A 50-year-old man comes to the office due to lightheadedness and fatigue for the last several weeks. Over the last few days, he has become lightheaded when standing up. He has also experienced subjective fevers and a daily cough for the past 3 months and has lost 8 kg (17.6 lb) during that time. The patient has no known medical history. He does not use tobacco, alcohol, or illicit drugs and takes no medications. He immigrated from Southeast Asia 25 years ago and occasionally makes trips back there to visit family. Temperature is 38 C (100.4 F), blood pressure is 96/62 mm Hg, pulse is 98/min and regular, and respirations are 14/min. Oxygen saturation is 94% on room air. On physical examination, the neck veins are flat. Laboratory results are as follows: Chest x-ray reveals patchy airspace disease in the left upper lung lobe as well as mediastinal lymphadenopathy. Which of the following is most likely responsible for this patient's lightheadedness?

Question

A 50-year-old man comes to the office due to lightheadedness and fatigue for the last several weeks.  Over the last few days, he has become lightheaded when standing up.  He has also experienced subjective fevers and a daily cough for the past 3 months and has lost 8 kg (17.6 lb) during that time.  The patient has no known medical history.  He does not use tobacco, alcohol, or illicit drugs and takes no medications.  He immigrated from Southeast Asia 25 years ago and occasionally makes trips back there to visit family.  Temperature is 38 C (100.4 F), blood pressure is 96/62 mm Hg, pulse is 98/min and regular, and respirations are 14/min.  Oxygen saturation is 94% on room air.  On physical examination, the neck veins are flat.  Laboratory results are as follows:  Chest x-ray reveals patchy airspace disease in the left upper lung lobe as well as mediastinal lymphadenopathy.  Which of the following is most likely responsible for this patient's lightheadedness?

Quizplus · Accepted Answer

This patient has multiple findings consistent with primary adrenal insufficiency (PAI) (Addison disease). Although autoimmune adrenalitis is the most common etiology, disseminated chronic infection (eg, tuberculosis, histoplasmosis) can also cause the disorder. This patient's evidence of PAI combined with fevers, pulmonary airspace disease (eg, daily cough) with lymphadenopathy, and prior residence in a tuberculosis-endemic region (>30% of global tuberculosis burden in Southeast Asia) suggests miliary tuberculosis. PAI involves the destruction of all 3 layers of the adrenal cortex. Lightheadedness and orthostasis (as seen in this patient) are due to reduced aldosterone causing renal sodium wasting (eg, weight loss, hypovolemia), with accompanying hyponatremia (antidiuretic hormone stimulation) and hyperkalemia (renal potassium retention). Reduced cortisol production contributes to hypotension and causes hypoglycemia; it can also cause peripheral eosinophilia (nonspecific finding sometimes seen with adrenal insufficiency) as cortisol normally facilitates eosinophil migration from the bloodstream into the tissues. 3 layers Tuberculous adrenalitis (due to extrapulmonary hematogeneous spread) is the second most common cause of adrenal insufficiency worldwide. Antituberculous therapy rarely improves adrenal function, as the infection often causes irreversible destruction. (Choice A) Sarcoidosis classically presents with pulmonary manifestations and hilar and/or mediastinal lymphadenopathy. It may cause PAI due to infiltration of the adrenal cortex; however, it more commonly causes secondary adrenal insufficiency due to infiltration of the hypothalamus with disruption of the hypothalamic-pituitary axis (HPA). Secondary adrenal insufficiency involves decreased production of ACTH and, because aldosterone production is primarily driven by angiotensin II rather than ACTH, can be differentiated from PAI by an absence of aldosterone deficiency and its associated manifestations (eg, hypovolemia, hyperkalemia). secondary (Choice C) Tuberculosis can involve the pericardium, leading to pericardial effusion and possibly cardiac tamponade. Although this could cause hypotension and orthostasis, it would not explain hyperkalemia and hypoglycemia. (Choice D) Small cell lung cancer is associated with paraneoplastic syndromes, including ectopic ACTH production; however, this would cause manifestations of hypercortisolism (eg, weight gain, hyperglycemia) rather than PAI. (Choice E) Strongyloidiasis is a parasitic infection that is endemic to rural tropical regions throughout the world. Chronic infection typically causes respiratory (eg, cough, dyspnea) and gastrointestinal (eg, nausea, vomiting, diarrhea) symptoms. Eosinophilia is common but neither adrenal gland nor HPA involvement is expected; therefore, it would not explain other manifestations of adrenal insufficiency. Educational objective: Primary adrenal insufficiency (PAI) is a potential complication of miliary tuberculosis. Signs and symptoms of aldosterone deficiency (eg, hypovolemia, hyperkalemia) are present in PAI and can help differentiate PAI from secondary adrenal insufficiency. References: Addison's disease due to adrenal tuberculosis: contrast-enhanced CT features and clinical duration correlation. (http://www.ncbi.nlm.nih.gov/pubmed/17182208)

A 50-Year-Old Man Comes to the Office Due to Lightheadedness