Endocrine Abstracts

: Rarely PHPT could be a part of MEN 1 (2–4.5%). Little is known about clinical differences between MEN1 related and sporadic PHPT.

Aim: To compare the clinical features of PHPT in MEN type 1 cases and sporadic PHPT.

Materials and methods: Data were obtained in 442 patients: 62 sharing MEN1 phenotype (PHPT in association with pituitary adenomas and/or gastroenteropancreatic neuroendocrine tumors) (Group-I) and 380 with apparently sporadic PHPT (Group-II). Serum Ca, intact PTH, urine Ca, 25-OH-VitD, osteocalcin, β-CTx) and BMD z-score measurements, renal ultrasonography, visualization of parathyroid glands were performed in both groups. The additional diagnostic tests (prolactin levels, ultrasound of pancreas and adrenals) were performed in patients to exclude or evaluate other than PHPT endocrine disorders.

Results: The age at diagnosis was younger in Group I (39.5 (28–51) years) than in Group II (57 (48–64) years), P<0.001. In 50% of Group I PHPT debuted before age of 40 years, whereas in Group II in 70% of patients the diagnosis was made after age of 50 years. The distribution of males/females was 1:2.6 in Group I and 2:10 in Group II. In 93% of Group II PHPT was caused by a single parathyroid adenoma, in Group I in 59.6% an enlargement of multiple parathyroid glands was observed. In 64% of iPTH was higher than upper normal range less than 2.5 times, whereas in Group II 54% was more than three times higher than normal limits. In the meantime the levels of Ca in both groups were not significantly different (P=0.28). The mild PHPT was observed in Group I more frequently than in Group II (33.8 vs 19%). PHPT presented with osteoporosis with the same prevalence in both groups, but with more frequent renal manifestations in Group II. In Group I the decrease in BMD at all sites and nephrolithiasis developed independently of the degree of PTH elevation, as opposed to Group II. Multifactorial analysis revealed the combination of moderately elevated PTH and the age at diagnosis younger than 40 years to increase the risk of MEN1-related PHPT in these patients independently of their gender and the mild course of PHPT.

Conclusion: The patients with MEN1-related PHPT are younger at the diagnosis of PHPT, have more frequently multiple enlarged parathyroid glands and show mostly mild course of disease (especially in young age) and less increased PTH compared with those with sporadic PHPT.