Pathophysiology of hypocalciuria in preeclampsia: measurement of intestinal calcium absorption.
OBJECTIVE
To analyze calcium absorption using stable isotopes in patients with preeclampsia and in normotensive controls.


METHODS
Fifteen pregnant subjects were studied: eight with preeclampsia (hypertension and proteinuria) and seven normotensive controls. All patients were ingesting their normal diet. The subjects received two stable calcium isotopic tracers. An oral tracer (44Ca, 0.0124 mmol/kg) was given with milk, while an intravenous tracer (42Ca, 0.00249 mmol/kg) was infused over 7-10 minutes. Calcium concentration was determined by atomic absorption spectrophotometry, and isotope ratios by thermal ionization mass spectrometry from pooled 24-hour urine samples.


RESULTS
No difference was noted in fractional intestinal absorption between preeclamptic subjects (0.282 +/- 0.051) and normotensive controls (0.306 +/- 0.079) (P = .49). However, the fraction of dietary calcium appearing in the urine differed significantly (0.06 for preeclamptic subjects and 0.087 for normotensive controls; P = .008).


CONCLUSIONS
Despite the indirect evidence of others, calcium absorption does not appear to be impaired in patients with preeclampsia. The retention site of the unexcreted calcium is unidentified.
Tolaymat
A
A
Department of Pediatrics, University of Florida Health Science Center/Jacksonville.
Sanchez-Ramos
L
L
Yergey
A L
AL
Vieira
N E
NE
Abrams
S A
SA
Edelstein
P
P
D000328:Adult; D002118:Calcium / Q000378:metabolism / Q000652:urine*; D002127:Calcium Isotopes; D002136:Calcium, Dietary / Q000493:pharmacokinetics*; D005260:Female; D006801:Humans; D007408:Intestinal Absorption / Q000502:physiology*; D011225:Pre-Eclampsia / Q000503:physiopathology / Q000652:urine*; D011247:Pregnancy
D002127:Calcium Isotopes; D002136:Calcium, Dietary; D002118:Calcium