Improving the diagnostic reliability of rapidly fluctuating plasma hormone levels by optimized multiple-sampling techniques.

When plasma hormone levels undergo rapid and large oscillations, as in the case of testosterone, FSH, and LH, a single random sample is likely to yield a result within +/-20% of the true mean value only 68%, 54%, and 30% of the time, respectively. Multiple sampling increases reliability, and computer analysis demonstrates that three equally-spaced samples taken at 6 to 18 min intervals provide the optimum schedule, given certain practical considerations. Pooling of the three plasma samples prior to radioimmunoassay avoids an increased laboratory workload.