BIOCHEMICAL INVESTIGATIONS.pptx

biochemical investigation

1. ROUTINE BIOCHEMICAL INVESTIG A TIONS Dr Ganesh BR

2. Need for Laboratory Investigation : Evidence shows Case History and Clinical examination usually reveal most if not all of clinically relevant data . Hence there remains a need to confirm our clinical impression . Lab investigations supplement rather than replace other methods for gathering information . It is a known fact that with the help of lab investigations, some underlying systemic conditions of which the patients are unaware of, are often identified in medical practice for the first time .

3. Definition: Laboratory studies are an extension of physical examination in which tissue, blood, urine or other specimens are obtained from patients and subjected to microscopic, biochemical, microbiological or immunological examination. Information obtained from these investigations help us in identifying the nature of the disease.

4. Biochemi cal Investigation : Also called chemical pathology . Deals with investigations of the metabolic abnormalities of the body in disease states. Investigations are carried out by assays of various normal and abnormal compounds found in body fluids viz. blood, urine, CSF, saliva etc.

5. Classifications: CBC - Hb, Hct, Absolute and differential WBC Bleeding studies – CT, PT Peripheral Blood Smear Random Blood Glucose Tests for disturbance of bone – Ca, P , ALP ESR Urinalysis Screening Test for Syphilis Enzyme testing – CPK, SGOT, SGPT, LDH Bilirubin Estimation Creatinine Estimation Acid Phosphatase FREQUENTLY USED OCCATIONALLY DONE RARELY ORDERED

6. Haematological Investigations (Frequently used) : Complete Blood count includes: Hb PCV RBC Count Platelet count ESR RBC Indices

7. Haematological Investigations:  RBC Count: Normal range – Adult male : 4-6 million cells/cu. mm - Adult female : 3-5 million cells/cu. mm Polycythaemia Anaemia Abnormally high values of circulating RBCs; may be primary or secondary Abnormally low values of circulating RBCs Seen in abnormality of bone marrow (primary) or altitude related (secondary) May result from chronic haemorrhage, bone marrow failure (secondary to radiation, drugs or tumor associated)

8. Haematological Investigations: Haematocrit (Hct) : Volume of packed erythrocytes/100ml of blood done in a centrifuge Although test is inaccurate, it is more precise than the erythrocyte count and is used in combination with it Normal range: Adult male : 40-54% Adult female : 38-47% In general these values are increased in polycythaemia and reduced in anaemia.

9. Haematological Investigations: Haemoglobin(Hb) : Oxygen carrying component of erythrocytes Hence, amount of Hb in the RBCs indicates the level at which it can supply oxygen to the tissues Normal range – Adult male : 14 -18 g% Adult female : 12 – 16 g% Low values indicate anaemia while high values indicate polycythaemia

10. Haematological Investigations: Peripheral Smear: Provides info concerning the size and shape of the red blood cells It may allow Identification of sickle cell & normocytic, microcytic and macrocytic anaemia Evaluation of Hb pigmentation of individual cells to be classified as normochromic, hypochromic or hyper chromic

11. Haematological Investigations: Mean Cell Volume(MCV): Ratio of Haematocrit to RBC count expressed in µm 3 . Describes volume of RBC range: Normal – 82-92/ µm 3 Normocytic anaemia – 82-92/ µm 3 Microcytic anaemia – 50-80/ µm 3 Macrocytic anaemia – 95-100/ µm 3

12. Haematological Investigations: Mean Cell Haemoglobin(MCH): Ratio of Hb to RBCs and is expressed in picograms It expresses the Hb component of each cell range: Normal – 27-31 pcg Normocytic anaemia – 25-30 pcg Microcytic anaemia - 15-25 pcg Macrocytic anaemia - 30-50 pcg

13. Haematological Investigations: Mean Cell Haemoglobin Concentration(MCHC): Ratio of Hb to Hct Value expressed as a percentage of volume of red blood cells. Measures Hb concentration in grams/100ml of packed erythrocytes range: Normal – 32-36% Normocytic anaemia – 32-36% Microcytic anaemia - 25-30% Macrocytic anaemia - 32-36%

14. Haematological Investigations: Erythrocyte Sedimentation Rate (ESR or Sed Rate): In certain febrile diseases as well as in others the amount of circulating fibrinogen is increased The resultant increased viscosity of blood slows down the sedimentation rate of erythrocytes ESR indicates the speed with which the erythrocytes settle in uncoagulated blood Values: Men ( < 50 years ) - <15 mm/hr. Women ( < 50 years ) - <20 mm/hr. Men ( >50 years ) - <20 mm/hr. Women ( >50 years ) - <30 mm/hr.

15. Haematological Investigations: Erythrocyte Sedimentation Rate (ESR or Sed Rate): Interpretation: Raised ESR Lowered ESR Tuberculosis Polycythaemia SABE Spherocytosis Acute MI Sickle Cell Anaemia Septic Shock Congestive Heart Failure Anaemia New Born Infant

16. Haematological Investigations: White Blood Cell Count: (WBC) The white blood cells or Leukocytes are classified as either granulocytes or agranulocytes Normal range: 4500-11000 cells/mm 3 High values may be caused by leukaemia, polycythaemia or infectious diseases Low values may be due to bone marrow depression, aplastic anaemia, drug reactions and viral infections viz influenza

17. Haematological Investigations: Differential White Blood Cell Count: (DLC) Obtained from a peripheral blood smear The granular and nongranular leukocytes are counted and its values are expressed as a percentage of Total WBC Neutrophils: Band neutrophils are immature while seg neutrophils are mature Normal Band value – 2-3% while normal seg value – 50-60% High Band value may indicate presence of an acute infection while Low value may indicate bone marrow depression High Seg values may indicate AML, drug/poison intoxication while Low value may indicate malignant neutropenia or aplastic anaemia

18. Haematological Investigations: Differential White Blood Cell Count: (DLC) Basophils: Normal value : 0 – 1% High values uncommon; may indicate myeloproliferative disease Low values may indicate an oncoming anaphylactic reaction Eosinophils: Normal value : 0 – 5% High values are mostly observed in allergies or parasitic infections Low values are mostly observed in aplastic anaemia and patients on cortisone therapy

19. Haematological Investigations: Differential White Blood Cell Count: (DLC) Lymphocytes: Normal value : 30 – 40% High values may indicate chronic/viral infections, lymphocytic leukaemia Low values may indicate aplastic anaemia or myelogenous leukaemia Monocytes: Normal value : 3 – 7% High values are seen in Monocytic leukaemia Low values are mostly seen in aplastic anaemia

20. Haematological Investigations: Bleeding Time: Measures the time for haemostatic plug formation Normal Bleeding time : 2-7 mins Any clotting factor deficiency or platelet abnormality will lead to increased BT Prolonged in Thrombocytopenia Acute leukaemia Aplastic anaemia Liver diseases

21. Haematological Investigations: Clotting Time: Measures the time required for formation of first clot. Screening test for coagulation disorders Normal Clotting time : 4-14 mins

22. Haematological Investigations (infrequently required) : 1. Prothrombin Time (PT): Time in seconds that is required that is required for fibrin threads to form in citrated (OR) oxalated plasma Normal time : 11-14 secs Measured against a Control PT in terms of INR INR = PT Test / PT Normal Normal INR = 1 ; Abnormal INR > 1.5 Measures extrinsic and common pathway – Factors I, II, V, VII, X

23. Haematological Investigations (infrequently required) : 1. Prothrombin Time (PT): Increased PT Disseminated Intravascular Coagulation Patients on Warfarin Therapy Vit K deficiency Early & End stage Liver failure

24. Haematological Investigations (infrequently required) : 2. Activated Partial Thromboplastin Time ( aPTT ): Time in seconds that’s required for a clot to form in citrated or oxalated plasma Performance indicator of both the intrinsic & common pathways Typical reference range : 30-40 secs Increased aPTT seen in : Patients on Heparin Therapy Disseminated Intravascular Coagulation Early Stage Liver failure Haemophilia

25. Serum chemistry (frequently used): 1. Blood Glucose estimations: Fasting Blood Sugar(FBS): Normal values : 70-90 mg/100ml Random Blood Sugar(RBS): 110-130 mg/100ml Post Prandial Blood Sugar(PPBS): <140 mg/100ml High values are seen in Diabetes mellitus, Cushing’s disease, pheochromocytoma, in patients taking corticosteroids Low values seen in insulin secreting tumours, Addison’s, Pituitary hypo function

26. Serum chemistry(frequently used): 3. Glycated Haemoglobin (HbA 1c ): Hb becomes Glycated by ketoamine reactions between glucose and other sugars. Once Hb is Glycated, it remains that way for a prolonged period (2-3 months) Hence it provides a definitive value of blood sugar control of 2-3 month duration The HbA 1c fraction is abnormally elevated in diabetic patients with chronic hyperglycaemia It is considered to be a better indicator for diabetic control compared to blood glucose levels

27. Serum chemistry (frequently used):

28. Serum chemistry (infrequently used): 1. Serum Calcium, Phosphorus: Indicated on suspicion of Paget’s disease, fibrous dysplasia, primary and secondary hyperparathyroidism, osteoporosis, multiple myeloma or osteosarcoma The conc entration o f Serum Ca varies inversely with serum P Normal level Serum Ca : 9.2-11 mg/dl Normal level Serum P : 3- 4.5 mg/dl At levels less than 7 mg/dl Serum Ca, signs of tetany may appear

29. Serum chemistry(infrequently used): Serum Uric Acid: End product of purine metabolism Normal values: Males : 2.1-7.8 mg/100ml Females : 2.0-6.4 mg/100ml Abnormally high uric acid level seen in Gout, Renal failure, leukaemia, lymphoma, starvation , lead poisoning & cancer chemotherapy & Low values are rare

30. Serum chemistry(infrequently used): Serum Creatinine: Metabolic product of dephosphorylation of creatinine phosphate Raised in late stage Renal disease Its analysis is preferred to Serum Urea analysis as dietary protein intake and protein catabolism do not alter its levels in the body Levels > 15 mg/dL indicates impaired renal metabolism

31. Serum chemistry (infrequently used): Serum Bilirubin: (Brb) Bilirubin is a bile pigment derived from the breakdown of Haemoglobin Normal value: 0.1 – 1.2 mg/100ml Levels beyond 3.0 mg/100ml may indicate jaundice High values may also indicate haemolytic anaemia, biliary obstruction, hepatitis

32. Serum chemistry (infrequently used): LDH, SGOT, SGPT: LDH is responsible for the oxidation of lactic acid to pyruvic acid Normal range: 71-207 IU/L SGOT(AST) is responsible for conversion of amino acids to keto acids Normal range: 0-35 IU/L SGPT(ALT) is responsible for diagnosis of liver functions more so than SGOT levels Normal range: 0-35 IU/L These enzymes can be indicative of liver disease. However, these enzymes are also found in other body tissues such as bone, heart, kidney, etc. Isoenzyme tests usually must be performed in order to isolate the isoenzyme that is elevated and if the source is the liver.

33. Serum chemistry (infrequently used): Blood Electrolytes: An automated analysis usually includes Sodium (Na), Potassium (K), C hloride (Cl) and Bicarbonates (HCO 3 ) Normal values: Sodium 136-145 mEq/L Potassium 3.8-5.5 mEq/L Chloride 95-105 mEq/L Bicarbonates 22-28 mEq/L

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