Drake T S, Kaplan R A, Lewis T A
Obstet Gynecol. 1979 Jun;53(6):746-9.
Controversy exists over whether the increase in maternal serum parathyroid hormone levels observed during the second half of pregnancy is due to autonomous parathyroid function or is secondary to changes in maternal serum ionized calcium levels. In order to study this problem further, 9 subjects were followed serially throughout normal pregnancy. Total serum calcium, ionized calcium, parathyroid hormone (PTH), calcitonin, and albumin levels were measured monthly. Six of these subjects had the studies repeated 6 weeks postpartum. Serum ionized calcium levels were found to decrease from 3.81 +/- 0.12 mg/dl to 3.63 +/- 0.18 mg/dl between 21 and 25 weeks' gestation. This decrease was significant at P less than 0.01. The ionized calcium remained in this lower range until term. A significant return to 3.77 +/- 0.1 mg/dl was observed 6 weeks postpartum. Serum PTH levels showed a significant rise after 21 weeks' gestation (P less than 0.05). No serial change in serum calcitonin was observed during pregnancy, although the mean level of the group was significantly higher than in nonpregnant controls (P less than 0.01). The increase in maternal serum PTH observed during pregnancy appears to be due in part to a decrease in maternal serum ionized calcium.
孕期后半期观察到的母体血清甲状旁腺激素水平升高是由于甲状旁腺自主功能，还是继发于母体血清离子钙水平的变化，目前仍存在争议。为了进一步研究这个问题，对9名正常孕期的受试者进行了连续跟踪。每月测量血清总钙、离子钙、甲状旁腺激素（PTH）、降钙素和白蛋白水平。其中6名受试者在产后6周重复进行了这些研究。发现血清离子钙水平在妊娠21至25周之间从3.81±0.12mg/dl降至3.63±0.18mg/dl。这种下降在P<0.01时具有显著性。离子钙在整个孕期一直保持在这个较低水平，直到足月。产后6周观察到显著回升至3.77±0.1mg/dl。血清PTH水平在妊娠21周后显著升高（P<0.05）。孕期未观察到血清降钙素的连续变化，尽管该组的平均水平显著高于非孕对照组（P<0.01）。孕期观察到的母体血清PTH升高似乎部分是由于母体血清离子钙降低所致。
