R. T. T. Yeung

Association of HLA antigens with thyrotoxic Graves' disease and periodic paralysis in Hong Kong Chinese.

The HLA‐A and ‐B antigen distribution in 132 Hong Kong Chinese patients with Graves’ disease, including 24 with thyrotoxic periodic paralysis, was compared with that in 110 controls. The HLA‐DR antigen distribution in 68 patients was compared with that in 47 controls. The prevalence of Bw46 was significantly increased in patients with Graves’ disease and with periodic paralysis. The prevalence of DRw9 was also slightly increased but not at a statistically significant level. The high prevalence of Bw46 related to patients with early age at onset whereas patients with later age at onset had a significantly increased prevalence of HLA B5. It is suggested that Graves’ disease in Chinese is due to two HLA‐associated mechanisms in which early‐onset disease is associated with Bw46 and late‐onset disease with B5.

LONG‐TERM TREATMENT OF HYPERPROLACTINAEMIA WITH BROMOCRIPTINE: EFFECT OF DRUG WITHDRAWAL

Fifty‐one patients with hyperprolactinaemia (23 with macroadenoma, 23 with microadenoma, and five with idiopathic hyperprolactinaemia) were treated with bromocriptine for 2‐12 years (4.9 ± 2.9 years, mean ± SD). During therapy, the serum PRL levels were suppressed into the normal range in all but five patients. In these five patients, despite the high circulating PRL, gonadal function returned to normal in three, while in the other two gonadotrophin reserve was impaired even before therapy. Gel chromatography showed that one of these patients had a high proportion of a large molecular weight form of PRL. Twenty‐four patients received bromocriptine as the sole method of treatment for over 2 years (3.4 ± 2.3 years). In five out of the 24 subjects (21 %), serum PRL remained normal with no clinical symptoms after prolonged drug withdrawal (1‐4 years). Twenty‐one patients received radiotherapy in conjunction with bromocriptine therapy. Of these 11 had prior surgery. After a follow‐up of 6.0 ± 3.0 years after radiotherapy, serum PRL remained within the normal range in 6 out of 21 subjects (29%), 1‐4 years after bromocriptine withdrawal. One of the patients had impaired GH response to insulin hypoglycaemia developing after radiotherapy. We conclude that prolonged bromocriptine treatment is an effective treatment for prolactinomas.

THE EFFECT OF HEROIN ADDICTION ON PITUITARY-TESTICULAR FUNCTION

The effect of heroin addiction on pituitary‐testicular function was studied in 54 active and 19 abstinent addicts and their results were compared with those of 43 age‐matched controls. Abnormal sexual function was frequently found in heroin addicts and this persisted after drug withdrawal. The mean total (mean ± SE, 18.1 ± 1.0 nmol/l) and free (0.17 ± 0.03 nmol/l) testosterone (T) levels in heroin addicts were significantly lower than those in healthy controls (total T 22.8 ± 1.1 nmol/l, P < 0.005; free T 0.30 ± 0.03 nmol/l, P < 0.005). The mean sex hormone binding globulin binding capacity was higher in heroin addicts (60.1 ± 5.2 nM) than in healthy controls (35.5 ± 2.1 nM). These hormonal changes returned promptly to normal after withdrawal. The basal LH and FSH and the responses to LHRH were comparable in the three groups studied.

Incidence of Hypothyroidism After Radioactive Iodine Therapy for Thyrotoxicosis in Hong Kong Chinese

The incidence of hypothyroidism in 1396 Chinese patients in Hong Kong treated for hyperthyroidism with 131I therapy is presented using the life-table method of analysis. One year after therapy only 6% of patients were hypothyroid, but the subsequent annual incidence was 3.5%, emphasising the need for life-time surveillance of these patients. A higher incidence of subsequent hypothyroidism was found in patients with diffuse surgical treatment, the total dose or number of doses of 131I, the severity of thyrotoxicosis and the age of the patient did not influence the rate of onset of hypothyroidism. The data suggest that in order to minimise the occurrence of hypothyroidism a lower dose of 131I per gram of thyroid mass should be used for patients with small diffuse glands.

Circulating somatostatin after oral glucose in hypothyroidism

The response of circulating somato-statin-like immunoactivity (SLI) to oral glucose and its relation to other pancreatic islet cell hormones were studied in 10 hypothyroid subjects before and after treatment. None of the patients suffered from diabetes mellitus or obesity. Compared with normal controls, the hypothyroid subjects had higher fasting and stimulated SLI levels but lower fasting pancreatic glucagon levels. Integrated glucose and insulin responses following glucose ingestion were normal, but the peak insulin réponse was delayed to 120 min suggesting impaired pancreatic β-cell response to oral glucose. On the other hand, the peak response of plasma C-peptide was higher probably because of a reduction in metabolic clearance. In both hypothyroid subjects and controls, a significant correlation was found between the maximal increment of SLI and the maximal decrement of glucagon following oral glucose. In conclusion, plasma SLI is increased in hypothyroidism. The changes in SLI may be due to either an increased hormonal secretion or a reduced metabolic clearance in hypothyroidism. This elevated SLI might contribute to the slower gastrointestinal motility observed in hypothyroidism. Our data also suggest that the reduction in glucagon secretion may be secondary to the increase in circulating SLI.

Prevention of hypoglycaemia in a patient with pancreatic microadenomatosis by a long-acting somatostatin analogue SMS 201-995.

Acute suppression of insulin secretion from pancreatic insulinomas by long‐acting somatostatin analogue SMS 201‐995 has been documented. We report the chronic use of the drug in a patient with persistent hypoglycaemia due to benign pancreatic microadenomatosis with satisfactory control of plasma glucose level and reduction of insulin production. There was no tachyphylaxis or untoward side‐effect noted during the 6‐month treatment period.