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

2. 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.

3. 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:
Its level only effected by muscle mass which is usually constant
creatinine level is very little affected by liver function

4. 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.
Urinary tract blockage (kidney stone).
Very high ratio may be caused by bleeding in the digestive tract or respiratory tract.
Low protein diet
Severe muscle injury.

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

6. 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: 120ml/min women:100ml/min

7. If GFR less than 60 ml/min: for 3 months the patient has chronic kidney disease CKD.
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.

8. 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 60 30 10
Glomerular Filtration Rate (approximate percent of kidney failuar)

9. 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)

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

11. Kit components

12. Sample:
Serm or urine

13. Procedure:

14. Calculations

15. Can you calculate creatinine clearance ???
Normal Range
Can you calculate creatinine clearance ???