Abstrait

Positive and negative false estimates of serum creatinine

Prabhat K Nigam and Abhilash Chandra

Accurate and precise measurement of serum creatinine is very important for assessment of kidney function. However, false estimates of serum creatinine have been found due to interference by both exogenous and endogenous substances which have been attributed to factors such as decreased or inhibited tubular secretion of creatinine, interference with serum creatinine assays and increased production of creatinine. Several drugs cause positive and negative interference through these mechanisms resulting in false positive and negative estimates of serum creatinine which may affect glomerular filtration rate (GFR) calculation also. Endogenous substances also affect the creatinine assay systems resulting in false estimate of serum creatinine concentration. Therefore, the awareness about the drug-induced or endogenous substance-induced false estimates of serum creatinine and preanalytical errors in blood sampling is important. Some remedial measures to avoid these interferences are: (i) avoiding blood draws from indwelling catheter, (ii) giving preference to fasting blood specimen and (iii) selecting the suitable analytical method for creatinine estimation (based on the information about the drugs being given to the concerned patient).