The end product of protein metabolism is urea, which is
excreted entirely by the kidneys; therefore, the BUN is an indication of liver and kidney function
• 6 to 20 mg/dL
• Increased – Renal failure, Dehydration, GIT bleeding, Increesed
protein catabolism.
• Decreased – Liver damage, Protein deficiency, Starvation.

41. Creatinine
Creatinine is formed when creatinine phosphate is used in skeletal muscle
contractions, which is entirely excreted by the kidneys; therefore, the serum
creatinine levels are an indication for renal function. The creatinine level is not
affected by hepatic function so it is a more precise indication of renal function
than is the BUN. A 50% reduction in glomerular filtration rate (GFR) doubles
the creatinine level.
• 0.7 to 1.4 mg/dl
• Increased – Renal failure, Muscle disease
• Decreased – Pregnancy

42. Urine Analysis
Cloudy, foul smelling, WBCs—urinary tract infection (UTI)
Dark yellow—dehydration
Acetone odour—diabetic ketoacidosis
Presence of protein—injured glomerular membrane
Glucose—diabetes mellitus
Ketones—fatty acid metabolism
Crystals—renal stone formation possible
Many hyaline casts—proteinuria
Cellular casts—nephrotic syndrome

43. Liver function
• Bilirubin
• Alkaline phosphatase (ALP)
• Gamma glutamyl transferase (GGT)
• Alanine aminotransferase/serum glutamic pyruvic transaminase (ALT/SGPT)
• Aspartate aminotransferase/serum glutamic oxaloacetic transaminase (AST/SGOT)
• Albumin
• Prothrombin time
• Lactate dehydrogenase (LDH)

44. Indication Examples
History or examination findings suggest liver
disease
• History of poisoning(e.g. Paracetamol)
• Jaundice on examination
• History of alcohol abuse
• Signs of chronic liver disease including
ascites
• Family history of haemochromatosis
Screening for population at high risk of
blood borne virus infection
• Contact tracing in cases of hepatitis
• Indigenous patients
• Illicit drug use
• Previous transfusion
Significant nonliver disease that may effect
liver function
• Malignancies
• Hypoxia
Monitoring medications • Valproate
• Methotrexate
Indications for Liver Function Tests

45. Serum Billirubin
• 0.2 -1.0 mg/dl
• Conjugated bilirubin - 0.2 -0.4 mg/dl
• Unconjugated bilirubin – 0.2 – 0.6 mg/dl
• Estimated by van den Bergh reaction

46. Alanine transaminase (ALT)
Female: 7– 30 U/L
Male: 10–55 U/L
Aspartate transaminase (AST)
Female: 7– 30 U/L
Male: 10– 55 U/L
Increased in: Hepatitis, cirrhosis, liver cancer, biliary
obstruction (cholestasis), bone metastasis, congestive
heart failure, muscle inflammation, infectious
mononucleosis, shock, trauma.
Drugs that increase: ACE inhibitors, acetaminophen,
anticonvulsants, antibiotics, heparin, NSAIDs
Increased in: Acute hepatocyte injury due to drugs (e.g.
acetaminophen overdose), viruses (e.g. hepatitis A,
hepatitis B), or ischaemia (e.g. myocardial infarction,
Hepatitis, pancreatitis, liver CA.
Decreased in: Beriberi, diabetic ketoacidosis,
haemolysis, pregnancy, uraemia
Drugs that increase: Acetaminophen, allopurinol,
antibiotics, chlorpropamide, cholinergics, methyldopa,
vitamin A
Drugs that decrease: Metronidazole

47. Alkaline Phosphatase (ALP)
Female: 30–100 U/L
Male: 45– 115 U/L
Increased in: Biliary obstruction, bone metastasis, calcium deficiency, CA pancreas, cirrhosis, eclampsia,
fracture, hepatitis, high fat intake, hyperparathyroidism, infectious mononucleosis, leukaemia, CA liver,
osteogenic sarcoma, osteomalacia, Paget's disease, pancreatitis, pregnancy, RA, rickets, vitamin D deficiency.
Decreased in: Cystic fibrosis, excessive vitamin D intake, hypophosphataemia, perinicious anaemia, celiac
disease, chronic nephritis, scurvy.
Drugs that increase: ACE inhibitors, anticonvulsants, heparin, NSAIDs, oestrogens.
Drugs that decrease: Fluorides, propranolol

48. Gamma Glutamyl Transferase (GGT)
Female: 5– 29 U/L
Male: 5–38 U/L
Increased in: Acute pancreatitis, alcoholism, biliary obstruction, cholecystitis, cholelithiasis,
cirrhosis, hepatitis, MI, renal cancer, SLE GGT is a sensitive marker of alcohol ingestion and
certain hepatotoxic (liver toxic) drugs Marker of cholestasis, but may be due to alcohol and
other drugs through enzyme induction
Drugs that increase: Aminoglycosides, barbiturates, NSAIDs, phenobarbital, phenytoin.
Drugs that decrease: Oral contraceptives.

49. Total protein- 6.0 to 8.5 g/dl
• Increased –Multiple myeloma, Dehydration, Sarcoidosis
• Decreased – Liver failure, Starvation, Inflammatory bowel disease
Albumin – 3.5- 5.0 g/dl
• Increased – Dehydration
• Decreased- Liver failure, Starvation, Hyperthyroidism, Leukemia,
Nephrotic syndrome

50. Microbiology
• 1.HIV
• 2.HbsAg
• 3.VDRL

51. 1.HIV
• Enzyme-linked immunosorbent assay(ELISA) (Screening test)
• Western blot -Used for confirming presence of HIV antibody
• Positive – AIDS.

52. 2.HbsAg
• Hepatitis B virus (HBV)
• A ‘positive’ or ‘reactive’ HbsAg test result means that the person is
infected with hepatitis B.
• Can spread the hepatitis B virus to others through blood.

53. 3.VDRL
• Venereal disease research laboratory test
• Screening test for syphilis.
• If positive,confirm the results with an FTA-ABS test

54. Special Investigations-
• 1.CRP
• 2.Blood Gases

55. C-reactive protein(CRP)
• Acute phase protein
• Normal value-Less than 10 mg/l
• Sensitive systemic marker of inflammation and tissue damage.
• During infectious or inflammatory disease states, CRP level rise
rapidly within the first 6 to 8 hours and peak at levels of up to 350-
400 mg/L after 48 hours.
• CRP, binds to pathogens and activates the complement to enhance
opsonisation and clearance, even before the production of specific
IgM or IgG.

56. Higher level seen in-
• Late pregnant women
• Mild inflammation and viral infections(10-40 mg/L)
• Acute inflammation
• Bacterial infection(40-200 mg/L)
• Burns(>200mg/L)

57. Blood Gases -
Indications for measurement-
• Altered ventilatory status : Stroke,Asthma,COPD
• Hypoxemia : Pneumonia
• Hypocapnia : Hyperventilation
• Hypercapnia : COPD
• pH disturbance : Ketoacidosis

58. Normal Values – Arterial Blood Sample
• pO2- 80-95 mmHg
• SaO2 – 93% to 98%
• pCO2- 36 to 43 mmHg
• HCO3 – 20-30 mEq/L
• Arterial pH -7.35-7.45

59. Interpretation of Arterial Blood Gas Results -
• Arterial pH
• <7.35 =Acidosis
• 7.35 to 7.45 = Normal,Compensated or mixed disorder
• >7.45 = Alkalosis

61. Routine preoperative tests for elective surgery –NICE guidelines 2016

66. Conclusion-
• Preoperative laboratory tests should be ordered bases on defined
indications such as positive findings on a history and physical exam.
• A thorough history and physical examination can be used to identify
those medical conditions thar might affect perioperative
management and direct further laboratory testing.

67. References-
• Textbook of Biochemistry,Dr. U Satyanarayana
• Textbook of Physiology,6th edition,AK jain
• Clinicians handbook of Oral & maxillofacial surgery, Daaniel M.Laskin
• Routine preoperative tests for elective surgery –NICE guidelines 2016