Maintenance therapy following vitamin D supplementation

• UK guidance does not state that maintenance therapy is mandatory (1,2).
  • Vitamin D supplementation can be followed with a maintenance phase which involves giving 800 to 2000 units (up to a maximum of 4,000 IU) of oral vitamin D3 (cholecalciferol) daily (1).
    • Exact regimen will vary depending on the local availability of vitamin D products. There is still no clear consensus on how long the maintenance phase should last. It would be reasonable to continue the maintenance regimen for as long as it is deemed necessary in the clinical judgement of the prescriber; this may involve assessment of whether lifestyle changes have been implemented and/or checking vitamin D levels (2).
      
• A maintenance dose averaging 2000 IU/d meets the current safe upper limit guidelines and is well below safe upper limits reported by others (3).

The lack of definitive guidance as to whether maintenance therapy is required makes management difficult for clinicians. The clinician should consult local guidance and expertise. A possible pragmatic approach might be:

• 1) if vitamin D deficiency (Serum 25OHD < 25 nmol/L) and no changes in lifestyle/diet then maintenace therapy is indicated
• 2) if vitamin D deficiency/insufficiency and changes in lifestyle/diet then remeasure vitamin D level 3-6 months after onset of vitamin replacement therapy; if check vitamin D level indicates vitamin D deficiency/insufficiency then treat with replacement vitamin D regime and then follow with maintenance therapy

Reference

• (1) Royal Osteoporosis Society (2020). Vitamin D and Bone Health: A Practical Clinical Guideline for Patient Management.
• (2) NHS Coventry and Warwickshire (2020). Vitamin D Prescribing Guidelines – Adults. Available at https://www.covwarkformulary.nhs.uk/docs/chapter09/CG019-Vitamin%20D%20Guidelines.pdf (Accessed 16 May 2022)
• (3) Bilezikian JP, Formenti AM, Adler RA, Binkley N, Bouillon R, Lazaretti-Castro M, Marcocci C, Napoli N, Rizzoli R, Giustina A. Vitamin D: Dosing, levels, form, and route of administration: Does one approach fit all? Rev Endocr Metab Disord. 2021 Dec;22(4):1201-1218. doi: 10.1007/s11154-021-09693-7.