Parameter Space Classification of Solutions to a Mathematical Model for the Cortisol Secretion System in Normal Man

Abstract

There have been numerous studies describing the fluctuation of plasma corticosteroid levels in the human adult [1-3]. According to Krieger et al. [2], it has not been possible to derive from these studies statistically valid definition of normal circadian periodicity to serve as a basis for characterizing deviations observed in various patient populations. The main reason was that methodology utilized, especially with regard to frequency of sampling, has not been comparable in these studies. It has however become evident that the circadian cycles of the hormone levels in man is not a smooth curve when analyzed at short time intervals [2, 3]. Efforts to remove these peaks and valleys by averaging and weighting manipulations of the data still shows the plasma levels plotted against clock time remains a jagged line. The majority of authors considered experimental errors, sampling or dilution errors to be the likely cause but still cannot adequately explain these departure from a smooth line. It has been suggested by E. D. Weitzman, on the other hand, that the secretory bursts observed in the hormone patterns are associated with the central nervous system activity [3].