Daily Variability in Mineral Metabolites in CKD and Effects of Dietary Calcium and Calcitriol

Clinical Journal of the American Society of Nephrology, 05/09/2012

Isakova T et al. – Short-term treatment with calcitriol and dietary calcium supplementation normalizes the parathyroid and calcemic postprandial responses in patients with CKD, in whom the diurnal rhythms of mineral metabolites are preserved.

Methods

  • Twelve CKD patients received calcitriol (0.25 μg daily for 1 week) with hourly assessments of mineral metabolites made throughout the day and in the context of standardized meals before and after treatment.
  • Calcium content (250 versus 500 mg) in the breakfasts constituted the dietary calcium intervention.
  • Twelve healthy volunteers were used as controls.

Results

  • At baseline, compared with controls, fasting CKD subjects had higher parathyroid hormone and fibroblast growth factor 23 levels and greater fractional excretion of phosphate.
  • After breakfast, urinary calcium excretion increased and parathyroid hormone levels dipped transiently in both groups, but they rose soon thereafter, reaching higher peaks in CKD.
  • Calcitriol decreased fasting parathyroid hormone levels, and when combined with dietary calcium load, it normalized the postprandial parathyroid and calcemic responses.
  • Daily variability in mineral metabolites was preserved in CKD before and after calcitriol.
  • Fibroblast growth factor 23 levels increased after calcitriol, although the response was heterogeneous.

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