Infections in Endocrinology: Tuberculosis

Mycobacterium tuberculosis, the etiological agent of tuberculosis (TB), is responsible for the largest number of deaths worldwide caused by a single organism. Over 25% of the world population is infected with M. tuberculosis, though active infections account only for a small percentage. Though some degree of endocrine dysfunction is invariable in all patients with TB, clinically significant endocrinopathy other than glucose intolerance is rare. This chapter reviews endocrine dysfunction and endocrinopathies associated with TB infection related to the adrenal, thyroid and pituitary glands. Additionally, functional derangement of sodium and calcium homeostasis is also covered. Adrenal involvement can be found in up to 6% of patients with active TB, however isolated adrenal involvement is seen only in a fourth of these. The most common clinical manifestation is Addison’s disease (AD). Clinical manifestations of AD appear only after 90% of the adrenal cortices have been compromised. Thyroid tuberculosis (TTB) is very rare, even in countries with a high prevalence of TB. TB has been seen to involve the thyroid in 0.1 to 1% of patients. Primary pituitary TB (in the absence of systemic involvement and/or constitutional symptoms) is extremely rare, and secondary pituitary TB is more commonly encountered in clinical practice. Pituitary TB should be considered in the differential of a suprasellar mass especially in developing countries, as the condition is potentially curable with treatment. Hyponatremia has been commonly seen in patients admitted to the hospital with TB. The commonest cause of hyponatremia is the syndrome of inappropriate antidiuresis (SIAD). Other causes include untreated primary or secondary adrenal insufficiency, volume depletion, hyponatremia associated with volume excess and hypoalbuminemia and rare cases of cerebral salt wasting seen with tuberculous meningitis. The prevalence of hypercalcemia in patients with TB has ranged from 2-51% in various studies. The primary determinant in the development of hypercalcemia among patients with TB appears to be their Vitamin D status and nutritional calcium intake. For complete coverage of all related areas of Endocrinology, please visit our on-line FREE web-text, WWW.ENDOTEXT.ORG.