[Vitamin D deficiency. Easy to diagnose, often overlooked].

On the basis of five cases the typical clinical picture of patients with severe vitamin D deficiency is presented. The diagnosis can easily be mistaken and it is not uncommon that rheumatic or malignant diseases are suspected instead. By using a simple screening blood test consisting of 25-OH-vitamin D, PTH and alkaline phosphatase most cases will be diagnosed correctly. Important risk factors are reviewed, the most important being: elderly > 70 years, persons with low exposure to direct sunlight, gastrointestinal diseases and persons in anti-convulsive treatment. A treatment regimen consisting of oral supplementation of 1000-1500 mg calcium + 1000 IU vitamin D to patients with an isolated low 25-OH-vitamin D (< 20 nmol/l) is recommended. If the patient also has raised values of PTH or alkaline phosphatase an intramuscular dose of 100,000 IU ergocalciferol pr week for one month is given.