Jorde R, Grimnes G. Serum PTH is not a good marker for defining a threshold for vitamin D deficiency.
Endocr Connect 2020;
9:396-404. [PMID:
32412426 PMCID:
PMC7274551 DOI:
10.1530/ec-20-0067]
[Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Accepted: 04/21/2020] [Indexed: 01/23/2023]
Abstract
OBJECTIVE
In addition to its skeletal effects, vitamin D may also be important for health in general. It is uncertain what level of serum 25-hydroxyvitamin D (25(OH)D), marker of vitamin D status, is sufficient for these effects. With decreasing serum 25(OH)D levels there is an increase in serum PTH. The point at which this occurs has been considered as a threshold for vitamin D sufficiency. The thresholds found have varied widely and have mainly been based on observational studies. However, to truly establish a threshold for vitamin D effects, this has to be based on randomized controlled trials (RCTs).
METHODS
The study included 2803 subjects from a general health survey, the Tromsø study, and pooled individual person data from five vitamin D intervention studies (n = 1544). Serum parathyroid hormone (PTH) and change in PTH after vitamin D supplementation were related to serum 25(OH)D levels in steps of 25 nmol/L (<24, 25-49, 50-74, 75-99, and >99 nmol/L).
RESULTS
In the Tromsø study, in the females there was a gradual decrease in serum PTH with increasing serum 25(OH)D with no apparent plateau, whereas in the males the decrease in PTH in subjects with serum 25(OH)D >74 nmol/l was marginal. In pooled RCTs, there was a significant reduction in serum PTH by vitamin D supplementation regardless of baseline serum 25(OH)D level.
CONCLUSIONS
The use of the serum PTH-25(OH)D relation from observational studies to determine a threshold for vitamin D sufficiency is highly questionable.
Collapse