Description
The synthesis of creatine, the precursor of creatinine, takes place primarily in the liver. After its release into the circulation, creatine is actively taken up by muscles (~98%) and other tissues. Creatinine is formed as a result of the nonenzymatic dehydration of muscle creatine. Creatinine is present in serum, erythrocytes and in all bodily secretions. Under normal circumstances, creatinine is eliminated solely by renal excretion. Only in patients with severe renal insufficiency, does extrarenal elimination of creatinine occur. Creatinine fulfils many requirements for a perfect filtration marker. It is not protein bound; it is freely filtered; it is not metabolised by the kidney; and it is physiologically inert. Although concentrations of creatinine are increased in uraemia, creatinine itself is nontoxic. In renal disease, serum creatinine values do not increase significantly until renal function has been considerably impaired.
Indications
The concentration of creatinine in serum is the most widely used and commonly accepted measure of renal function in clinical medicine. Increased levels are found in renal failure, urinary tract obstruction, shock, dehydration and reduced renal blood flow. Creatinine concentrations are affected by age and gender. See Also Creatinine Clearance, Serum & Urine Creatinine, 24 Hour Urine , Blood Urea Nitrogen, Serum and Cystatin C, Serum
Sample Type, Quantity & Conditions
1 ml Serum 1 ml K2-EDTA or Li-Heparin Plasma Stability: 7 Days at 15-25 °C 7 Days at 2-8 °C 3 Months at (-15)-(-25) °C
Special Precautions
Avoid lipemic, haemolysed, and ecteric samples.
Normal Range
0 Day - 2 Months > 2 Months - < = 12 Months > 1 Year - < = 3 Years > 3 Year - < = 5 Years > 5 Years - < = 7 Years > 7 Year - < = 9 Years > 9 Years - < = 11 Years > 11 Years - < = 13 Years > 13 Years - < = 15 Years Female > 15 Year Male > 15 Years 0.24 - 0.85 0.17 - 0.42 0.24 - 0.41 0.31 - 0.47 0.32 - 0.59 0.40 - 0.60 0.39 - 0.73 0.53 - 0.79 0.53 - 0.87 0.50 - 0.90 0.70 - 1.20