Serum Concentration of Parathyroid Hormone in Preeclampsia

Abstract

Background: Preeclampsia, the de novo occurrence of hypertension and proteinuria after the 20th week of gestation, continues to exert an inordinate toll on mothers and children alike. The dynamics of calcium homoeostasis are in fact substantially altered in pregnancy. Hypocalcemia and maternal hypovitaminosis D have been identified as risk factors for preeclampsia.

Objectives: To evaluate the state of parathyroid hormone (PTH) and total calcium (tCa) in women with preeclampsia in different gestational periods with respect to normal pregnancy.

Methods: Case-control study (November 2008 - March 2009) at Al-Kadhimiya Teaching Hospital. Includes measurement of serum (total calcium and PTH) in 60 patients with preeclampsia who were classified into two groups according to the gestational age: Preeclamptics in the second trimester G1: (n=30). Preeclamptics in the third trimester G2: (n=30). The results were compared with 60 apparently healthy pregnant women (as controls). They were classified according to the gestational age into two groups: Pregnants in the second trimester G3: (n=30). Pregnants in the third trimester G4: (n=30).  

Results: Significant increase in serum parathyroid hormone (p < 0.001) which is accompanied by a significant decrease in serum total corrected calcium in the preeclamptics as compared with the controls (p < 0.001). The above changes were also significant with advancing gestational age in both preeclamptic and healthy pregnants. These results can be explained partly by the inadequate local production of parathyroid hormone-related protein (PTHrP), which is involved not only in the maternal and fetal failures but also in the etiological aspects of the disease. Also, these results can be explained by the associations between calcium metabolism disturbances and primary hyperparathyroidism with preeclampsia, suggesting parathyroid involvement in preeclampsia etiology

Conclusion: Preeclamptics (in different gestational age groups) experienced disturbances in calcium homeostasis and the factors affecting this homeostasis when compared with healthy pregnant women matched with their age and gestational age. The above results were supported by the finding of significant low level of total corrected calcium which was accompanied by significant high level of parathyroid hormones. The above results call for the need for calcium supplementation and monitoring parathyroid function and maternal plasma PTHrP concentrations in pregnancy.

Keywords: Preeclampsia, Parathyroid hormone.