Pulse amplitude and frequency modulation of parathyroid hormone in plasma

Inconclusive reports on pulsatile secretion of PTH in man have been published. In this study PTH was measured by intact and PTH-(44-68) assays. Central venous blood sampling was performed every 2 min in 10 healthy men between 6-9 h and in 3 male patients with osteoporosis for over 6 h. Pulsatile PTH secretion was identified for healthy men and controls. Narrow pulses and bursts of narrow pulses (broad pulse) could be distinguished. Six narrow pulses per h with 26 +/- 16 ng/L amplitude and 1 burst of narrow pulses/h were detected for the intact hormone. One narrow pulse/h with 25 +/- 12 ng/L amplitude and 1 burst of narrow pulses (broad pulse) every 2 h were found (Pulsar) for PTH-(44-68). Intact and PTH-(44-68) exhibit in part a concordant pattern. Results from 3 patients with osteoporosis show a decreased amplitude and frequency of pulsatile PTH secretion. The same decreased pattern was demonstrated in a postmenopausal osteoporotic woman. A constant decline in ionized calcium elicits major secretory episodes of PTH, and ionized calcium increases after major secretory episodes of PTH. We conclude that pulsatile secretion of PTH in healthy young men is the physiological mode of secretion. Low pulsatile secretion of PTH might be related to low turnover osteoporosis.