DESIGN: Serum intact parathormone (PTH) concentrations were measured on samples taken before and during a variable-rate tri-sodium citrate infusion designed to 'clamp' the whole blood ionised calcium concentration 0.20 mmol L-1 below baseline for 120 min.
SUBJECTS: Six Malaysian patients aged 17-42 years with acute malaria, four of whom were restudied in convalescence, and 12 healthy controls aged 19-36 years.
MAIN OUTCOME MEASURES: Whole-blood ionised calcium and serum intact PTH concentrations.
RESULTS: The mean (SD baseline ionised calcium was lower in the malaria patients than in controls (1.09 +/- 0.06 vs. 1.18 +/- 0.03 mmol L-1, respectively; P = 0.01) but PTH concentrations were similar (3.0 +/- 1.8 vs. 3.3 +/- 1.3 pmol L(-1); P = 0.33). Target whole-blood ionised calcium concentrations were achieved more rapidly in the controls than the patients (within 15 vs. 30 min) despite significantly more citrate being required in the patients (area under the citrate infusion-time curve 0.95 (0.25 vs. 0.57 +/- 0.09 mmol kg-1; P < 0.01). The ratio of the change in serum PTH to that in ionised calcium (delta PTH/ delta Ca2+), calculated to adjust for differences in initial rate of fall of ionised calcium, was similar during the first 5 min of the clamp (132 +/- 75 x 10(-6) vs. 131 +/- 43 x 10(-6) in patients and controls, respectively, P > 0.05), as were steady-state serum PTH levels during the second hour (7.0 +/- 2.2 pmol L-1 in each case). Convalescent patients had normal basal ionised calcium levels but the lowest serum intact PTH levels before and during the clamp, consistent with an increase in skeletal PTH sensitivity after treatment.
CONCLUSIONS: There is a decreased ionised calcium 'set point' for basal PTH secretion but a normal PTH response to acute hypocalcaemia in malaria. Skeletal resistance may attenuate the effects of the PTH response but patients with malaria appear relatively resistant to the calcium chelating effects of citrated blood products.
METHODS: Low-risk women at 40 weeks' gestation undergoing membrane sweeping to expedite labor were recruited. Participants were scheduled for labor induction at 41 weeks' gestation. Transvaginal ultrasonography was performed immediately before and after membrane sweeping to measure the cervical length. Three presweep and postsweep cervical lengths were measured. The shortest lengths before and after the sweep were taken as the representative lengths. The effect of membrane sweeping on cervical length was analyzed. Multivariable logistic regression analysis was performed to evaluate the effect of cervical shortening on labor induction and the mode of delivery.
RESULTS: For the 160 participants, the mean presweep cervical length ± SD was 21.0 ± 10.0 mm; the postsweep length was 23.8 ± 10.9 mm, an average increase of 2.8 ± 0.6 mm (P < .001). Cervical shortening after membrane sweeping was noted in 53 of 160 cases (33%). Cervical shortening was associated with a reduction in all-cause cesarean delivery but not labor induction on bivariate analysis. After adjustment for maternal age, parity, presweep Bishop score, postsweep cervical length, oxytocin augmentation, epidural analgesia, and meconium-stained fluid, cervical shortening after membrane sweeping was independently predictive of a reduction in cesarean deliveries (adjusted odds ratio, 0.24; 95% confidence interval, 0.06-0.90; P = .034).
CONCLUSIONS: Membrane sweeping was associated with lengthening of the cervix. A shortened cervix after sweeping was independently predictive of vaginal delivery.