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.

• 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.

• 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.