Osteomalacia and Rickets

Vitamin D (cholecalciferol) Sources of vit D Diet u.v. light on precursors in skin Normal daily requirement 400-800 IU/day Target organs bone - increased Ca release gut - increased Ca absorption

Normal metabolism Vit D 25-HCC (Liver) Ca/PTH 1,25-DHCC 24,25-DHCC (Kidney) (Kidney)

Actions of vitamin D Kidney Bone Small bowel decreased Ca2+ excretion increased bone mineralization Small bowel increased Ca2+ and PO42- absorption

Osteomalacia Equivalent to Rickets in children Definition: Inadequate mineralization of bone less mineralization per unit volume of bone

Osteomalacia: causes Vit D deficiency Abnormal vit D metabolism low intake plus inadequate sunlight exposure malabsorption Abnormal vit D metabolism Liver disease Renal disease Drugs (anticonvulsants) Hypophosphatemia Low intake Genetic

Vitamin D Deficiency risk factors Infancy Elderly individuals with minimal sun exposure Dark skin Skin covering when outside Fat malabsorption syndromes Kidney failure Genetic disease Epilepsy (phenytoin, phenobarbitones)

Osteomalacia: clinical manifestations malaise Bone pain Proximal muscle weakness Abnormal gait (waddling gait) Hypocalcaemia

Osteomalacia: Diagnosis Ca P ALP Urine Ca PTH

Rickets

frogleg view looser’s zone AP view looser’s zone

Normal Osteomalacia

Osteomalacia: Treatment Treatment of Vitamin D deficiency is replacement! Oral vitamin D replacement Adults require~ 400IU/day Elderly~ 800IU/day (# prevention) Ca P