Endocrine Abstracts

Introduction: Hypophosphataemic rickets (HR) is a rare genetic disorder characterized by poor growth, short desproporcionate stature and lower limb anomalies. Clinical manifestations usually appear before 1 year of age, this entity is characterised by osseus hypomineralisation, secondary to the increased expression of phosphatonins, especially FGF23, which acts in the sodium and phosphate co-transporters of the proximal convoluted tubule, inducing phosphaturia. HR exhibits AD, AR or X-linked inheritance patterns.

Objective: We present two unrelated HR case reports, with clinical radiological and laboratory studies of Hypophospataemic Rickets with osseous complications and adverse medical events.

Case reports: Case 1: 7.6-year-old girl, physical examination showed height 113 cm, weight 24 kg, arm spam 116 cm, OFC 48 cm, with disproportional short stature, genu varo, gait difficulties, asymmetric thorax; actually presenting normocalcaemic, normophosphataemia, phosphaturia, calcitriol deficiency and secondary hyperparathyroidism.

Case 2: 15-year-old girl at physical examination showed height 141 cm, weight 76 kg, with surgical antecedents, the first one in order to correct bilateral tibia deformity at age 3, and genu varum correction surgery at age 5; actually presents recidivant genu varo, normocalcaemic, hypophosphataemia, and phosphaturia.

Discussion: Hypophosphataemic rickets should be suspected in any child with disproportionate short stature, developmental delay and short, malformed legs. Only one-third are due to nutritional deficit, clinical cases presented meet clinical criteria and radiological rickets. In case 1 presents normocalcaemic, normophosphataemia indicating good control in the treatment. The case 2 has normocalcaemia, hypophosphatemia and vitamin D insufficiency, renal presenting microlithiasis and secondary hyperparathyroidism, which suggests a more aggressive disease character.

Conclusions: Due to functional complications in HR, early diagnosis and treatment is necessary, based in growth curves as well as serum values of phosphorus, calcitriol, alkaline phosphatase, and others, in order to offer an optimal medical care and prevent secondary osseous deformities.