Expression of the α- and β-subunits of human chorionic gonadotropin by subsets of parathyroid cells in states of hyperparathyroidism

Abstract

The α‐subunit of human chorionic gonadotropin (hCG‐α) has previously been found to be expressed in hyperplasias and tumours of numerous endocrine tissues including all those involved in MEN‐I syndrome except the parathyroid glands. In the present immunohistochemical investigation of 86 patients with various states of hyperparathyroidism, expression of hCG‐α by subsets of parathyroid cells was shown in 46 cases (54 per cent) including all states of hyperparathyroidism investigated: primary adenoma (n=34, 44 per cent); uraemic secondary hyperplasia (n=34, 53 per cent); MEN‐I (n=13, 77 per cent); MEN‐II (n=2, 100 per cent); and parathyroid carcinoma (n=3, 100 per cent). Although the number of parathyroid cells expressing hCG‐α was in general low, the occurrence of numerous immunoreactive cells appeared to be concentrated in primary adenoma and MEN‐I (20 and 33 per cent of positive cases, respectively). No expression was found in ten normal control glands, except for very rare cells in one case. Expression of hCG‐α was in part associated with that of hCG‐β, which appeared to be more commonly expressed than hCG‐α in cases of secondary hyperparathyroidism. In separate experiments, Bouin fixation was found to preserve the immunoreactivity of hCG‐α and hCG‐β better than the formalin fixation used in this study, suggesting that the figures may be underestimates. These immunohistochemical results are in agreement with a previous biochemical study showing hCG‐α and hCG‐β in extracts of parathyroid tumours and extend to the parathyroid glands the otherwise ubiquitous finding of hCG‐α expression in MEN‐I‐related neoplasms. © 1998 John Wiley & Sons, Ltd.

Human chorionic gonadotropin measurements in parathyroid carcinoma

“…In the same study, selective venous catheterization in 42 patients with benign PHPT yielded tenfold gradients of PTH, as expected, but also a mild elevation of hCG α-subunit in one patient (27). In another report, immunostaining of parathyroid tissue was positive for hCG in 6 out of 31 patients with parathyroid adenomas and in 1 out of 3 cancer patients (28). These immunohistochemical data suggest that parathyroid cells can acquire the capacity to synthesize and express hCG.…”

Persistent low hCG levels beyond pregnancy: report of two cases and review of the literature

“…Ces mécanismes ne sont pas encore clairement élucidés. Bien qu'il ait été rapporté que des sous-groupes de cellules parathyroïdiennes pouvaient acquérir la capacité d'exprimer les sous-unités α et β de l'hCG en cas d'hyperparathyroïdie [33], il n'a pas été démontré de relation entre l'élévation de l'hCG et l'hyperparathyroïdie secondaire dans une population de patients hémodialysés [15].…”