Endocrine Abstracts

Background: Two prevalent and underdiagnosed endocrine disorders are primary hyperparathyroidism and Klinefelter syndrome. The main cause of primary hyperparathyroidism is parathyroid adenoma. Less commonly multiple parathyroid hyperplasia have been described with or without genetic mutations. Klinefelter syndrome could also be seen as a genetic disorder, being a chromosomal condition.

Methods: We report an uncommon association, without any family history, between Klinefelter syndrome and primary hyperaparathyroidism caused by the affection of two parathyroid glands.

Case report: The patient is a 50 year-old man, previosly diagnsticated with Klinefelter syndrome. He was referred by the urologist because of the suggestive clinical profile. The hypergonadotropic hypogonadism was confirmed as a Klinefelter syndrome by the cartiotip analysis. At the time of diagnosis, he also had a normocalcemic hyperparathyroidism in the presence of a vitamin D deficiency. Dual-energy X-ray absorptiometry (DXA) was normal. The patient receveid testosteron replacement. There was no need for fertility assessment. 1000 IU per day were used to treat the vitamin D3 deficit. After the diagnosis, the calcium levels started to rise above normal two years later. By now, the neck ultrasound had revealed a small right hyperechoic thyroid nodule and hypoechoic images with a polar doppler signal in the lower half, posterior to the left and right thyroid lobes, indicating parathyroid adenomas or hyperplasia. Technetium 99m-MBI-SPECT confirmed bilateral enhanced radionuclide accumulation at inferior parathyroid glands. DXA reveals a small decrease in bone mineral density only in the 1/3 distal part of the radius (osteopenia). The level of metanephrines/normetanephrines and calcitonin were normal. The patient was proposed to surgery, but due to the epidemiological context of COVID-19, survaillance was the choice. For now, the level of calcium is still above the normal level, with a normal level of phosphorous and vitamin D and normal renal function. No renal stones or progressive demineralization in the DXA study were observed. Ultrasound showed a growing left parathyroid nodule and a stationary right one. The thyroid nodule is also stationary. Surgery is scheduled to be done. Genetic testing is to be performed.

Conclusion: There hasn’t been any evidence of a pathological or genetic connection between the two endocrine disorders. Our patient is scheduled for genetic testing – MEN syndrome and familial hyperparathyroidism must be ruled out in this instance, due to the enlargement of two parathyroid glands. Monitoring these rare occurrences is nevertheless essential to identify more abnormalities in the future.