Vitamin D: too much testing and treating?

Clin Med (Lond). 2018 Jun;18(3):196-200. doi: 10.7861/clinmedicine.18-3-196.


There is clinical uncertainty as to the testing of serum 25--Hydroxy vitamin D (25[OH]D) concentrations and when to use high-dose supplementation. Data show that there has been a rapid increase in the number of tests performed within the Northumbria Healthcare NHS Foundation Trust over the past 8 years and an increase in high-dose supplementation over the past 5 years. We performed a retrospective analysis of the 25(OH)D test requests over the period from January to -October 2017. A total of 17,405 tests were performed in this time period. The overall average concentration was 57.5 nmol/L and this figure was similar across age groups, although a larger proportion of patients aged over 75 had a concentration <25 nmol/L. Test requests were classified into 'appropriate', 'inappropriate' and 'uncertain' categories based on current expert opinion. We found that between 70.4% and 77.5% of tests could be inappropriate, depending on whether the 'uncertain' categories of falls and osteoporosis are considered to be justified. Tiredness, fatigue or exhaustion was the reason for testing in 22.4% of requests. We suggest that a more rational approach to testing, and subsequent treating, could lead to reductions in costs to the healthcare system and patients.

Keywords: Vitamin D; colecalciferol; testing; treatment.

MeSH terms

  • Accidental Falls
  • Adult
  • Aged
  • Alkaline Phosphatase / blood
  • Cholecalciferol / economics
  • Cholecalciferol / therapeutic use
  • Clinical Laboratory Techniques / economics
  • Clinical Laboratory Techniques / statistics & numerical data
  • Dietary Supplements*
  • Female
  • Humans
  • Hypocalcemia / blood
  • Hypocalcemia / epidemiology
  • Hypophosphatemia / blood
  • Hypophosphatemia / epidemiology
  • Male
  • Medical Overuse*
  • Middle Aged
  • Osteoporosis / diagnosis
  • Retrospective Studies
  • State Medicine
  • United Kingdom / epidemiology
  • Vitamin D / analogs & derivatives
  • Vitamin D / blood
  • Vitamin D Deficiency / blood
  • Vitamin D Deficiency / diagnosis*
  • Vitamin D Deficiency / diet therapy
  • Vitamin D Deficiency / epidemiology
  • Vitamins / economics
  • Vitamins / therapeutic use


  • Vitamins
  • Vitamin D
  • Cholecalciferol
  • 25-hydroxyvitamin D
  • Alkaline Phosphatase