Endocrine Abstracts

JOINT3289

Introduction: Pseudohypoparathyroidism (PHP) refers to a group of heterogeneous disorders defined by targeted organ unresponsiveness to PTH characterized by endocrine abnormalities (hypocalcemia, hyperphosphatemia and elevated PTH concentrations), abnormal physical characteristics and neurocognitive deficits. The are several types: type 1 PHP (1a, 1b, 1c), type 2, pseudo-pseudohypoparathyroidism, and other forms (acrodysostosis)

Case report: A 45-year-old man was referred to the endocrinology department from orthopaedic department due to an elevated PTH concentration in the blood test (1,385 pg/mL) with normocalcaemia, normophosphatemia, normal creatinine, and low 25-(OH) vitamin D after a fall with damage in the right forearm\. The x-ray showed a lytic lesion in the epiphysis of radius, another in the metacarpus of the third finger and brachydactyly. The biospy showed a benign lesion with giant cells (giant cell granuloma). A bone gammagraphy showed other lesions in the knees, shinbone and tarsus suggestive of brown tumors. A bone densitometry showed a Z-score -2.8 at the spine and -2 at the hip. The 24-hour urine calcium was normal. He had hypothyroidism diagnosed ten years ago and suffered a fracture of his left ankle fifteen years ago. He was taking levothyroxine and 25-(OH) vitamin D supplements. His height was 173 cm and his weight 82 Kg. He had peculiar facial features and hands. He did not have children. Therefore, we suspected a PHP and we requested a genetic test, a complete hormonal test and started treatment with calcitriol. The genetic test was compatible with PHP type 1b, with a loss of methylation in GNAS A/B located within the differentially methylated region (DMR1) in the GNAS complex locus. No other hormonal abnormalities were found A bone densitometry performed nine months later showed an improvement in the Z-score: Z-score -1 at the spine and -1.7 at the hip. The dose of calcitriol was increased up to two micrograms/day to maintained the PTH levels (111 pg/mL) at the upper level of normal range (28-115 pg/mL)

Conclusions: It is important an early diagnose and treatment in patients with PHP to avoid long-term bone damage and perform genetic counseling Calcitriol is an effective and safe treatment in normocalcaemic patients with PHP like ours