Liver & RENAL FUNCTION TESTS

1. Liver & RENAL FUNCTION TESTS Lecture by: Dr. Nivedita L. Rao

2. Liver function tests Kidney function tests Organ function tests Organ function tests They are groups of clinical lab tests used to evaluate functions of specific organs.

3. LIVER FUNCTION TESTS (LFTs): Introduction : • Liver has critical biochemical functions in- -Metabolism -Digestion -Detoxification -Excretion of substances from body • These functions are often deranged in liver diseases

4. Definition of LFTs Liver function tests (LFTs) are groups of biochemical tests done to evaluate the functional state of the liver.

5. Group I Tests based on hepatic detoxification and excretion functions Tests based on hepatic synthetic function Classification of LFTs: Group II Group III Measurement of serum enzymes

6. 1 2 Serum Bilirubin LFTs Group I: Based on hepatic detoxification and excretion functions Urine - Bilirubin, Bile salts, Urobilinogen

7. 1 Estimation of Serum Bilirubin LFTs Group I : • van den Bergh reaction is used for the colorimetric estimation of bilirubin • serum total, unconjugated and conjugated bilirubin can be estimated using the method

8. Principle of van den Bergh reaction: Conjugated bilirubin Diazotized sulphanilic (water soluble) acid “Direct bilirubin” Azobilirubin(purple colored complex)

9. van den Bergh reaction: Unconjugatedbilirubin Diazotized sulphanilic (water insoluble) acid “Indirect bilirubin” Methanol Azobilirubin(purple color)

10. van den Bergh reaction: Total Bilirubin Diazotized sulphanilic acid (Conjugated & Unconjugated) Methanol Azo bilirubin (purple colored complex)

11. van den Bergh reaction: Total bilirubin Direct bilirubin Indirect bilirubin (Conjugated) (Unconjugated) • When both conjugated and unconjugated bilirubin levels are ↑ in serum, a purple color is got on direct reaction, which intensifies on addition of methanol. • This reaction is “Biphasic”

12. Normal serum bilirubin levels:

13. Interpretation/ Clinical significance of serum bilirubin values:

14. 2 LFTs Group I : Urine Tests

15. Serum Albumin 1 2 3 Prothrombin time Serum Total proteins LFTs Group II: Tests based on hepatic synthetic function

16. 1 and 2 Serum Total proteins and Albumin LFTs Group II :

17. 3 Prothrombin time (PT) LFTs Group II : • Prothrombin (coagulation factor II) and many other coagulation factors are synthesized in liver and that can be assessed by PT test. • PT is prolonged or increased in, -chronic liver disease (eg. cirrhosis of liver) -obstructive jaundice

18. Gamma glutamyl transferase (GGT) 1 4 3 Alanine transaminase (ALT) 2 Alkaline phosphatase (ALP) Aspartate transaminase (AST) LFTs Group III Measurement of serum enzymes

19. A) Enzyme markers of hepatocellular damage • ALT is more specific for liver • Ratio of AST to ALT is also used to assess liver damage

20. B) Enzyme markers of biliary obstruction/ cholestasis

21. Detecting the presence of liver disease Gauging the extent of known liver damage 1 2 4 3 5 Monitoring individuals exposed to hepatotoxic drugs Distinguishing different types of liver disorders LFTs are used for: Following the response to treatment

22. Answer this… Detoxification and excretion function of liver can be assessed by estimation of serum- a) Albumin b) Globulins c) Bilirubin d) Alkaline phosphatase

23. You have successfully completed learning the topic: Liver Function Tests

24. RENAL (Kidney) FUNCTION TESTS(RFTs)

25. Functions of kidneys: Excretory function: elimination of wastes Maintenance of pH, water and electrolyte balance Endocrine function: production of erythropoietin, calcitriol (active form of Vitamin D) and prostaglandins Note: These functions are often deranged in renal disease

26. Definition: • Renal function tests are groups of biochemical tests done to evaluate the functional state of the kidneys.

27. I. Tests to assess Glomerular function II. Tests to assess Tubular function Classification of RFTs A. Clearance tests B. General tests 1. Creatinine clearance 2. Urea clearance 1. Blood tests - Creatinine, Urea 2. Urine analysis • Concentration and dilution studies

28. Definition of clearance: It is the volume of plasma that contains the amount of substance excreted (cleared) by the kidneys in oneminute. Clearance of a substance from plasma depends on GFR.

29. Formula to calculate clearance: Clearance = mg. of substance excreted in urine per min (u) (ml /min) mg. of substance per ml plasma (p) = u v p •  u = concentration of the substance in urine • p = concentration of the substance in plasma or serum • v = the volume (in ml) of urine excreted per minute

30. Marker substances used in clearance tests: • Endogenous:Creatinine, Urea, Cystatin C (new) • Exogenous: Inulin

31. An ideal clearance marker, • should be an endogenous substance • should be freely filtered across the glomerulus • should not be reabsorbed or secreted by the renal tubules Clearance of such an ideal substance = GFR Note: None of the endogenous markers listed, fulfill all these criteria

32. 1. Creatinine clearance test: It is a RFT used to assess glomerular function of kidneys. • Creatinine is an endogenous substance (from muscle creatine). • Its level in blood is not dependent on diet, age or exercise. (It is however, dependant on the muscle mass of the body) • Its blood levels do not fluctuate much. • Its excretion is constant. • It is not secreted and is minimally reabsorbed by the tubules.

33. Creatinine clearance (ml /min): = mg. of creatinine excreted in urine per min (u) mg. of creatinine per ml plasma (p) = u v p Normal creatinine clearance value is 90 to 120 ml/ min Interpretation: Decrease in creatinine clearance value is a sensitive indicator of decreased glomerular function.

34. 2. Urea clearance test • It is a RFT used to assess glomerular function of kidneys. • Urea is the end product of protein (amino acid) metabolism. • Urea is freely filtered but partially reabsorbed by the tubules. • Therefore, normal urea clearance valueswill be lessthan theactual GFR. • Plasma urea concentration is influenced by dietary protein intake.

35. Urea clearance (ml /min): = mg. of urea excreted in urine per min (u) mg. of urea per ml plasma (p) = u v P Normal urea clearance value is about 75 ml/min. Decreased urea clearance value indicates decreased glomerular function.

36. General Tests for glomerular function Blood tests: Normal levels Plasma creatinine: 0.7 – 1.5 mg /dl (values are lower in females) Blood urea: 15 - 40 mg / dl Interpretation: plasma creatinine and blood urealevels indicate glomerular function But, blood urea level is also influenced by changes in dietary protein intake.

37. Urine tests:

38. RFTs are used for: • Diagnosing renal disease • Assessing extent of renal damage • Monitoring response to treatment for renal disease • Monitoring renal function during treatment using nephrotoxic drugs

39. Learning checks: Answer this MCQ…. The most common clearance marker which is used for assessment of glomerular function is, a) Inulin b) Urea c) Uric acid d) Creatinine

40. Writing tasks • Make a table with the names of liver function tests and write the significance of each test. • Write a short note on Creatinine clearance test.

41. You have successfully completed learning the topic: Renal Function Tests