Organ function Test.pdf

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1. Organ function tests

3. Renal function tests
1.Tests to asses glomerularfunction
2.Tests to asses tubular function
3.Routine urine analysis
4.Analysis of blood/serum

4. Tests to asses glomerularfunction
•The blood supply to kidneys is relatively
large. About 1200 ml of blood (650 ml plasma)
passes through the kidneys, every minute.
•From this, about 120-125 ml is filtered per
minute by the kidneys and this is referred to
as glomerularfiltration rate (GFR).
•Normal GFR is (120-125 ml/min).
•The glomerularfiltrate formed in an adult is
about 175-180 litresper day, out of which
only 1.5 litresis excreted as urine.

5. •The process of urine formation basically
involves two steps—glomerularfiltration
and tubular reabsorption.

6. •Measurement of the clearance is
predominantly a test of glomerularfiltration
rate (GFR).
•Clearance, is defined as the volume of
plasma that would be completely cleared of
a substance per minute.

7. Clearance formula

8. Tests to asses glomerularfunction
1.Creatinineclearance:
C=UV/P
where U is the urine creatinineconcentration, P is
the plasma creatinineconcentration and V is the
urine flow in ml/min (The 24 hr urine collection is
not necessary for the creatinineclearance test).

9. Creatinineclearance test:
Reference values: 100-125 (M) & 90-115 (F)
Significance: decreased values below 75% -impairment of
renal function and renal damage.
•Dehydration
•Glomerulonephritis
•Shock
•Acute nephroticsyndrome
•Acute and chronic renal failure
Creatininelevel in blood: 0 .8 to 1.4 mg/dL

10. Urea clearance
•Urea clearance is defined as the volume (ml)of
plasma that would be completely cleared
of urea per minute.
•It is calculated by the formula

11. •If the output of urine is more than 2 ml
per minute. This is referred to as maximum
urea clearance and the normal value is
around 75 ml/min.
•Standard urea clearance : when the volume
of urine is less than 2 ml/min. This is
known as standard urea clearance. normal
value is around 54 ml/min.

12. Urea clearance :
•Partially reabsorbed by the renal tubules.
•Clearance is less than GFR.
•Significance : value below 75% of normal is
abnormal.
•The values fall progressively with failing renal
function.

13. Inulinclearance :
Fructose polymer
Value :125ml/min

14. TESTS FOR TUBULAR FUNCTION
SPECIFIC GRAVITY :
The simplest test of tubular function is the measure-
mentof the specific gravity (SG) of urine.
Normal = 1.015-1.025
Decreased : excess water intake,DI,nephritis.
Increased :excess perspiration,DM,nephrosis.

15. CONCENTRATION TEST:
SG measured after 12 hr fast.
SG more than 1.022 –adequate renal function.
•In moderate forms of kidney damage, the
inability to excrete the waste products may be
counterbalanced by large urine output.
Thus, the earliest manifestation of renal
disease may be the difficulty in concentrating
the urine.

16. DILUTION TEST:
•BLADDER EMPTIED AT 7AM
•WATER LOAD 1200 ml in 30 min.
•Urine samples collected for next 4 hours.
•A normal person will excrete almost all the
water load within 4 hours and the specific
gravity of at least one sample should fall to
1.003.
•The test is more sensitive and less harmful
than concentration test.

17. Major functions of liver

18. LIVER FUNCTION TESTS
•TESTS BASED ON EXCRETORY FUNCTION
•TESTS BASED ON SYNTHETIC FUNCTION
•DETOXIFICATION
•DIAGNOSTIC ENZYMES

19. BASED ON EXCRETORY FUNCTION:
Estimation of Bilirubin
•Bilirubinis the end product of haemcatabolism
•It is transported to liver by albumin
•In liver bilirubinis conjugated with glucuronate&
secreted into intestine with bile
Total Serum level =0.2-1.0 mg/dl
Unconjugated= 0.2-0.7 mg/dl
Conjugated = 0.1-0.4 mg/dl

20. •Van den berghreaction-detection of serum
bilirubinand the type of jaundice.
Principle: It is based on the formation of a
purple-colored azobilirubin, when serum
containing bilirubinis allowed to react with
freshly prepared diazoreagent.

21. •Van den Bergh Diazoreagent: It is prepared
by mixing sulfanilicacid & sodium nitrite in
HCl.
•When bilirubinis conjugated, the purple color
is produced immediately on mixing with
the reagent, the response is said to be van
den Bergh direct positive.

22. •When the bilirubinis unconjugated, the color
is obtained only when alcohol is added,
and this response is known as indirect
positive.
•If both conjugated and unconjugated
bilirubinsare present in increased amounts,
a purple color is produced immediately and
the color is intensified on adding alcohol. Then
the reaction is called biphasic.

23. Pattern of van den Bergh reaction in
different types of jaundice
Types of jaundiceCauses Types of bilirubinin
blood
Prehepatic Rhincompatibility, Sickle
cell anemia
Unconjugated↑
(indirect positive)
Hepatic Viral hepatitis—A, B, C
Toxic hepatitis—alcohol
Conjugated ↑
Unconjugated↑
(biphasic reaction)
Posthepatic Gallstones,
Pancreatic tumor
Conjugated ↑
(direct positive)

24. •Urinary bilirubin: conjugated bilirubinis
detected by fouchetstest.
•Urinary urobilinogen: extretedin hemolytic
jaundice. Urobilinogenin urine reacts with
Ehrlich'sreagent toform a red color
•Urine bile salts :Hays test

25. Synthetic function
• The liver synthesizes albumin
•It represents a major synthetic protein and is
marker for ability of liver synthesis.
Albumin : half life 20 days
blood : 3.5-5 g/dl.
Prothrombintime :half life is 6hrs.
PT is prolonged in hepatic disorders.

26. Detoxification
•Ammonia detoxification
•Drug metabolism-cytochromeP450

27. Diagnostic enzymes
•Alkaline phosphatase:obstructive jaundice 40-
125 IU/L
•GGT =10-30 IU/L
•Hepatocellulardamage :ALT 10-35 IU/L
AST 8-20 IU/L

29. GASTRIC FUNCTION TESTS
Pentagastrinstimulation test
•Pentagastrinis a synthetic peptide which
stimulates the gastric secretion in a
manner similar to the natural gastrin.
•The stomach contents are aspirated by Ryle’s
tube in a fasting condition. This is referred to
as residual juice.

31. •The gastric juice elaborated for the next one
hour is collected and pooled which represents
the basal secretion.
•Pentagastrin(5 mg/kg body weight) is now
given to stimulate gastric secretion. The
gastric juice is collected at 15 minute intervals
for one hour. This represents the maximum
secretion.

32. •Basal acid output (BAO) refers to the acid
output (millimol/hour) under the basal
conditions i.e. basal secretion. = 2-4 mmol/hr
•Maximal acid output (MAO) represents the
acid output (millimolper hour) after the
gastric stimulation by pentagastrini.e.
maximum secretion. = 15-50 mmol/hr.

33. Augmented histamine test meal
•Histamine is a powerful stimulant of gastric
secretion. The basal gastric secretion is
collected for one hour.
•Histamine (0.04 mg/kg body weight) is
administered subcutaneously and the gastric
contents are aspirated for the next one
hour (at 15 minute intervals).
•The acid content is measured in all these
samples.

34. Abnormalities of gastric function
•Increased gastric HCI secretion is found in
Zollinger-Ellison syndrome (a tumor of gastrin
secreting cells of the pancreas), chronic
duodenal ulcer, gastric cell hyperplasia,
excessive histamine production etc.
•A decrease in gastric HCI is observed in
gastritis, gastric carcinoma, pernicious anemia
etc.

35. PANCREATIC FUNCTION TESTS
•Pancreatic enzymes in serum : Serum
amylase and lipase measurements are
commonly employed to assess the pancreatic
function. Both these enzyme activities are
elevated in acute pancreatitis, obstruction
in the intestine and/or pancreatic duct.