ABSTRACT
Our objective was to determine it maternal urinary calcium excretion is altered during
treatment of mild preeclampsia remote from term with the calcium channel blocker nifedipine.
One hundred forty-eight women with mild preeclampsia were randomly allocated to treatment
with either bed rest alone (n = 64) or in combination with nifedipine (n = 84) at
26-36 weeks' gestation. All women had 24 hr urine samples collected for creatinine
clearance and calcium excretion determination prior to therapy and during treatment.
There was no difference in gestational age at the time of urine collection between
the two groups. There were no differences in 24-hr creatinine clearance and calcium
excretion between the groups prior to therapy. When followed longitudinally, there
was a significant reduction in calcium excretion within each group (p = 0.0005 control group, p<0.0001 nifedipine group). Further, a significant reduction in calcium excretion was
noted following nifedipine therapy (62 ± 94 mg Ca/24 hr) compared to the control group
(143 ± 153 mg Ca/24 hr), p<0.001. Consistent with previous studies, we have shown that progressive hypocalciuria
is a feature of preeclampsia. Further, urinary calcium excretion decreased despite
nifedipine therapy. Altered urinary calcium excretion may be less reflective of the
progression in severity of preeclampsia in patients treated with nifedipine.
Keywords
Nifedipine - preeclampsia - hypocalciuria - calcium excretion
