Background: Vitamin D intoxication is associated with the mobilization of skeletal calcium.
Objective: To ascertain how the resolution of vitamin D intoxication affects bone density.
Design: Case series.
Setting: Referral service for metabolic bone disease in a tertiary care teaching hospital.
Patients: Four patients with osteoporosis who were each using several nonprescription dietary supplements and were found to have fasting hypercalciuria.
Intervention: Discontinuation of use of dietary supplements.
Measurements: Serial measurement of serum levels of 25-hydroxyvitamin D, ratio of fasting urinary calcium to creatinine, and bone mineral density for 3 years.
Results: Discontinuation of use of dietary supplements resulted in the normalization of serum levels of 25-hydroxyvitamin D, the normalization of the ratio of urinary calcium to creatinine, and a mean annual increase in bone mineral density (±SD) of 1.9% ± 0.6%.
Conclusions: Occult vitamin D intoxication was detected in patients who were using dietary supplements that contained an unadvertised high level of vitamin D. Resolution of vitamin D intoxication was associated with a rebound in bone mineral density.