Vitamin D-Related Disorders

Abstract

This chapter discusses the more classical vitamin D-related disorders such as nutritional rickets and osteomalacia, genetic disorders of vitamin D synthesis and function. Vitamin D intoxication is also considered. The spectrum of rickets and osteomalacia includes vitamin D-related and other causes such as liver disease, malabsorption, drugs and renal diseases. A transiliac bone biopsy after tetracycline double labeling provides a certain diagnosis of osteomalacia or can exclude it. The symptoms of rickets and osteomalacia may disappear with remarkably low doses of vitamin D3 unless intestinal absorption is impaired as in celiac disease. The observation that some forms of rickets could not be cured by regular doses of vitamin D led to the discovery of rare inherited abnormalities of vitamin D metabolism or the vitamin D receptor. Vitamin D intoxication is caused by increased ingestion of vitamin D or one of its active metabolites, e.g., alphacalcidol or calcitriol.