A 34-year-old woman comes to the office due to generalized weakness and extreme fatigue. She has had a sore throat, rhinorrhea, and cough productive of a small amount of clear sputum for the past 3 days. The patient has also experienced intermittent anorexia, nausea, and weight loss over the last several months. She has a history of primary hypothyroidism and takes 100 µg of levothyroxine daily. The patient does not use tobacco, alcohol, or illicit drugs.
Temperature is 37.6 C (99.8 F), blood pressure is 90/60 mm Hg, and pulse is 110/min. Cardiac, lung, and abdominal examinations are unremarkable.
Laboratory results are as follows:
Which of the following is the most likely cause of this patient's current symptoms?

Question

A 34-year-old woman comes to the office due to generalized weakness and extreme fatigue.  She has had a sore throat, rhinorrhea, and cough productive of a small amount of clear sputum for the past 3 days.  The patient has also experienced intermittent anorexia, nausea, and weight loss over the last several months.  She has a history of primary hypothyroidism and takes 100 µg of levothyroxine daily.  The patient does not use tobacco, alcohol, or illicit drugs.
Temperature is 37.6 C (99.8 F), blood pressure is 90/60 mm Hg, and pulse is 110/min.  Cardiac, lung, and abdominal examinations are unremarkable.
Laboratory results are as follows:
 Which of the following is the most likely cause of this patient's current symptoms?

Quizplus · Accepted Answer

11ec193a_97a6_eee8_853d_475b74b7cff2_MD0002_00 This patient's clinical findings of fatigue, hyponatremia, low blood glucose, and hypotension in the setting of an upper respiratory illness are suggestive of primary adrenal insufficiency (PAI [Addison disease]). PAI is most commonly due to autoimmune adrenalitis (>90%) and often occurs in patients with other autoimmune endocrine disorders (eg, hypothyroidism, type 1 diabetes mellitus). The initial symptoms of chronic PAI are often nonspecific and include fatigue and weight loss. However, acute stressors (eg, infection, major surgery) can precipitate adrenal crisis, causing abdominal pain, shock, and altered mental status. Patients with PAI present with multiple electrolyte abnormalities from both mineralocorticoid and glucocorticoid deficiency, including non-anion-gap metabolic acidosis, hyponatremia, hypoglycemia, and hyperkalemia (although elevated potassium occurs only in 40% of patients). Mild hypercalcemia may also be noted; this is thought to be due to hemoconcentration and acute renal failure in the setting of hypovolemia. Increased ACTH secretion leads to skin hyperpigmentation due to concurrent melanocyte-stimulating hormone formation. The initial evaluation should include an 8 AM serum cortisol assay, plasma ACTH level, and ACTH stimulation test (cosyntropin test). Rapid improvement of clinical features is seen with corticosteroid (eg, hydrocortisone) replacement. (Choice A) Acute kidney injury due to acute interstitial nephritis typically presents with rash, fever, eosinophilia, eosinophiluria, and active urine sediment (ie, red and white blood cells and casts). This patient has a bland urinary sediment, and her mildly elevated creatinine is likely related to hypovolemia and decreased renal perfusion in PAI. (Choice C) Patients with Legionella pneumophila pneumonia commonly have hyponatremia initially. Other typical features include fever with relative bradycardia and gastrointestinal distress (eg, vomiting, cramps). However, this patient has a normal pulmonary examination, and her preceding symptoms (anorexia, weight loss) suggest PAI. (Choice D) Excessive thyroid hormone may cause fatigue, weight loss, and tachycardia; however, hyponatremia, hyperkalemia, and low blood glucose are not common in thyrotoxicosis. (Choice E) The syndrome of inappropriate antidiuretic hormone secretion typically presents as euvolemic hyponatremia with concentrated urine. This patient appears hypovolemic, making this diagnosis less likely. Educational objective: Primary adrenal insufficiency (PAI) is usually due to autoimmune adrenalitis and may be seen with other autoimmune endocrine disorders. Typical findings include fatigue, hypotension, hyponatremia, and low blood glucose. PAI can become acutely worse due to acute stressors, leading to adrenal crisis. Initial evaluation includes 8 AM serum cortisol, plasma ACTH, and ACTH stimulation test. Treatment requires corticosteroid replacement. __________ References: Addison disease: early detection and treatment principles. (http://www.ncbi.nlm.nih.gov/pubmed/24695602)

A 34-Year-Old Woman Comes to the Office Due to Generalized