Lab (4): Renal Function test (RFT) Lecturer Nouf Alshareef KAU-Faculty of Science- Biochemistry department Clinical biochemistry lab (Bioc 416) 2012

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 System of tubules Glmulus

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) H 2 O Elements : (Na +, K +, Cl -, Mg 2+, PO 4 ) 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

Biochemical tests of renal function Test of glumular function GFT by: Urea Creatinine Creatinine clearance Tubular function test Glucosurea aminoacidourea General test Urinlysis

 glomerular filtration rate (GFR)  urine volume  urine urea  minerals in urine  urine protein  urine glucose  hematuria  Osmolality  glomerular filtration rate (GFR)  urine volume  urine urea  minerals in urine  urine protein  urine glucose  hematuria  Osmolality  Urea or BUN.  Creatinine.  uric acid.  levels of several elements : Na +, K +, Cl -, Ca 2+, Mg 2+, H 2 CO 3 and phosphorus  Urea or BUN.  Creatinine.  uric acid.  levels of several elements : Na +, K +, Cl -, Ca 2+, Mg 2+, H 2 CO 3 and phosphorus

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. 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. BUN= 50% urea

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 + H 2 O NH 3 + CO 2 NH 3 + Salicylate + hypochlorite 2,2 dicarboxy indophenol Urease

Kit components Reagents: Sulfanalic acid reagent Sodium nitrate reagent Methanol reagent Bilirubinequavalent standard (5mg/dl T.bil; 2.5 mg/dl D.bil)

Procedure:

C C alculations Abs of Bilirubinequavelant

BUN: 5-23 mg/dl Urea: 10-50mg/dl Normal range