Vitamin d deficiency historically has been defined as a blood level of 25hydroxyvitamind below 25nmol/l. There is scientific debate about the optimal vitamin d blood level. Current practice in the uk, as recommended by the british paediatric and adolescent bone group, is to continue to use that as the defined level of deficiency, and to define? insufficiency? as between 25 and 50nmol/l. Some laboratories and authorities use higher levels but this current practice is based on robust evidence of b...more