Monday, January 23, 2012

Daboia Envenomation and the Pituitary Gland

The Russell’s vipers (Daboia russelii and D. siamensis) inhabit South and South East Asian, they are large and dangerous and do not hesitate to bite. Tun-Pe et al. (1987) suggested that envenomation by Russell's vipers could produce a disorder that resembled Sheehan’s syndrome. They investigated pituitary function in nine patients that were in shock after envenomation by Russell's viper and another 24 individuals who had been severely envenomed two weeks to 24 years prior to the study. Three out of the nine patients had hypoglycemia and inappropriately low serum cortisol, plasma growth hormone, and plasma prolactin concentrations. Four who died showed pituitary hemorrhage and one had adrenal hemorrhage. Of the 24 who had apparently recovered from bites, seven had clinical symptoms of hypopituitarism and no response in plasma growth hormone or prolactin concentrations to symptom-producing insulin-induced hypoglycemia. Four men with symptoms showed low serum testosterone concentrations; serum thyroxin was also low in these men but not in two women with menstrual disturbances and impaired insulin responses. Of the 17 individuals without clinical evidence of endocrine disease, and four had pituitary hormonal abnormalities.

In 2011, Antonypillai and colleagues found people envenomed by Russell’s vipers suffer coagulopathy, bleeding, shock, neurotoxicity, acute kidney injury and local tissue damage leading to severe morbidity and mortality; and report the unusual complication of hypopituitarism. They described the first case of hypopituitarism following Russell’s viper bite in Sri Lanka. A 49-year-old man bitten and seriously envenomed by D. russelii in 2005 was treated with antivenom, recovered from the acute effects but remained unwell. Three years later hypopituitarism, with deficiencies of gonadal, steroid and thyroid axes was diagnosed and he showed marked improvement after replacement of anterior pituitary hormones. The authors attributed the hypopituitarism to Daboiai envenomation. Russell’s viper venom is known to cause acute and chronic hypopituitarism and diabetes insipidus, possibly through deposition of fibrin microthrombi and hemorrhage in the pituitary gland that result from the action of procoagulant enzymes and haemorrhagins in the venom. Forty nine cases of hypopituitarism following Russell’s viper bite have been described in the literature. More than 85% of these patients suffered acute kidney injury immediately after the bite, but steroid replacement in acute hypopituitarism is lifesaving.

Although the pituitary gland regulates puberty, it continues to function throughout a person's life and damage can result in failure of the gland to produce the needed hormones. Envenomation by Russell's Vipers often result in significant damage to the gland and hypopituitarism or Sheehan's Syndrome, as suggested by these two studies. Both conditions have symptoms, such as a constant feeling of cold and an unusual amount of fatigue, but what distinguishes them is a loss sex drive, fertility, body hair, and muscle mass (especially pubic hair), while women lose their body shape as they lose weight, and some may lose cognitive skills as the condition progresses.

Citations
Antonypillai CN., Wass, JAH., Warrell, DA, and Rajaratnam, HN. 2011. Hypopituitarism following envenoming by Russell’s Vipers (Daboia siamensis and D. russelii) resembling Sheehan’s syndrome: first case report from Sri Lanka, a review of the literature and recommendations for endocrine management. Oxford Journal of Medicine, 104: 97-108.

Tun-Pe, Warrell DA., Tin Nu, S. Phillips, RE., Moore, RA. 1987. Acute and chronic pituitary failure resembling Sheehan's syndrome following bites by Russell's Vipers in Burma. The Lancet 330: 763-767.

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