Objective: Individual variation in hypothalamic-pituitary-adrenal axis (HPAA) function has been suggested to be important in linking small size at birth with adult cardiovascular disease and its risk factors, in particular the metabolic syndrome. Human studies have, however, so far only been performed in clinic settings, and their results have not been consistent. Our aim was to assess whether HPAA activity in everyday living circumstances is related to the metabolic syndrome and size at birth.
Design: Clinical birth cohort study.
Subjects: A total of 151 women born between 1924 and 1933 in Helsinki, Finland, with measurements at birth recorded. The subjects had previously undergone detailed clinical examinations including fasting cortisol measurement and 1 micro g ACTH1-24 and overnight 0.25 mg dexamethasone tests.
Measurements: Salivary cortisol concentration was measured during a normal 24-h period: at awakening, 15 and 30 min thereafter, at 12.00 h, 17.00 h and 22.00 h and the following morning. In addition, the following summary variables were calculated: awakening response (mean of the three awakening measurements), mean of all individual measurements, and mean, SD and contrast (a measure of blunted diurnal variability, calculated as mean of morning minus mean of 1200, 1700 and 2200) of all individual z scores.
Results: Salivary cortisol awakening response was correlated with serum fasting (r = 0.17; P = 0.04), ACTH1-24-stimulated (r = 0.32; P < 0.0001), and dexamethasone-suppressed (r = 0.29; P = 0.0004) cortisol concentrations. However, no salivary cortisol measurement was associated with any component of the metabolic syndrome (waist circumference, serum triglyceride, HDL cholesterol or glucose concentration, or blood pressure). Moreover, no correlation was observed between salivary cortisol and weight, length, ponderal index, or gestational age at birth.
Conclusions: In elderly women, cortisol concentrations in an everyday environment do not appear to be associated with the metabolic syndrome or size at birth. We propose that detecting relationships between HPAA function, prenatal events and adult disease might require a test involving HPAA stimulation.