Unexpected Hyperparathyroidism in A Patient With Acrodysostosis

ABSTRACT Objective Acrodysostosis is a rare skeletal dysplasia with one gene mutation associated with pseudohypoparathyroidism. We describe a 15-year-old male patient with genetic acrodysostosis who presented with hyperparathyroidism. Methods Laboratory testing, including genetic testing for acrodysostosis and biochemical evaluation for hypercalcemia, were obtained. For evaluation of the source of hyperparathyroidism, parathyroid imaging including technetium (99mTc) sestamibi (MIBI) scan, ultrasound, and 4-dimensional computed tomography scans were performed. Results The initial calcium level of 11.7 mg/dL (reference range is 8.4 to 10.2 mg/dL), phosphorus of 2.6 mg/dL (reference range is 2.9 to 5.0 mg/dL), and parathyroid hormone (PTH) of 177 pg/mL (reference range is 15 to 65 pg/mL) were suspicious for hyperparathyroidism. Magnesium, albumin, creatinine, and PTH-related peptide levels were normal. His calcium/creatinine ratio was 0.15, calcium/creatinine clearance ratio was 0.008, and the fractional excretion of phosphorus was 34%. Our patient had no symptoms other than long-standing bone pain. Thyroid ultrasound then MIBI scan did not show a parathyroid adenoma or parathyroid gland hyperplasia. Familial hypocalciuric hypercalcemic syndrome was entertained, but without a family history and documented normal calcium levels throughout childhood, it was considered unlikely. On subsequent testing, his calcium and PTH levels increased. Subsequent imaging including repeat thyroid ultrasound, MIBI scan, and computed tomography did not find a definitive cause. Multiple endocrine neoplasia type 1 genetic testing was negative. Without an adenoma seen to remove surgically, we performed a trial of cinacalcet with successful reduction in PTH and normalization of his calcium and phosphorus levels. Conclusion Pseudohypoparathyroidism and hypocalcemia are well reported in acrodysostosis. To the best of our knowledge, this is the first reported case of hypercalcemia caused by hyperparathyroidism in a patient with acrodysostosis. Abbreviations cAMP cyclic adenosine monophosphate FHH familial hypocalciuric hypercalcemia GPCR G-protein-coupled receptor MIBI technetium (99mTc) sestamibi PTH parathyroid hormone TSH thyroid-stimulating hormone