Time series analysis of hormonal patterns in human plasma

Methods of time series analysis were applied to half-hourly plasma levels of aldosterone, growth hormone, and renin activity in four normal volunteers and one patient (CH) with aldosterone producing adenoma. The evidence suggests that the hormonal time series of normal subjects are homologous, when their mean levels are made equal; therefore, they can be concatenated in a single series. Analysis in the time domain and in the frequency domain suggest a predominant 24-hr periodicity. Cross-correlation indicates synchrony of aldosterone with renin and of cortisol with corticosterone, suggesting common regulatory mechanisms; it also shows a 5-hr lag difference between the two pairs, indicative of their phase relation. In CH, lag-correlation and spectral analysis of aldosterone, and renin differ from the normal, those of cortisol and of corticosterone are similar to the normal group. These results indicate that time series analysis may be a useful, objective and quantitative approach to the analysis of complex hormonal patterns in plasma.