Lab 5 Renal Function test RFT Part 2

Lab (5): Renal Function test (RFT) (Part 2) T. A Nouf Alshareef nf. shareef@hotmil. com KAU-Faculty of Science- Biochemistry department Clinical biochemistry lab (Bioc 416) 2012

Creatinine • Creatinine is by-product of muscle energy metabolism that it is a waste product and filtered from the blood by kidneys and then excreted into the urine. • Production of creatinine depends on an individual's muscle mass, which is usually constant. • Its level considered a sensitive renal function marker.

Serum creatinine: • In renal failure, the level of creatinine is elevated in blood and decreased in urine because kidney unable to excrete creatinine in urine. • Elevated blood creatinine is a more sensitive indication of impaired kidney function than the BUN: Ø Its level only effected by muscle mass which is usually constant Ø creatinine level is very little affected by liver function

BUN/Creatinine ratio: - BUN-creatinine ratios increase with renal disease. - effected by other factors as: liver function, muscle mass, dietary protein High BUN-to-creatinine ratio: Low BUN-to-creatinine ratio: • Sudden acute kidney failure. • Low protein diet • Urinary tract blockage (kidney stone). • Severe muscle injury. • Very high ratio may be caused by bleeding in the digestive tract or respiratory tract.

Glomerular Filtration Rate (GFR): • is the rate (volume per minute) at which the filtration of blood is performed by the glomerulus and transferred to Bowman's space. • It is determined practically by measuring creatinie clearance.

Creatinine clearance: • is the volume of blood plasma that is cleared of creatinine per unit time (expressed in ml/min). • It measures GFR • Normal range: man: 120 ml/min women: 100 ml/min

v If GFR less than 60 ml/min: for 3 months the patient has chronic kidney disease CKD. v If GFR is less than 10 ml/min: this stage is called end-stage kidney disease or end-stage renal disease (ESRD). • End stage means kidneys can’t filter chemicals and minerals out of blood. • In this stage patient needs dialysis or kidney transplant.

According to the value of GFR, kidney disease is classified to five stages: Stage of kidney disease 1 2 3 4 5 Normal Mild reduced Moderately reduced severely reduced Kidney failure 120 90 30 10 60 Glomerular Filtration Rate (approximate percent of kidney failuar)

Creatinine clearance calculation: • can be calculated without a 24 hour urine collection using: • serum creatinine concentration • sex, age, and weight Cockroft equation: (Weight in Kg, creatinine in μmol/L, constant: men = 1. 23, women= 1. 04)

Experiment: Measuring creatinine and Creatinine Clearance Principle: Creatinine + Picrate Alkaline Yellow-red complex • The rate of formation of colored complex is directly related to creatinine conc.

Kit components

Sample: • Serm or urine

Procedure:

Calculations

Normal Range Can you calculate creatinine clearance ? ? ?