Kidney function tests used in clinical pathology.ppt

Brief review of pathological tests.

1. Presented By:
Uzma Batool

4. Kidneysaretheorganthatfilterwaste
productsfromtheblood.
Thekidneysservethreeessentialfunction:
1.Theyfunctionasfilter,removingmetabolic
productandtoxinsfromthebloodand
excretingthemthroughtheurine.
2.Theyregulatethebody’sfluidstatus,
electrolytebalanceandacid-basebalance.

5. Renalfunctiontestsareusetodetectthe
presenceofrenaldiseasesandassesstheir
progress.

6. Renalfunctionmaybeassessedbymeasuring
bloodureaandserumcreatinine.Renal
functiondecreaseswithage,whichmustbe
takenintoaccountwheninterpretingtest
values.
Thesetestsprimarilyevaluateglomerular
functionbyassessingtheglomerular
filtrationrate.

7. Inmanyrenaldiseases,ureaandcreatinine
accumulateinthebloodbecausetheyarenot
excretedproperly.
Thesetestsalsoaidindeterminingdrug
dosagefordrugsexcretedthroughthe
kidneys.

9. 1.Creatinine
2.Uric acid
3.Urea
4.Glomerular filtration rate

10. Inthemusclescreatineisconvertedtocreatine
phosphatewhichbecomesthesourceofahigh
energyphosphatebondfortheimmediate
reformationofATP.
Creatinineisthebyproductofmuscleenergy
metabolismandisproduceataconstantrate
accordingtothemusclemassoftheindividual.Itis
thesubstancethatiseasilyexcretedbythekidney.
Bythismethodwecanalsoestimateserum
creatinineandurinecreatinine.

11. A measure of the amount of creatinine
eliminated from the blood by the kidney.
The value is given in unit of millions per
minute, representing the volume of blood
cleared by the kidney per minute.
Calculation:
Ccr=U x V/P
U = Urine creatinine concentration in mg/dl
P = Serum creatinine in mg/dl
V = Volume of urine in ml/dl.

12. URINE CREATININE
men : 14-26mg/kg/24 hours
women: 11-20mg/kg/24 hours
SERUM CREATININE
men : 0.6-1.2 mg/dL
women : 0.4-1.0 mg/dL

13. High creatinine level causes:
Acute and Chronic kidney disease
Ureter obstruction
Dehydration
Glomerulonephritis

14. Uric acid is a naturally occurring waste product
resulting from the breakdown of purine,
crystalline compound found in certain foods.
Under normal condition, uric acid dissolves in
the blood, passes through the kidney and is
eliminated with the urine.
Sometime the body produces too much uric
acid or doesn’t filter out enough of it and that
time uric acid level increase in blood.

15. A uric acid blood test also known as a serum uric
acid measurement, determine how much uric
acid is present in your blood.
The test can help determine how well your body
produces and removes uric acid.

16. Clinical significance:
Uric acid is a metabolism of purines, nucleic
acids and nucleo proteins.
Consequently, abnormal levels may be
indicative of a disorder in the metabolism or in
some genetic diseases.

17. High level of uric acid in your blood can also
indicate of a variety of conditions, including:
-diabetes
-gout(acutearthritis)
-chemotherapy&radiation
-leukemia(bonemarrowdisorders)
-hypoparathyroidism
-kidneydisorders(stones)
-metastasizedcancer

18. -low levels of uric acid in the blood may
inluding:
-wilson’s disease
-fanconi syndrome(cystinosis)
-alcoholism
-liver or kidney disease
-a diet low in purines

19. Reference range:
serum/plasma;
for women –2.5-6.8mg/dl
for men –3.6-7.7mg/dl

20. Urea is the chief nitrogenous waste of body.
Urea is the end product of protein
metabolism.
After filtered by glomeruli. It is partially
reabsorbed by the renal tubules.
REFERENCE VALUE:
serum/plasma: 13-45mg/dl

21. Urea clearance test is less than the GFR and it is
influenced by the protein content of the diet.
Approximately 40% of filtered urea is normally
reabsorbed by tubules
The sensitivity of urea clearance is much less than the
creatinine clearance because plasma concentration of
urea is affected by number of factors.
Like, Dietary protein
fluid intake
infection
surgery, etc.
Normal value of urea clearance: 75% ml/min.
Urea clearance is defined as the volume(ml) of plasma
that would be completely cleared of urea per minute.

22. It is calculated by the formula:
Cm= U*V/P
Cm= Maximum Urea clearance.
U = Urea concentration in urine (mg/dl).
V = Urine excreted per minute in ml.
P = Urea concentration in plasma.
If the output of urine is more than 2ml per
minute.
This is referred to as maximum urea
clearance.

23. Standard Urea Clearance:
the urea clearance drastically changes when
the volume of urine is less than 2ml/min.
This is known as standard urea clearance(C)
and the normal value is around 54ml/min.
Diagnostic importance:
A Urea clearance value below 75% of the
normal is serious. Since it is an indicator of
renal damage.
Blood urea level is found to increase only
when the clearance falls below 50% normal.
Normal level of blood urea:20-40 mg/dl.

24. Pre-renal condition:
Dehydration, severe vomiting, intestinal
obstruction, diarrhea, diabetic coma, severe
burns, fever and severe infections.
Renal diseases:
1.Acute glomerulonephritis
2.Nephrosis
3.Malignant hypertension
4.Chronic pyelonephritis

25. Urea concentration in serum may be low in
late pregnancy, in starvation, in diet grossly
deficient in protein and in hepatic failure.
Azotemia:
Increase in the blood level of creatinine, urea,
uric acid is referred to as azotemia and is the
hallmark of kidney failure.

26. Glomerular filtration rate(GFR) is the volume
of fluid filtered from the renal(kidney)
glomerular capillaries in to the Bowman’s
capsule per unit time.

27. GFRisequaltotheclearanceratewhenany
solutionisfreelyfiltered&isneither
reabsorbednonsecretedbythekidneys.
GFRistypicallyrecordedinunitsofvolume
perminute
EX:millilitersperminutes(ml/min),compare
tofiltrationfraction

28. Therateatwhichplasmaisfilteredbythe
kidneyglomeruli.
Animportantmeasurementintheevaluation
ofkidneyfunction
GFR=125mlplasma/minor,180L/day
TheKidneysfiltertheplasmasome60timein
aday.

29. 1.Change in renal blood flow
2.Glomerular capillary hydrostatic pressure
3.Change in capsular hydrostatic pressure
4.Oncotic pressure
5.Glomerular capillary permeability
6.Effective filtration surface area
7.Size, shape & electrical change of the
macromolecules

30. 1.Nephrotic syndrome
2.Nephritic syndrome
3.Single kidney

31. Measurement or calculation of the
glomerular filtration rate (GFR)
Considered the most sensitive chemical test
for assessing function
Collect a24 hour or timed urine specimen &
a blood specimen from the patient
Measure the creatinine in the serum urine
specimen
Calculate the clearance

32. eGFR=30849.2 X (serum creatinine)-
1.154(age)-0.203
If female then multiplied by 0.742

33. Normal GFR is approximately 125 mL/min.