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After 245,000 free vitamin D tests, 121,000 supplemented, but only 5,400 had 2nd test – Oct 2011

Vitamin D Status in Israeli Subjects before the Initiation and after the Cessation of Vitamin D Supplements.

Calcif Tissue Int. 2011 Oct 2.
Saliba W, Barnett O, Rennert HS, Lavi I, Rennert G.
Department of Community Medicine and Epidemiology, Carmel Medical Center, Clalit Health Services, and Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, 7 Michal St., 34362, Haifa, Israel, saliba_wa at clalit.org.il.

Vitamin D supplements are often recommended to restore sufficiency, although the adherence to treatment is low. This study assessed vitamin D status at different time intervals following the cessation of treatment. The database of Clalit-Health-Services (CHS), a not-for-profit HMO covering more than half of the Israeli population, was retrospectively searched for all members with available serum 25OHD test results in 2009 (245,493). We then identified those who filled any cholecalciferol prescription in 2008-2009 (121,817).

Subjects were included in the final analysis only if they started treatment in 2009, had serum 25OHD < 50 nmol/l before the first prescription in 2009, and had at least one additional test result after the last dated prescription in 2009 (5,461).

Serum 25OHD increased from 32 ± 11 nmol/l at baseline to 58.6 ± 22.3 nmol/l after treatment (P < 0.001).
( 13 ng ==> 23 ng)

The proportion of subjects with sufficient vitamin D after treatment increased with increasing cholecalciferol daily dose and treatment duration (P < 0.001) and decreased with increasing time from cessation of treatment (P < 0.001).

The effect of time from treatment cessation persisted after controlling for baseline serum 25OHD, daily cholecalciferol dose, treatment duration, seasonality, gender, age, ethnicity, and BMI; the ORs for sufficient vitamin D were 2.02 (95% CI 1.66-2.45), 1.67 (1.39-2.01), and 1.23 (1.04-1.47) for >30-60, 61-99, and 100-155 days compared to >155 days, respectively. Long-term vitamin D treatment is needed to maintain sufficient levels in those with baseline serum 25OHD below 50 nmol/l.

PMID: 21964950

Many questions from Vitamin D Wiki as a result of this study, answers by the author

Q1) Did people and doctors feel that the supplementation level was so small that there was very little chance of overdose?
   This a database based study, but given the used doses, I guess the response to the question is likely to be yes
Q2) Could the people get follow-up vitamin D testing elsewhere at less cost/hassle?
   Yes, but this is not practical because blood tests are free of charge in the CHS
Q3) Did only those people who were still feeling poorly get the followup test? (the ones who had enough vitamin D to feel good did not get a follow-up)
   Not necessarily, but this can not be answered from this cross-sectional study
Q4) Could the people get vitamin D without having to get a prescription?
   Yes over the counter. This is one of the limitations of the study, see the discussion
Q5) Were there some people who got a second test without getting a prescription?
   Sure, but these subjects were not included as this was beyond the scope of the present study

See also VitaminDWiki