Rationale:
From October to April, sunlight levels in Norway are too low to produce sufficient vitamin D, leading to widespread deficiency. Most people should take vitamin D supplements during the winter months, such as cod liver oil or vitamin D tablets. Testing vitamin D levels is generally unnecessary but should be considered for individuals at higher risk of deficiency. This includes patients with osteoporosis, chronic musculoskeletal pain, chronic kidney disease, or conditions that impair intestinal absorption of vitamin D.
When vitamin D deficiency is confirmed and supplementation has begun, repeat testing is usually unnecessary before three months due to the long half-life of vitamin D.
References:
-
Bakke Å, Tazmini K, Pretorius M, et al. Vitamin D-mangel, Nasjonal Veileder i endokrinologi. April 2024.
-
Demay M, Pittas A, et al. Vitamin D for the Prevention of Disease: An Endocrine Society Clinical Practice Guideline. J Clin Endocrinol Metab. 12. juli 2024;109(8):1907-1947.
-
Holick MF, Binkley NC, Bischoff-Ferrari HA, et al. Evaluation, Treatment, and Prevention of Vitamin D Deficiency: An Endocrine Society Clinical Practice Guideline. J Clin Endocrinol Metab. 1. juli 2011;96(7):1911–30.
-
Nasjonalt råd for ernæring. Vitamin D i Norge: Behov for tiltak for å sikre god vitamin D-status? November 2018.