Lab diagnostics are now becoming a importantand mandatory technique to bring out theadditional information about a patient. It makes the clinicians must have anunderstanding and working knowledge ofdiagnostic modalities other than their own areaof expertise. Laboratory diagnostic are usually used inconjunction with thorough history and physicalexamination to know valuable information aboutthe patient status and response to therapy thatmay not be apparent from the history andphysical examination.
Generally a diagnostic test is used to1. Basic screening2. Establishing diagnosis3. Differential diagnosis4. Evaluating current medicalcondition5. Evaluating disease severity6. Monitoring response of treatment7. Regularly scheduled screening testas a part of ongoing care
FACT- Nearly 45 million people surf internetabout medical conditions and diagnostics. Itbecomes the responsibility of an physician toexplain them about how it differs fromactual situation.
Explanation of test Indications for testing Signs,symptoms and history of disease Normal reference values Informed consent
Actual description of procedures Specimen collection and transport Provide comfort to patient Interfering factors
Interpret test results Provide social support and counsel forunexpected outcomes Order follow up tests at appropriate interval Reeducate patient for future testing Document and maintain proper records
Ensure the specimens are correctly obtained,preserved,handled,labeled and delivered tolab. Follow universal precautions and infectioncontrol policies. Health care personnel should protectthemselves with appropriate use ofprotective measures.
Incorrect specimen collection,handling andstorage Wrong or lack of preservative Hemolysed blood samples Incorrect pretest diet Incorrect labeling
Give information that relates to what thepatient will physically feel and theequipment that will be used Encourage questions and verbalization offeelings,fears and concerns. Inform the patient that the test results willcome only after certain period of time. Provide emotional support for the patient.
Pregnancy testRandom blood sugar testHemoglobin testMalaria testUrine dip test
White blood cell (WBC, leukocyte) count:-White blood cells protect the body againstinfection. If an infection develops, whiteblood cells attack and destroy thebacteria, virus, or other organism causing it.When a person has a bacterial infection, thenumber of white cells rises very quickly. Thenumber of white blood cells is used to findan infection .
The major types of white blood cellsare neutrophils, lymphocytes, monocytes, eosinophils, and basophils. Immatureneutrophils, called band neutrophils, are alsopart of this test. Each type of cell plays adifferent role in protecting the body. Thenumbers of each one of these types of whiteblood cells give important information aboutthe immune system. Too many or too few ofthe different types of white blood cells canhelp find an infection, an allergic or toxicreaction to medicines or chemicals, andmany conditions, such as leukemia.White blood cell count:-(WBC differential)
Red blood cell (RBC) count. Red blood cells carry oxygen fromthe lungs to the rest of the body. They alsocarry carbon dioxide back to the lungs so itcan be exhaled. If the RBC count is low(anemia), the body may not be getting theoxygen it needs. If the count is too highthere is a chance that the red blood cells willclump together and block tiny blood vessels(capillaries). This also makes it hard for yourred blood cells to carry oxygen.
Hemoglobin (Hgb).The hemoglobin molecule fills up thered blood cells. It carries oxygen andgives the blood cell its red color. Thehemoglobin test measures the amountof hemoglobin in blood and is a goodmeasure of the bloods ability to carryoxygen throughout the body
Hematocrit This test measures the amount of space(volume) red blood cells take up in theblood. The value is given as a percentage ofred blood cells in a volume of blood. Forexample, a hematocrit of 38 means that 38%of the bloods volume is made of red bloodcells. Hematocrit and hemoglobin values arethe two major tests that show if anemia ispresent.
Red blood cell indices.There are three red blood cell indices: meancorpuscular volume (MCV), mean corpuscularhemoglobin (MCH), and mean corpuscularhemoglobin concentration (MCHC).The MCVshows the size of the red blood cells. The MCHvalue is the amount of hemoglobin in an averagered blood cell. The MCHC measures theconcentration of hemoglobin in an average redblood cell. These numbers help in the diagnosisof different types of anemia.
Red cell distribution widthRed cell distribution width (RDW) canalso be measured which shows if thecells are all the same or different sizesor shapes.
Platelet count (Thrombocyte)Platelets (Thrombocytes) are the smallesttype of blood cell. They are important inblood clotting. When bleeding occurs, theplatelets swell, clump together, and form asticky plug that helps stop the bleeding. Ifthere are too few platelets, uncontrolledbleeding may be a problem. If there are toomany platelets, there is a chance of a bloodclot forming in a blood vessel. Also, plateletsmay be involved in hardening of the arteries
Keep Taking the MedicinePatient: Its been one month since my lastvisit and I still feel miserable.Doctor: Did you follow the instructions onthe medicine I gave you?Patient: I sure did - the bottle said keeptightly closed.
Normal values-4.5-10.5 *10³cells/mm³or 4500-10500 cells/mm3 Leucocytosis->11,000mm31. Acute severe infections2. Leukemias3. Tissue injury4. Steroid therapy Leukopenia <4000mm31. Viral infections2. Drugs like antibiotics,analgesics3. Aleukemia4. Aplastic anemia
The WBC ‘s are classified majorly into 2categories1.Granulocytes(with nucleus) Neutrophil Basophil Eosinophil2.Agranulocytes(without nucleus) Lymphocytes Monocytes
It increases in pyogenic(bacterial) infections Normal value -3000-7000mm3 Neutrophilia >8000/mm31.Bacterial infection2.Inflammation3.chemicals and toxins like venoms4.carcinomas Neutropenia <1800/mm31.Viral infections2.Aplastic anemia
Increases in allergic and parasitic infections Normal 0-3% Eosinophilia>5% or 500 cells/mm31.Allergies2.Asthma3.Parasitic disesase4.Poisons Eosiopenia<50/mm31.certain drugs like thyroxine
Used to study chronic inflammation Normal-0-1% of total WBC Basophilia >50/mm31. Leukemia,2. Less commonly inInflammation,Allergy,Sinusitis Basopenia <20mm31. Infection,2. Hyperthyroid,3. Stress.
It removes injured and dead cells,microorganisms and insoluble particles fromcirculating blood. Normal 3-7% of total WBC Monocytosis->500cells/mm31. Leukemia,2. Carcinoma Stomach,Breast. Decreased monocyte count <100cells/mm31. HIV
Play a main role in immunologic reactions. Normal 25-40% Lymphocytosis>4000/mm31. Leukemia,2. Viral diseases3. Tuberculosis Lymphopenia <1000/mm31. Aplastic anemia2. HIV
The main function of the red blood cell is tocarry oxygen from lungs to body tissues and totransfer carbon di oxide from the tissues tolungs.Normal Men -4.2-5.4*106//mm3 Women- 3.6-5* 106/mm3 Decreased RBC’s Occurs in1. Anemia2. Increased RBC’S3. Primary causes like polycythemia vera4. Secondary cause like renal disease,highaltitude
The test indirectly measures the RBC mass.Normal- Men 42-52% Women 36-48% Decreased HCT<30 % in Anemia,Leukemia Increased HCT in shock.
Hb is the main component of erythrocytesserves as vehicle for transportation of oxygenand carbon di oxide. Women 12-16gms/dl Men 14-17 gms/dl Decreased hemoglobin in Irondeficiency,Liver disease,Pregnancy. Increased hemoglobin in COPD,Congestiveheart disease.
The red blood cell indices define the size andHb content of RBC and consist Mean corpuscular volume(MCV), Mean corpuscular hemoglobinconcentration(MCHC)and Mean corpuscular hemoglobin(MCH).
This index expresses the volume occupied bysingle erythrocyte and measured in cubicmicro meter or femtolitre.The MCV indicateswhether the red blood cell size appearsnormal or smaller. Normal 82-98mm3or 82-98fL Used to find the type of anemia.
This gives the information about the averageconcentration of Hb in RBC’s. Used in monitoring the anemia therapy. Normal 32-36 g/Dl
The MCH is a measure of average weight ofHb per RBC. It is used in knowing the severe anemicpatients.
This indicates the size variation of RBC.Thismeasurement is useful in monitoringresponse to therapy. Normal value-11.5-14.5 Increased in iron deficiency,pernciousanemia.
Platelet activity is necessary for bloodclotting,vasoconstriction and adhesion andaggregation activity. Normal Adult 140-400*103/mm3 Children 150-450*103/mm3 Abnormally increased in renal failure,irondeficiency anemia,malignancy. Abnormally decreased in anemia,congestiveheart failure,HIV. A decrease in <20*103/mm3 platelets isassociated with spontaneous bleeding,petechiae
The MPV indicates the uniformity of size ofplatelet population. Adult and children-7.4-10.4 fL. MPV increased in massive hemorrhage,
P-LCR tells about the ratio of large platelets. Normal values-14-44% Increased in vasculardisease,hyperlidipiemia.
An indication of variation in platelet sizewhich can be a sign of active plateletrelease. PWD Normal Values: 9 - 13 fL Clinical implications: Increased PWD: Iron Deficiency Anemia Folate and vitamin B12 deficiency anemia Hemorrhage.
Eryhthrocyte sedimentation occurs at higherlevel when inflammatory or necrotic process ispresent. ESR is used to find the monitor in progression ofdisease or treatment outcome. Normal value Men-0-15mm/hr Women—20mm/hr Slightly increased in people over 50 yrs of age. Increased ESR is seen in Infections,Inflammatoryprocesses. Normal or same in iron deficiency anemia .
Blood group AIf you belong to the blood groupA, you have A antigens on thesurface of your red blood cells and Bantibodies in your blood plasma.Blood group BIf you belong to the blood groupB, you have B antigens on thesurface of your red blood cells and Aantibodies in your blood plasma.Blood group ABIf you belong to the blood groupAB, you have both A and B antigenson the surface of your red bloodcells and no A or B antibodies at allin your blood plasma.Blood group 0If you belong to the blood group 0(null), you have neither A or Bantigens on the surface of your redblood cells but you have both A andB antibodies in your blood plasma.
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Lipid measures are diagnostic indicators ofhyper or hypolipidemia. The components are Total cholesterol Triglycerides High density lipids Low density lipids
Cholesterol is a lipid (fat) which is produced bythe liver. Cholesterol is vital for normal bodyfunction. Every cell in our body has cholesterolin its outer layer. What are the functions of cholesterol? It builds and maintains cell membranes (outerlayer), It is essential for determining which moleculescan pass into the cell and which cannot (cellmembrane permeability) It is involved in the production of hormones(androgens ,estrogens,cortisol etc) It is important for the metabolism of fatsoluble vitamins, including vitamins A, D, E, andK It insulates nerve fibers
TOTAL CHOLESTEROL Normal values; Adult Desirable - Less than 200 mg/dL Bordeline high - 200 to 239 mg/dL High - 240 mg/dL and above Children Desirable - Less than 170 mg/dL Bordeline high – 170-200 mg/dL High – 200 mg/dL and above Hyperlidemia occurs in renalfailure,hypothyroidism,alchoholism,obesity Hypolidemia occurs in hyperthyroidism,severeburns,mental retardation.
There are three main types of lipoproteins Cholesterol is carried in the blood bymolecules called lipoproteins. A lipoprotein isany complex or compound containing bothlipid (fat) and protein. The three main typesare: Low Density Lipid High Density Lipid Triglycerides
LDL (low density lipoprotein) - people oftenrefer to it as bad cholesterol. LDL carriescholesterol from the liver to cells. If too much iscarried, too much for the cells to use, there canbe a harmful buildup of LDL. This lipoprotein canincrease the risk of arterial disease if levels risetoo high. Most human blood containsapproximately 70% LDL. Normal values Adults- Desirable-<130mg/dl Borderline high-140-159mg/dl High-160mg/dl Increased in familialhypercholesterolemia,obesity,dibetes mellitus Decreased in hyperthyroidism,chronic anemias.
HDL (high density lipoprotein) - people oftenrefer to it as good cholesterol. Experts say HDLprevents arterial disease. HDL does the oppositeof LDL - HDL takes the cholesterol away from thecells and back to the liver. In the liver it is eitherbroken down or expelled from the body aswaste. Normal values Men 35-65mg/dl Women 35-80mg/dl Increased in long term aerobics or vigorousexercise Decreased in poorly controlled diabetesmellitus,chronis renal disease.
Triglycerides - these are the chemical forms inwhich most fat exists in the body, as well as infood. They are present in blood plasma.Triglycerides, in association withcholesterol, form the plasma lipids (blood fat).Triglycerides in plasma originate either from fatsin our food, or are made in the body from otherenergy sources, such as carbohydrates. Calorieswe consume but are not used immediately by ourtissues are converted into triglycerides andstored in fat cells. When your body needs energyand there is no food as an energysource, triglycerides will be released from fatcells and used as energy - hormones control thisprocess.
Desirable-<150mg/dl Borderline high-150-199mg/dl High 200-499mg/dl Increased in hypothyroidism,renaldisease,poorly controlled diabetes. Decreased inmalnutrition,hyperthyroidism
SGOT or Aspartate transaminase(AST) iswidely distributed in tissues with highestconcentration found in liver,heart,skeletalmuscles and kidney. Diseases involving muchof these tissues results in increase in AST inserum. Normal range Men-14-20 U/L Women 10-36 U/L Increased AST in hepatitis,acutecirrhosis,alcoholic hepatitis. Decreased AST in vitamin B6 deficiency.
SGPT or Alanine aminotransferase(ALT) isfound in many tissues especially high in liverwhich ultimately results rise of ALT in liverdisease. Normal value Men-10-40U/L Women 7-35U/L Increased ALT in viral disease,burns,alcoholiccirrhosis.
Bilirubin is a brownish yellow substance found in bile.It is produced when the liver breaks down old redblood cells. Bilirubin is then removed from the bodythrough the stool (feces) and gives stool its normalbrown color. Indirect (or unconjugated) bilirubin. This form ofbilirubin does not dissolve in water (it is insoluble).Indirect bilirubin travels through the bloodstream tothe liver, where it is changed into a soluble form(direct or conjugated). Direct (or conjugated) bilirubin. Direct bilirubindissolves in water (it is soluble) and is made by theliver from indirect bilirubin. Normal values Total 0.3-1.0 mg/dL Conjugated 0-0.2mg/dl Used to check liver function and watch for signs ofliver disease such as hepatitis or cirrhosis, or theeffects of medicines that can damage the liver.
Fasting blood sugar is taken when the bloodglucose level is tested after 8 hrs of nilcaloric intake. Normal FBS -<65-110mg/dL Increased in diabetes mellitus,acuteemotional or stress,chronic liver disease. Decreased in starvation,liverdamage,hypothyroidism
A postprandial glucose test is a bloodglucose test that determines the amount of atype of sugar, called glucose, in the bloodafter a meal. Glucose comesfrom carbohydrate foods. It is the mainsource of energy used by the body. Normal value-<140 mg/dl Increased in diabetesmellitus,pregnancy,advanced liver disease Decreased in carcinoma,liver damage.
The A1C test is a common blood test used to diagnosetype 1 and type 2 diabetes and then to gauge howwell youre managing your diabetes. The A1C testgoes by many other names, including glycatedhemoglobin, glycosylated hemoglobin, hemoglobinA1C and HbA1c. The A1C test result reflects your average blood sugarlevel for the past two to three months.Specifically, the A1C test measures what percentageof your hemoglobin — a protein in red blood cells thatcarries oxygen — is coated with sugar (glycated). Thehigher your A1C level, the poorer your blood sugarcontrol and the higher your risk of diabetescomplications. Normal 4%-6% -Normal 6-7% -Target range for diabetics >7% -High
The tongue is the strongest muscle in thehuman body. Enamel is hardest substance in the humanbody The only part of the body that has no bloodsupply is the cornea in the eye. It takes inoxygen directly from the air. The Hyoid bone, in your throat ,is the onlybone in your body which not attached toother bone.. There are 60,000 miles (97,000 km) of bloodvessels in each human.
Specific gravity is a measurement of kidneyability to concentrate urine and is a measureof density of dissolved chemicals in urine . Normal 1.005-1.030 Increased in dehydration,diabetes mellitus, Decreased in severe renaldamage,Glomerulonephritis
The pH is an indicator of renal tubules abilityto maintain normal hydrogen ionconcentration in plasma and extracellularfluid. The importance of urinary ph used indetermining existence of acid base disorders Normal 6.0-8 Acidic urine<7 in UTI,metabolicacidosis,diarrhea. Alkaline urine >7 in chronic renalfailure,vomiting.
Presence of free hemoglobin in urine isreferred as hemoglobinuria. Blood in urine isalways a result of trauma or damage tokidney or urinary tract. Normal <10 erythroytes/µL,0.003mg freeHb/dL Hematuria is found in UTI,trauma tokidney,urinary calculi. Hemoglobinuria is found inburns,malaria,disseminated intravascularcoagulation.
The presence of increased amount of proteinin urine can be an important indicator ofrenal disease.It may be the first sign of aserious problem and may appear before anyother clinical symptoms. Normal Negative Adult male 1-14mg/dl Adult female 3-10mg/dl
Glucose is present in glomerular filtrate andis reabsorbed by proximal convolutedtubule.if the blood glucose level exceedsreabsorption capacity of tubules glucose willappear in urine. Normal Random specimen –Negative 24 hour specimen 1-15mg/dl Increased glucose appears in diabetesmellitus,endocrine disorders.
In normal healthy persons ketones areformed in liver and are completelymetabolized so that only negligible amountsappear in urine.increased ketones in theblood lead to electrolyte imbalance ,acidosisand eventually coma.The excess presence ofketones in urine is associated with diabetes. Normal Urine-negative(0.03-0.05 mmol/L) Ketosis is found in diabetes mellitus,dietaryconditions like starvation.
Urine nitrite This test is an indirect method to detectbacteria in urine. Normal –negative Urine leukocyte The presence of leukocytes in urine indicatesa UTI. Normal –negative
Bilurubin is formed as a breakdown productof hemoglobin .It aids in diagnosis ofmonitoring and treatment of hepatitis andliver disease. Normal –negative (0-0.02mg/dl)
Urobilinogen is also a breakdown product ofhemoglobin .it is one of the most sensitivetest to determine impaired liver function. Normal –negative<1mg/dl Increased in malaria,hemolytic anemia.
A blood urea nitrogen (BUN) test measures theamount of nitrogen in blood that comes fromthe waste product urea. Urea is made whenprotein is broken down in your body. Urea ismade in the liver and passed out of body in theurine. A BUN test is done to see how well kidneys areworking. If kidneys are not able to remove ureafrom the blood normally, BUN level rises. Normal Adult 6-20mg/dl Elderly 8-23mg/dl Increased BUN in chronic renal disease,urinarytract obstruction,diabetes mellitus Decreased BUN in liverfailure,malnutrition,nephrotic syndrome.
Creatinine is a breakdown product of creatine, whichis an important part of muscle. Creatinine is removedfrom the body entirely by the kidneys. If kidneyfunction is abnormal, creatinine levels will increasein the blood . Normal Men 0.7 to 1.3 mg/dL Women 0.6 to 1.1 mg/dL Higher than normal levels may be due to: Acute tubular necrosis Dehydration Diabetic nephropathy Lower than normal levels may be due to: Muscular dystrophy Myasthenia gravis
Uric acid is a chemical created when thebody breaks down substances called purines.Purines are found in some foods anddrinks, such as liver.Most uric acid dissolvesin blood and travels to the kidneys, where itpasses out in urine. High levels of uric acid inthe body is called hyperuricemia. Normal Men 3.4-7.0 mg/dl Women 2.4-6.0 mg/dl Elevated uric acid levels in renal disease andrenal failure,alcoholism,liver disease Decreased uric acid levels in malignancies.
Magnesium in the body is concentrated inbone(40-60%)and also in muscle and serum.itis used to evaluate renal function,electrolytestatus. Normal Adult-1.8-2.6 mg/dl Children 1.7-2.1 mg/dl Hypomagnesemia occurs inhypercalcemia,diabetic acidosis,chronicrenal disease. Hypermagnesemia occurs in renalfailure,dehydration,hypothyroidism.
Albumin is a protein manufactured by the liver.It helps balance the amount of blood flowingthrough the arteries and veins and moves thecalcium, progesterone, bilirubin and medicationsthrough a person’s blood. It also stops fluid inthe blood from leaking into the tissues. Albumin is used to evaluate nutritionalstatus,liver disease,renal disease. Normal Adult-3.5-5.2 g/dl Increased in dehydration Decreased in cirrhosis,liverdisease,burns,alcoholism
The WIDAL is the diagnostic test forsalmonella typhi infection causing typhoid. The titre of 1:80 is considered as positive intyphoid endemic countries like India. Widal is not so reliable to typhoid as its titrewill also be raised in viral infections. The results should be correlated with clinicalsyptoms.