Vitamin D therapy in clinical practice. One dose does not fit all.

INTRODUCTION: Vitamin D is given to most patients with osteoporosis particularly the elderly and those on bisphosphonates. The most widely advocated dose is 800 IU with or without calcium. Whether or not this enables all or most patients to become vitamin D replete in clinical practice is not established.

AIMS: This study investigated a large cohort of patients with osteoporosis attending a metabolic bone clinic to identify if those on vitamin D supplements were adequately treated and if those commenced on treatment developed normal vitamin D levels.

METHODS: Twenty-five hydroxy vitamin D measurements from new all patients attending a district general hospital metabolic bone clinic as part of their preclinic investigations was examined. It was noted as to whether or not they were taking calcium and or vitamin D supplements. Patients not on supplements but with a low baseline vitamin D were treated with supplements and then had a repeat measurement after at least 3 months to assess whether or not they were replete.

RESULTS: From the database of 1028 patients, 100 had preclinic and follow-up vitamin D levels. They were of average age 61 years (SD 12) with a mean baseline vitamin D of 26 nmol/l. The mean posttreatment level was 58 nmol/l (SD 25). Posttreatment vitamin D levels were < 60 nmol/l in 55%, < 50 nmol/l in 36%, < 40 nmol/l in 24% and < 30 nmol/l in 13% and < 20 nmol/l in 4%. In 41 patients on Calcichew D3 Forte two tablets per day pretreatment vitamin D was 24 nmol/l (SD 16) and posttreatment 62 nmol/l (SD 28). Of this subgroup posttreatment 41% were < 60 nmol/l, 27% < 50 nmol/l, 22% < 40 nmol/l and 10% < 30 nmol/l. Two hundred and ten patients on vitamin D treatment preclinic had a mean vitamin D level of 64 nmol/l (SD 28). One hundred and twenty-four patients already on two tablets of Calcichew D3 Forte per day had a mean of 68 nmol/l (SD 28) of whom 38% were < 60 nmol/l, 24% < 50 nmol/l, 16% < 40 nmol/l, 6% < 30 nmol/l and 3% < 20 nmol/l.

CONCLUSION: Vitamin D therapy with conventional treatment improves serum levels of 25 hydroxy vitamin D but still leaves some patients with significant insufficiency and therefore the same dose of vitamin D is not appropriate for all.