Importance of Tracking, Season, Sunny Vacations and Supplementation for Clinical Evaluation of Serum 25-Hydroxyvitamin D LevelsRolf Jorde*, Stina Therese Sollid, Johan Svartberg, Ragnar Martin Joakimsen and Guri Grimnes
Division of Internal Medicine, The University Hospital of North Norway, 9038 Tromsø, Norway
- Corresponding Author:
- Rolf Jorde
Division of Internal Medicine
The University Hospital of North Norway
9038 Tromsø, Norway
E-mail: [email protected]
Received date: August 01, 2016; Accepted date: August 06, 2016; Published date: August 11, 2016
Citation: Jorde R, Sollid ST, Svartberg J, Joakimsen RM, Grimnes G (2016) Importance of Tracking, Season, Sunny Vacations and Supplementation for Clinical Evaluation of Serum 25-Hydroxyvitamin D Levels. Vitam Miner 5:142. doi:10.4172/2376-1318.1000142
Copyright: © 2016 Jorde R, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Objective: There has been a huge increase in numbers of serum 25-hydroxyvitamin D (25OHD) measurements in spite of uncertainty concerning the benefits of vitamin D supplementation, there is a sufficient serum 25OHD level and to interpret serum 25OHD measurements. Methods: 255 subjects who participated in a 5-years intervention study with vitamin D for the prevention of type 2 diabetes and who were allocated to placebo were included. Serum 25OHD levels were measured annually, and questionnaires on sunny vacations and vitamin D supplementation filled in. Results: The serum 25OHD levels were ~ 20 nmol/L higher in the summer than the winter months; those taking vitamin D supplements had ~ 5 nmol/L higher 25OHD levels than those not taking supplements; a recent sunny vacation increased the serum 25OHD levels 8-16 nmol/L; and there was a high degree of tracking of serum 25OHD with correlation coefficient (r) between baseline and the following annual measurements between 0.67 and 0.75. Conclusions: If considering a serum 25OHD level of 50 nmol/L as sufficient and that this level should be attained year-round, and taking season, vitamin D supplementation status and recent sunny vacation into account, a single measurement will in most situations be reliable and sufficient for making clinical decisions without need for numerous repeat measurements.