Page 92 - Clinical Biochemistry

Serum creatinine:

-Creatinine, is an endogenus spontaneous decomposition product of creatine and creatine
phosphate in muscle

-Creatinine is an end product of nitrogen metabolism and its production reflects the body total
muscle mass

Men: 0.9-1.5 mg/dl

Women: 0.8-1.2 mg/dl

Restrictions of Creatinine detection
• The increase is not related to damage severity
• High inter-individual variability: muscular mass: sex, ethnicity, age

Low plasma creatinine concentration:
• Physiological: pregnancy, children than adults, women than men
• Pathological: reduced muscle mass as starvation wasting disease, steroid therapy.

High plasma creatinine concentration:
• No pathological significance: increased muscle mass, high meat intake, exhausting

exercise, drug effects as salicylates
• Pathological: Renal causes as acute or chronic of a reduced GFR

Measurement of Plasma Creatinine is more precise than Creatinine Clearance due to:
• Timed measurement of urine volume and urine creatinine.
• Accuracy of urine collection which depend on the care with the procedure has been

explained or supervised and patient cooperation.
• This mean that large change in crcl may not reflect any real change in renal function.

Creatinine clearance is only recommended in the following conditions:
• Patients with early (minor) renal disease.
• Assessment of possible kidney donors.
• Detection of renal toxicity of some nephrotoxic drugs.