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Open access

Ana Coelho Gomes, José Maria Aragüés, Sílvia Guerra, Joana Fernandes and Mário Rui Mascarenhas

Summary

Hypogonadotropic hypogonadism (HH) is common and occurs prematurely in HIV-infected men. However, HH with very low testosterone has not been described. Three men with normal pubertal development and HIV1 diagnosis at the ages of 22, 34 and 35 years. All complained of decreased libido, anejaculation and erectile dysfunction thirteen years, six months and one year after HIV diagnosis, respectively. Two had depressive syndrome and two were treated with antiretroviral therapy. Laboratory tests revealed isolated HH in all. Sellar and head CT scans were normal and all had normal CD4 count. They started testosterone replacement therapy, with symptoms improvement. Causes of HH in HIV-infected men include undernutrition, severe illness, drugs, pituitary dysfunction and comorbidities. Despite having none of these conditions (except two that were treated with low-dose psychotropics), our patients had HH with uncommonly low testosterone. This suggests that a different mechanism contributes to severe HH in HIV-infected men.

Learning points:

  • The pathogenesis of hypogonadotropic hypogonadism in HIV-infected men is multifactorial and androgen deficiency is more often a consequence of secondary hypogonadism than primary hypogonadism.

  • Causes of hypogonadotropic hypogonadism in HIV-infected men include undernutrition, severe illness, drugs (psychotropics, opiates, megestrol acetate or steroids), pituitary dysfunction (tumor, hyperprolactinemia), an AIDS-related lesion (very rarely) and comorbid conditions, such as antibody to hepatitis C virus seropositivity and injection drug use.

  • Highly active antiretroviral therapy (HAART), particularly protease inhibitor therapy has been associated with sexual dysfunction in men, but the causal nature of this relation has not been clearly established.

  • Hypogonadotropic hypogonadism with uncommonly low testosterone levels are not usually associated with the conditions referred and this suggests that a different mechanism could contribute to severe hypogonadotropic hypogonadism in HIV-infected men.

  • Screening for hypogonadism in all HIV-infected men might help to understand its etiology.

Open access

Etienne Larger, Nicolai J Wewer Albrechtsen, Lars H Hansen, Richard W Gelling, Jacqueline Capeau, Carolyn F Deacon, Ole D Madsen, Fumiatsu Yakushiji, Pierre De Meyts, Jens J Holst and Erica Nishimura

Summary

Glucagon stimulates hepatic glucose production by activating specific glucagon receptors in the liver, which in turn increase hepatic glycogenolysis as well as gluconeogenesis and ureagenesis from amino acids. Conversely, glucagon secretion is regulated by concentrations of glucose and amino acids. Disruption of glucagon signaling in rodents results in grossly elevated circulating glucagon levels but no hypoglycemia. Here, we describe a patient carrying a homozygous G to A substitution in the invariant AG dinucleotide found in a 3′ mRNA splice junction of the glucagon receptor gene. Loss of the splice site acceptor consensus sequence results in the deletion of 70 nucleotides encoded by exon 9, which introduces a frame shift and an early termination signal in the receptor mRNA sequence. The mutated receptor neither bound 125I-labeled glucagon nor induced cAMP production upon stimulation with up to 1 µM glucagon. Despite the mutation, the only obvious pathophysiological trait was hyperglucagonemia, hyperaminoacidemia and massive hyperplasia of the pancreatic α-cells assessed by histology. Our case supports the notion of a hepato–pancreatic feedback system, which upon disruption leads to hyperglucagonemia and α-cell hyperplasia, as well as elevated plasma amino acid levels. Together with the glucagon-induced hypoaminoacidemia in glucagonoma patients, our case supports recent suggestions that amino acids may provide the feedback link between the liver and the pancreatic α-cells.

Learning points:

  • Loss of function of the glucagon receptor may not necessarily lead to the dysregulation of glucose homeostasis.

  • Loss of function of the glucagon receptor causes hyperaminoacidemia, hyperglucagonemia and α-cell hyperplasia and sometimes other pancreatic abnormalities.

  • A hepato–pancreatic feedback regulation of the α-cells, possibly involving amino acids, may exist in humans.

Open access

Motoyuki Igata, Kaku Tsuruzoe, Junji Kawashima, Daisuke Kukidome, Tatsuya Kondo, Hiroyuki Motoshima, Seiya Shimoda, Noboru Furukawa, Takeshi Nishikawa, Nobuhiro Miyamura and Eiichi Araki

Summary

Resistance to thyroid hormone (RTH) is a syndrome of reduced tissue responsiveness to thyroid hormones. RTH is majorly caused by mutations in the thyroid hormone receptor beta (THRB) gene. Recent studies indicated a close association of THRB mutations with human cancers, but the role of THRB mutation in carcinogenesis is still unclear. Here, we report a rare case of RTH with a papillary thyroid carcinoma (PTC). A 26-year-old woman was referred to our hospital due to a thyroid tumor and hormonal abnormality. She had elevated serum thyroid hormones and non-suppressed TSH levels. Genetic analysis of THRB identified a missense mutation, P452L, leading to a diagnosis of RTH. Ultrasound-guided fine-needle aspiration biopsy of the tumor and lymph nodes enabled the cytological diagnosis of PTC with lymph node metastases. Total thyroidectomy and neck lymph nodes dissection were performed. Following surgery, thyroxine replacement (≥500 μg) was necessary to avoid the symptoms of hypothyroidism and to maintain her TSH levels within the same range as before the operation. During the follow-up, basal thyroglobulin (Tg) levels were around 6 ng/ml and TSH-stimulated Tg levels were between 12 and 20 ng/ml. Up to present, the patient has had no recurrence of PTC. This indicates that these Tg values are consistent with a biochemical incomplete response or an indeterminate response. There is no consensus regarding the management of thyroid carcinoma in patients with RTH, but aggressive treatments such as total thyroidectomy followed by radioiodine (RAI) and TSH suppression therapy are recommended.

Learning points

  • There are only a few cases reporting the coexistence of RTH and thyroid carcinoma. Moreover, our case would be the first case presenting one with lymph node metastases.

  • Recent studies indicated a close association of THRB mutations with human cancers, but the role of THRB mutation in carcinogenesis is still unclear.

  • When total thyroidectomy is performed in patients with RTH, a large amount of thyroxine is needed to maintain their thyroid function.

  • There is no consensus regarding the management of thyroid carcinoma in patient with RTH, but effective treatments such as total thyroidectomy followed by RAI and TSH suppression therapy are recommended.