CALCIUM-PHOSPHORUS-MAGNESIUM HOMEOSTASIS IN WOMEN WITH THREATENED PRETERM DELIVERY

Objective: The effect of threatened preterm delivery on calcium, phosp horus, magnesium homeostasis in the third trimester of pregnancy was i nvestigated. Methods: Serum concentrations of total and ionized calciu m, inorganic phosphorus, magnesium, total protein, albumin, total estr ogens and human placental lactogen were determined in women with threa tened preterm delivery at 29-36 weeks of gestation (the studied group) and in women with uncomplicated pregnancy of the same duration (the c ontrol group). Additionally, activities of total alkaline phosphatase and heat-stable alkaline phosphatase fraction were measured. Results: Patients of the studied group compared to the control group showed dec reased concentration of total calcium (2.17+/-0.09 vs. 2.28+/-0.13 mmo l/l, P <0.0005), inorganic phosphorus (1.13+/-0.27 vs. 1.32+/-0.23 mmo l/l, P <0.001) and magnesium (0.64+/-0.07 vs. 0.70+/-0.10 mmol/l, P <0 .003); they also demonstrated decreased activity of total alkaline pho sphatase (70.8+/-23.2 vs. 81.9+/-14.9 IU/l, P <0.01) and its heat-stab le fraction (30.2+/-15.6 vs. 59.6+/-14.9 IU/l, P <0.001). In the studi ed group no difference was found in concentrations of investigated ion s and enzymes between women who delivered at term and women who delive red prematurely. Patients with threatened preterm delivery showed seru m deficiency of total calcium, phosphorus and magnesium which might be related to premature uterine contractility but does not predict prema ture labor by week 36 of gestation (66% of patients delivered at term) . Conclusion: The deficiency of minerals and lowered activity of total alkaline phosphatase is observed in women with threatened preterm del ivery. Laboratory tests of calcium-phosphorus-magnesium homeostatsis h ave limited predictive value in regard to the term of delivery in wome n with threatened preterm delivery. (C) 1997 International Federation of Gynecology and Obstetrics.