Calcium, parathyroid hormone and calcitonin in normal pregnancy and preeclampsia

Calcium, parathyroid hormone (PTH) and calcitonin (CT) in serum, and the fractional renal excretion of calcium (FECa) were determined in (1) normal pregnant women, (2) patients with preeclampsia, and (3) normal nonpregnant control subjects. Serum calcium, corrected for individual variation in serum protein, was reduced and FECa increased in the normal pregnant group when compared to the nonpregnant control group. In preeclampsia serum calcium did not differ significantly from the normal pregnant group, but FECa was considerably lower and also reduced below the level in the nonpregnant control group. PTH was slightly lower during normal pregnancy than after delivery, but did not deviate significantly from the nonpregnant control group; in preeclampsia PTH did not deviate significantly from the levels in normal pregnancy. CT was the same in the third trimester of pregnancy in both groups. Changes in serum calcium and FECa were not correlated to PTH or CT. It is concluded that both normal pregnancy and preeclampsia are accompanied by considerable alterations in calcium metabolism, that PTH and CT in both groups are mainly unchanged and at nonpregnant level, and that the increase and decrease in renal calcium excretion in normal pregnancy and preeclampsia, respectively, may be attributed to changes in kidney function.