18.7 Calculations
Plot a graph between amount of creatinine at x-axis and absorbance at y-axis.
Extrapolate creatinine concentration of given serum/urine sample from the graph
(include dilution factor for calculation). The creatinine concentration can also be
calculated by using equation:
Amount of creatinine in blood¼
ODof testamount of standardðÞμg 100
ODof standardvolume of sample mlðÞ 1000
¼xmg=dlAmount of creatinine in urine¼OD of testamount of standardðÞμg 1000 dilution factor
OD of standardvolume of sampleðmlÞ 1000 1000¼xg=LNote 3 ml of protein-freefiltrate is equivalent to 0.3 ml serum/urine sample since
0.5 ml sample was made to 5 ml before preparing protein-freefiltrate.
18.8 Clinical Significance...............................
Normal range of creatinine in serum is 0.6–1.5 mg/dl and in urine is 90–150 mg/l of
urine. It increases in renal disease, and creatinine value goes up to 20 mg/dl in
muscular dystrophy and different types of muscular tissue diseases. Serum creatinine
level also increases in fever and starvation. There is considerable muscle wasting in
diabetes mellitus resulting in high creatinine levels. Creatinine levels are also raised
in urinary tract obstruction, due to blockage of creatinine excretion through urine.
Decrease in serum creatinine levels is seen in decreased muscle mass with aging and
in pregnancy.
78 18 To Estimate Creatinine Level in Serum and Urine by Jaffe’s Reaction