T3 THYROTOXICOSIS AND SECONDARY HYPERPARATHYROIDISM IN A 21-YEAR-OLD FEMALE WITH A HISTORY OF GONADOTROPININDEPENDENT PRECOCIOUS PUBERTY AND RECURRENT FRACTURES

Abstract

INTRODUCTION
McCune Albright syndrome (MAS), caused by an activating mutation in the Gs alpha membrane associated protein, is a condition with a prevalence of 1:100,000-1:1,000,000. Diagnosis is usually established clinically by a constellation of cafe-au-lait spots, polyostotic fibrous dysplasia, and hyperfunctioning endocrinopathies. We report a 21-year-old female with cafe-au-lait spots, history of gonadotropin-independent precocious puberty, recurrent fractures, presenting with bone pain and symptoms of hyperthyroidism.

CASE
A 21-year-old female presented with symptoms of palpitations, tremors and heat intolerance. Testing revealed T3 thyrotoxicosis (suppressed TSH, elevated fT3, normal fT4), with radiographic findings of ground-glass appearance and endosteal scalloping of the humerus, ribs, and femur characteristic of fibrous dysplasia. The presence of decreased phosphorus, total calcium, 25-OH Vitamin D, and an elevated PTH level signified associated secondary hyperparathyroidism.

CONCLUSION
T3 thyrotoxicosis and secondary hyperparathyrodisim caused by vitamin D deficiency and renal phosphate wasting are common endocrinopathies associated with MAS. Both contribute significantly to the progression of fibrous dysplasia. Management is usually palliative and no form of therapy to date affects the natural course of disease.