Calcium and platelets in normotensive and hypertensive human pregnancy.
OBJECTIVE
The primary objective of this study was to determine the baseline platelet intracellular free Ca2+ concentration in normotensive and hypertensive primigravid women and to note any correlation between variables (ie. platelet intracellular free Ca2+ concentration and arterial blood pressure).


METHODS
A cross-sectional study of 24 normotensive and 36 primiparous women whose pregnancies were complicated by gestational hypertension, in the third trimester.


METHODS
Platelet intracellular free Ca2+, serum Ca2+, and renal clearance of Ca2+ were recorded.


RESULTS
Mean platelet intracellular free Ca2+ concentration was significantly increased in those subjects whose pregnancies were complicated by proteinuric gestational hypertension (pre-eclampsia) compared with the normotensive primiparous control sample. Those subjects with non-proteinuric pregnancy-induced hypertension did not show this significant increase in baseline platelet intracellular free Ca2+ concentration despite having a persistent and statistically significantly elevated systemic arterial blood pressure. On pooling these data for both normotensive and hypertensive primigravidae a significant positive correlation was noted between the variables of platelet intracellular free Ca2+ concentration and arterial blood pressure. The renal clearance of free Ca2+ was progressively reduced with increasing severity of the disease but had returned to normal 6 weeks postpartum. Serum Ca2+ concentrations corrected for albumin were however higher in the hypertensive patients.


CONCLUSIONS
Transmembrane Ca2+ fluxes are altered in hypertensive pregnancy by a specific mechanism, probably of placental origin.
Kilby
M D
MD
Department of Obstetrics and Gynaecology, University Hospital, Queens Medical Centre, Nottingham, UK.
Broughton Pipkin
F
F
Symonds
E M
EM
D000328:Adult; D001792:Blood Platelets / Q000378:metabolism*; D002118:Calcium / Q000097:blood*; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D006973:Hypertension / Q000097:blood*; D007474:Ion Exchange; D010976:Platelet Count; D049590:Postpartum Period / Q000097:blood; D011225:Pre-Eclampsia / Q000097:blood; D011247:Pregnancy / Q000097:blood*; D011249:Pregnancy Complications, Cardiovascular / Q000097:blood*; D011263:Pregnancy Trimester, Third
D002118:Calcium