Osteomalacia and Rickets

OSTEOMALACIA AND RICKETS

Osteomalacia and rickets are both characterized by decreased mineralization of newly formed bone. They are usually caused by deficiency or abnormal metabolism of vitamin D. Specific causes include dietary deficiency of vitamin D, intestinal malabsorption, lack of sunlight, and renal and liver disease. Treatment is vitamin D and calcium supplementation.

Osteomalacia (adults) is due to impaired mineralization of the osteoid matrix result-ing in thin, fragile bones susceptible to fracture. The patient may present clinically with bone pain or fractures (vertebrae, hips, and wrist). X-rays show transverse lucencies called Looser zones. Lab studies show low serum calcium, low serum phos-phorus, and high alkaline phosphatase.

Rickets (children) occurs in children prior to closure of the epiphyses. Both remod-eled bone and bone formed at the epiphyseal growth plate are undermineralized. Enchondral bone formation is affected, leading to skeletal deformities. Skull defor-mities include craniotabes (softening, seen in early infancy) and frontal bossing (hardening, later in childhood). The “rachitic rosary” is a deformity of the chest wall as a result of an overgrowth of cartilage at the costochondral junction. Pectus carinatum, lumbar lordosis, bowing of the legs, and fractures also occur.