FROM THE JOURNAL OF CLINICAL ENDOCRINOLOGY AND METABOLISM
In an outpatient study, seasonal variability did not have a significant effect on 25-hydroxy vitamin D and parathyroid hormone levels in patients with mild primary hyperparathyroidism, likely because of widespread high vitamin D supplement intake, according to research in the Journal of Clinical Endocrinology and Metabolism.
The study involved 100 people with primary hyperparathyroidism (PHPT) from the New York area who were enrolled between December 2010 and February 2014. The researchers defined vitamin D deficiency as a 25-OH vitamin D level <20 ng/mL, and vitamin D deficiency or insufficiency as a 25-OH vitamin D level <30 ng/mL, depending on the season of enrollment. The mean vitamin D intake among the participants was 1,493 ± 1,574 IU daily between diet and supplementary sources. Nearly two-thirds (65%) of participants took vitamin D supplements, according to Dr. Elaine Cong and her associates at Columbia University in New York (J. Clin. Endocrinol. Metab. [ doi:10.1210/JC.2015-2105 ]).
Although they documented the to-be-expected seasonal differences in sun exposure, the researchers found no significant seasonal differences in levels of 25-OH vitamin D, parathyroid hormone, markers of bone turnover, or bone mineral density, or in the prevalence of 25 OH vitamin D <20 or <30 ng/mL. While supplement users had markedly better vitamin D status than nonusers (25-OH vitamin D <20 ng/mL: 8% vs. 40%, P <.0001; <30 ng/mL: 40% vs. 80%, P = .0001; ≥30 ng/mL: 60% vs. 20%, P = .0001), the researchers noted that even nonsupplement users received vitamin D through dietary means, although the nonsupplement group was more likely to be either deficient or insufficient in vitamin D.
Patients “with PHPT in the New York City metropolitan area are following secular trends and increasing their vitamin D supplement use. Most were taking over-the-counter vitamins, and it is clearly advisable for physicians who care for PHPT patients to specifically query about supplement use,” the investigators wrote.
The investigators had no relevant financial disclosures to report.
