Brief review of pathological tests.

1. Presented By:
Uzma Batool

4.  Kidneys are the organ that filter waste
products from the blood.
 The kidneys serve three essential function:
1. They function as filter, removing metabolic
product and toxins from the blood and
excreting them through the urine.
2. They regulate the body’s fluid status,
electrolyte balance and acid-base balance.

5.  Renal function tests are use to detect the
presence of renal diseases and assess their
progress.

6.  Renal function may be assessed by measuring
blood urea and serum creatinine. Renal
function decreases with age , which must be
taken into account when interpreting test
values.
 These tests primarily evaluate glomerular
function by assessing the glomerular
filtration rate.

7.  In many renal diseases, urea and creatinine
accumulate in the blood because they are not
excreted properly.
 These tests also aid in determining drug
dosage for drugs excreted through the
kidneys.

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

10.  In the muscles creatine is converted to creatine
phosphate which becomes the source of a high
energy phosphate bond for the immediate
reformation of ATP.
 Creatinine is the byproduct of muscle energy
metabolism and is produce at a constant rate
according to the muscle mass of the individual. It is
the substance that is easily excreted by the kidney.
 By this method we can also estimate serum
creatinine and urine creatinine.

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 (acute arthritis)
- chemotherapy & radiation
- leukemia(bone marrow disorders)
- hypoparathyroidism
- kidney disorders(stones)
- metastasized cancer

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.  GFR is equal to the clearance rate when any
solution is freely filtered & is neither
reabsorbed non secreted by the kidneys.
 GFR is typically recorded in units of volume
per minute
 EX: milliliters per minutes(ml/min), compare
to filtration fraction

28.  The rate at which plasma is filtered by the
kidney glomeruli.
 An important measurement in the evaluation
of kidney function
 GFR = 125 ml plasma/min or, 180 L/day
 The Kidneys filter the plasma some 60 time in
a day.

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 a 24 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.