The Anterior Pituitary, Snakebite and Sheehan's Syndrome

Abstract

In Burma, Russell's viper bite is a major public health problem, especially in rice field workers. Death frequently occurs from renal and cardiac failure. Prompted by observation of hypoglycaemia and reported necropsy findings of pituitary damage after Russell viper bite, Warrell and his co-workers in Rangoon succeeded in showing pituitary function defects in the victims [1], despite the difficulties with studies of acute illness in a rural background. Now the Hammersmith group [2] with a different set of Burmese researchers have confirmed the findings, showing bite by this viper to be a common cause of anterior pituitary failure in Burma. Between them the two groups have studied 36 long-term survivors, and have found frequent clinical evidence of pituitary hormone failure. This is supported by firm laboratory evidence in patients not on replacement for the hormone concerned, as follows: low testosterone in 16 of 33 tested, oligoor amenorrhoea in two of two, low thyroxine in 13 of 34, cortisol response to hypoglycaemia <500 nmol/1 in 10 of 14, and GH response to hypoglycaemia <20 mU/1 in 15 of 17. Showing the contribution of acute pituitary failure to morbidity and mortality in the acute illness is more difficult. All but one of the 20 patients of Proby el al. studied acutely had (sensibly, and presumably following the previous report of Tun-Pe et al.) been given large doses of corticosteroids before the samples were drawn for hormone analysis. The resulting suppression of the normal cortisol and growth hormone responses to severe acute illness makes it impossible to assess agonal levels of these hormones except in the few patients who had (normal) elevated levels. Similarly suppression of gonadotrophin function and lowering of T4 levels by both the severe acute illness and the steroids is admitted by Proby et al., and makes those measurements uninterpretable also. That the extent of the lowering of T4 or steroid levels indicates pituitary failure, rather than the effects of acute illness plus steroids, is not a legitimate plea a control group matched for severity and therapy would be required. Neither is hypoglycaemia recorded by Proby et al., again perhaps because of the steroid support given. However the samples showing pituitary insufficiency drawn by Tun-Pe and co-workers were taken before any corticosteroid therapy, and they also showed hypoglycaemia in three of seven patients tested. There is no doubt about the occurrence of acute anterior pituitary failure within hours of Russell's viper bite. The empirical use of high-dose steroids in India rests not on this, but on reduced mortality in rats [3].