Clinical laboratories have seen an increased interest in vitamin D measurements as new knowledge about the vitamin's pathobiology escalates. Clinicians now recognise that besides bone health, vitamin D insufficiency may be associated with potential health risks such as coronary artery disease, diabetes, depression, epilepsy, polycystic ovaries, musculoskeletal pain, autoimmune disease, multiple sclerosis, and cancers. While vitamin D testing and supplementation has been touted for these patients, benefit is evident only for the prevention of falls and fractures. The main form of vitamin D measured is 25-hydroxy-vitamin D (25OHD). While 25OHD assays have improved, they remain a work in progress.
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