Rickets.

Rickets remains one of the most common nontransmissible pediatric diseases, especially in low- to middle-income countries. Rickets is characterized by impaired mineralization of growing bone resulting in bone frailty, deformities, impaired growth and development, and pain with standing or walking. Nutritional rickets is the most common cause of bone disease in the world. The most frequent etiology of rickets is vitamin D deficiency, with pathognomonic biochemical and radiologic characteristics. However, even in the context of appropriate vitamin D levels, other causes for rickets need to be considered, such as decreased calcium intake or absorption, metabolic bone disorders, abnormal phosphorus metabolism, and specific genetic forms that are not responsive to vitamin D therapy. Biochemical tests measuring serum and urine calcium and phosphorus, vitamin D, alkaline phosphatase, and parathyroid hormone allow differentiation between various forms of rickets. Treatment of rickets helps optimize growth and reduce disability. Nutritional rickets is treated with vitamin D repletion, most commonly with ergocalciferol. The treatment of hypophosphatemic rickets depends on the etiology of the condition and may include calcitriol, phosphorus, and, more recently, burosumab.