A predictive equation to guide vitamin D replacement dose in patients – Full Text
Journal of the American Board of Family Medicine, 07/10/2014 Exclusive Author Commentary
Review Article
Singh G, et al. – The recommended daily allowance for vitamin D is grossly inadequate for correcting low serum concentrations of 25–hydroxyvitamin D in many adult patients. About 5000 IU vitamin D3/day is usually needed to correct deficiency, and the maintenance dose should be ≥2000 IU/day. The required dose may be calculated from the predictive equations specific for ambulatory and nursing home patients.
Gurmukh Singh, MD, PhD, MBA (07/10/2014) comments:
Vitamin D is essential for bone health and may be instrumental in non-bone health issues as well. Most adults in the USA appear to be deficient in vitamin D as measured by blood levels of 25-OH vitamin D. In patients seeking healthcare, the response to recommended daily allowance of vitamin D is generally inadequate. In analyzing the records of response to vitamin D administration in over 1300 patients, we discovered that about 5000 IU/day of vitamin D, for three to six months, is needed to correct deficiency and a dose of about 2000 IU/day is needed to maintain healthy blood levels of 25-OH vitamin D. We also described an equation to predict the dose needed for a given increase in blood level of 25-OH vitamin D, based on age, BMI, serum albumin level and starting blood level of 25-OH vitamin D. We did not find race/ethnicity to be a significant factor in response to vitamin D administration. Nursing home residents need higher doses than ambulatory patients.
J Am Board Fam Med. 2014 Jul-Aug;27(4):495-509. doi: 10.3122/jabfm.2014.04.130306.
A predictive equation to guide vitamin d replacement dose in patients.
Singh G
Abstract
BACKGROUND:
Vitamin D is essential for bone health and probably the health of most nonskeletal tissues. Vitamin D deficiency is widespread, and recommended doses are usually inadequate to maintain healthy levels. We conducted a retrospective observational study to determine whether the recommended doses of vitamin D are adequate to correct deficiency and maintain normal levels in a population seeking health care. We also sought to develop a predictive equation for replacement doses of vitamin D.
METHODS:
We reviewed the response to vitamin D supplementation in 1327 patients and 3885 episodes of vitamin D replacement and attempted to discern factors affecting the response to vitamin D replacement by conducting multiple regression analyses.
RESULTS:
For the whole population, average daily dose resulting in any increase in serum 25-hydroxyvitamin D level was 4707 IU/day; corresponding values for ambulatory and nursing home patients were 4229 and 6103 IU/day, respectively. Significant factors affecting the change in serum concentrations of 25-hydroxyvitamin D, in addition to the dose administered, are (1) starting serum concentration of 25-hydroxyvitamin D, (2) body mass index (BMI), (3) age, and (f) serum albumin concentration. The following equation predicts the dose of vitamin D needed (in international units per day) to affect a given change in serum concentrations of 25-hydroxyvitamin D: Dose = [(8.52 – Desired change in serum 25-hydroxyvitamin D level) + (0.074 × Age) – (0.20 × BMI) + (1.74 × Albumin concentration) – (0.62 × Starting serum 25-hydroxyvitamin D concentration)]/(-0.002). Analysis of the dose responses among 3 racial groups-white, black, and others-did not reveal clinically meaningful differences between the races. The main limitation of the study is its retrospective observational nature; however, that is also its strength in that we assessed the circumstances seen in usual health care setting.
CONCLUSIONS:
The recommended daily allowance for vitamin D is grossly inadequate for correcting low serum concentrations of 25-hydroxyvitamin D in many adult patients. About 5000 IU vitamin D3/day is usually needed to correct deficiency, and the maintenance dose should be ≥2000 IU/day. The required dose may be calculated from the predictive equations specific for ambulatory and nursing home patients.
© Copyright 2014 by the American Board of Family Medicine.
Calculations for Vitamin D Dosing
Nursing Home Patients:
End serum concentration of 25-hydroxyvitamin D = 0.002(Dose [IU/day]) – 0.23(BMI) + 0.21(Starting 25-hydroxyvitamin D serum concentration) 28.28
Ambulatory Patients:
End serum 25-hydroxyvitamin D concentration = 0.003(Dose [IU/day]) – 0.21(BMI) + 0.41(Starting 25-hydroxyvitamin D serum concentration) + 1.87(Albumin [g/dL]) + 0.12(Age [years]) + 4.22