rickets

Rickets is a disorder of growing bones in children characterized by defective mineralization of osteoid at the growth plates. It typically arises from vitamin D deficiency, but can also result from abnormalities of calcium or phosphate metabolism. The consequence is soft, weakened bones and skeletal deformities. In adults, a similar process is called osteomalacia, which affects mature bone rather than the growth plates.

Causes and risk factors include insufficient sun exposure, inadequate dietary vitamin D or calcium, malabsorption, liver or kidney disease, and genetic disorders that affect phosphate handling (hypophosphatemic rickets). At-risk groups include exclusively breastfed infants without vitamin D supplementation, toddlers, individuals with dark skin living in northern latitudes, and patients with conditions that impair absorption or renal phosphate wasting.

Clinical features commonly include slowed growth, bowed legs or other skeletal deformities, enlargement of the costochondral joints (rachitic rosary), craniotabes, dental abnormalities, and muscle weakness. Diagnosis is based on clinical suspicion supported by radiographs showing metaphyseal cupping and fraying, and laboratory tests typically revealing low calcium and phosphate, elevated alkaline phosphatase, and elevated parathyroid hormone; low 25-hydroxyvitamin D confirms deficiency in many cases.

Treatment aims to restore vitamin D and mineral balance and address underlying causes. Standard approach includes vitamin D supplementation (eg, cholecalciferol or ergocalciferol) with adequate calcium intake; in renal or phosphate-wasting conditions, active vitamin D and phosphate management may be required. Early treatment improves outcomes and can prevent lasting deformities.

Prevention focuses on vitamin D supplementation for at-risk infants and children, safe sun exposure, and consumption of fortified foods. The prognosis is favorable with prompt treatment, though severe deformities may persist if therapy is delayed.