Endocrine Abstracts

A 33 year old male is being follow-up for testosterone replacement (rx) after undergoing bilateral orchidectomy. He was diagnosed with a left testicular germ cell tumor at 20-years of age needing left orchidectomy, followed by a right testicular orchidectomy 2 years later in view of a lump in his right testicle. He did not receive any chemo/radiotherapy. Pre-operative LH, FSH and testosterone levels were normal; 2.4 U/l (0.8–7.6), 3.2 U/l (0.7–11.1) and 16 nmol/l (10.5–32) respectively. HCG at diagnosis was 2.9 mIU/ml (0-2.7). He underwent normal puberty. Post bilateral orchidectomy, testosterone undecanoate 1 g IM every 12 weeks was started. Pre-treatment LH was 42.7 U/l, FSH 81.4 U/l, testosterone 2.17 nmol/l and normal hCG(1.2 mIU/ml). Serial hormone levels are shown in Table 1. The main challenging dilemmas were a detectable hCG levels, 4 years after surgery and failure of suppression of LH and FSH despite normal/high levels of testosterone (table 1). A CT-Trunk excluded the possibility of any possible residual metastatic testicular tumor, or other possible hCG-producing tumor. MRI of the pituitary was normal. This case highlights two important aspects: (i) In men with bilateral orchidectomy, the LH/FSH levels may not be suppressed when exogenous testosterone is administered after bilateral orchidectomy, despite normal/high levels of testosterone. This perhaps may be explained by the absence of the negative feedback of inhibin on LH/FSH, since both testes are removed. Similarly this is seen in post-menopausal women failing to suppress LH/FSH despite HRT, however this can be explained by the low doses of sex hormone requirements needed, which are not enough to suppress LH/FSH. (ii) the pituitary produces a sufficient amount of hCG which can be detected in serum, especially when gonadotrophins levels are high - as seen in our case where hCG was detectable when LH was at its highest (table 1). However it is important to exclude other possible sources of hCG production, especially in patients with past history of malignancy to exclude recurrency or residual tumor.