Hiperparatiroidismo terciario en el raquitismo hipofosfatémico. A propósito de un caso

El raquitismo hipofosfatémico se caracteriza por la pérdida renal de fosfato y déficit relativo de 1,25 (OH)2D3, y se presenta como deformidades esqueléticas y retraso del crecimiento.

Hypophosphatemic rickets is characterized by the loss of renal phosphate and a relative 1,25 (OH)2D3 deficiency; it presents in the form of skeletal deformities and retarded growth. A case of tertiary hyperparathyroidism is reported in a 10-year-old boy who had been diagnosed as having hypophosphatemic rickets at the age of 3 years and been treated with high-dose phosphorus and vitamin D. The patient presented retarded growth and diverse malformations. Laboratory studies disclosed the presence of hypo phosphatemia with normal calcium levels and elevated phos phatases. The radiological examination revealed osteoporosis, osteomalacia and evidence of rickets involving the metaphyses. The resulting diagnosis was familial hypophosphatemic rickets and the patient was treated uninterruptedly for 7 years with a combination of phosphorus and vitamin D. He deve loped hypercalcemia (Ca: 14 mg/dl) and an elevated PTH (76 pg/dl) which suggested the presence of tertiary or autonomous hyperparathyroidism, and additional tests were performed to confirm it. Ultrasonographic images of the neck showed small nodules in the inferior parathyroid glands and gamma scintigraphy with thallium-technetium disclosed bilateral parathyroid gland abnormalities. With the diagnosis confirmed, the patient underwent subtotal parathyroidectomy, the outcome of which was favorable. Prolonged phosphate administration can induce secondary hyperparathyroidism, which may progress to autonomous or tertiary hyperparathyroidism. These situations are refractory to medical treatment and require surgery of the parathyroid glands to normalize the PTH and calcium levels