Transcript Renal Function TESTS

Lab (4):
Renal Function test (RFT)
Lecturer Nouf Alshareef
KAU-Faculty of Science- Biochemistry department
Clinical biochemistry lab (Bioc 416) 2012
[email protected]
Kidney
• Major function is Filtration
• Kidney functions:
 Eliminates products of metabolism (creatinine, uric acid, urea)
 Regulates the body balance in water and minerals.
(sodium, potassium, chloride, calcium and phosphate)
 Maintains blood volume, pressure and pH.
• Kidney damage occurs in stages that can early detected.
• Many factors can affect on kidney function leads to kidney
damage;
 Most common causes :Diabetes and high blood pressure
• Abnormal results of kidney function tests may be obtained due
to a temporary renal dysfunction.
• Therefore, the test should be performed repeatedly and
interpreted on the basis of a series of results.
Kidneys Structure
• The functional unit of kidney is Nephrone
• Each kidney contains million nephrone
• Nephrone consists from two major parts:
 Glmulus: Filtration
(it is high pressure mass of capillaries that filter blood)
 System of tubules: re-absorption
Glmulus
System of
tubules
1- Glumular:
• is capsulated with double walled capsule called Boman’s capsule
• Glomular capilary membrane consists of three layers which allows
some partials of blood to pass though but not all, blood cells and
proteins are large and can't pass
• The fluid that filtered and passed through membrane is called
filtrate
• Filtrate is diffused across Bowman’s space to tubules system
of nephrone
* Filtrate is called Plasma ultra filtrate because its
composition is as plasma except protein
What gets filtered in the glomerulus ?
Freely filtared
(filterd = passed)
• H2O
• Elements : (Na+, K+,
Cl-, Mg2+ , PO4)
• Glucose
• Urea
• Creatinine
• Insulin
Not filtred
(not passed)
• Protein
• Blood cells
2- Tubules system of nephrone
• Re-absorption of water and important particales occurs on
these tubules
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Urea or BUN.
Creatinine.
uric acid.
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levels of several elements :
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Na+, K+, Cl-, Ca2+, Mg2+,
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H2CO3 and phosphorus
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glomerular filtration rate
(GFR)
urine volume
urine urea
minerals in urine
urine protein
urine glucose
hematuria
Osmolality
•
Urea is waste product of protein metabolism, it synthesized in
liver via urea cycle then it transported by blood to kidney to be
excreted in urine.
BUN= 50% urea
• Blood urea level is sensitive but not specific indicator for renal
dysfunction, because:
 Its level is affected by dietary protein
 Other non renal causes such as heart failure and blood pressure
may effect on its level.
 Its level is elevated in last stages of renal failure after 50% of
renal function is lost.
High serum urea can indicates:
• Renal insufficiency. (due to obstruction or cancer)
• Urinary tract blockage (by a kidney stone or tumor)
• Heart failure (poor renal perfusion: low blood flow to kidney).
• Dehydration (lack of fluid volume to excrete waste products).
• High-protein diet
• Some medicines.
Low serum urea may be due to:
• Very low protein diet as in malnutrition
• Severe liver damage inhibits urea cycle, decrease urea formation
and increase free ammonia leads to hepatic comma.
• Overhydration.
• Is the end product of purine metabolism and excreted in urine.
• Purine in body comes from food and break down of body cells.
• Elevated level of uric acid in blood is one of the markers of
kidney dysfunction.
Gout:
Is disease characterized by high level of uric acid which
deposited in solid form in the joins causing arthritis.
High blood uric acid occurs in:
• Gout
• Renal failure (due to decreased excretion in urine)
• Leukemia (increased turnover of cells)
• Alcoholism
• Toxaemia of pregnancy.
• Diabetes Mellitues.
• Starvation.
• Drugs like diuretics.
Low blood uric acid occurs in:
- Liver diseases (cirrhosis)
- Renal disease that decrease renal tubular re-absorption
- Some drugs
Principle:
Urea + H2O
NH3 + Salicylate + hypochlorite
Urease
NH3+ CO2
2,2 dicarboxy indophenol
Procedure:
Calculations
Abs of Bilirubinequavelant
Normal range
BUN: 5-23 mg/dl
Urea: 10-50mg/dl