Androgens and osteocalcin during the menstrual cycle

The relationship between physiological variations in female sex and androge nic hormones and calciotropic hormones was investigated during the menstrua l cycle. Estradiol, progesterone, total and free testosterone, androstenedi one, immunoreactive PTH, calcitonin, osteocalcin (OC), and ionized calcium serum levels were determined throughout the menstrual cycle in a population of healthy eumenorrhoic women (n = 12; age range: 20-29 yr; mean: 24.2 yr) . The women were studied from the first day of a menstrual phase until the first day of the following menstrual phase. Cycle length was standardized o n the preovulatory estradiol peak (day 0), and values were given for the fi rst day of a menstrual phase, and days -12, -10, -8, -6, -4, -2, 0, 2, 4, 6 , 8, 10, 12, and 14 of the menstrual cycle. All subjects had a regular ovul atory cycle, as indicated by the hormonal profile. No significant cycle pha se-dependent changes in calciotropic hormones were present. Significant pos itive correlations between total testosterone (r = 0.32, P < 0.001), free t estosterone (r = 0.26, P < 0.001), androstenedione (r = 0.35, P < 0.0001), and OC were observed. The significant relations between these variables wer e confirmed by a time series analysis. For the first time, these findings i ndicate a relationship between androgens and OC serum levels during the men strual cycle. An important regulatory role of endogenous androgens in OC se cretion, bone formation, and maintenance of normal bone mineral content in the healthy eumenorrhoic woman is hence suggested.