Intra-individual variation of some analytes in serum of patients with chronic renal failure.

Biological intra-individual variation in the concentration of 15 biochemical analytes in serum was estimated for 17 patients with chronic renal failure (CRF) and compared with results for apparently healthy individuals. The ratio of the average intra-individual variation in CRF patients to that in normal subjects was 1.5 to 2.0 for sodium, chloride, calcium, and creatinine; 1.2 to 1.5 for hemoglobin, total protein, albumin, globulin, uric acid, cholesterol, and alpha-amylase. The intra-individual CVs for urea, high-density-lipoprotein cholesterol, triglycerides, and alkaline phosphatase did not differ significantly between groups. The intra-individual variation of calcium and the concentration of creatinine in serum correlate significantly (r = 0.661, p less than 0.01). Individual values showed a gaussian distribution for all analytes. There was no time dependence of the intra-individual variation during a three-week interval, except for calcium and cholesterol. The estimated biological component of intra-individual variation and the analytical variation can be used to derive decision-making criteria in monitoring CRF.