Influence of hypertension and antihypertensive drugs on the biological intra-individual variation of electrolytes and lipids in serum.

Biological intra-individual CVs for Na+, Cl-, K+, calcium, cholesterol, high-density lipoprotein cholesterol, triglycerides in serum, and hemoglobin in blood were estimated in men with essential hypertension (EH) treated with beta-blockers and diuretics, and compared with those of normotensive men. Although in EH the mean concentrations of Na+, Cl-, K+, hemoglobin, and triglycerides were increased and that of HDL cholesterol was decreased, the average intra-individual CVs did not significantly differ between the two groups. The mean concentration of cholesterol, as well as the average intra-individual CV for it, was significantly higher in EH. There was no correlation between the intra-individual CVs for the analytes and the mean blood pressure of the individuals. Individual values were normally distributed for all analytes. There was no increase of the intra-individual CV with the lapse of time between consecutively measured values. The estimated average biological intra-individual CV was used to derive decision-making criteria for interpretation of test results observed in monitoring EH.