A family brings their 82-year-old grandmother to the emergency room stating that they cannot care for her anymore. They tell you, “She has just been getting sicker and sicker.” Now she stays in bed and won’t eat because of stomach pain. She is too weak to go to the bathroom on her own. Her symptoms have been worsening over the past year, but she has refused to see a doctor. The patient denies symptoms of depression. Blood pressure is 90/54 with the patient supine; it drops to 76/40 when she stands. Heart and lungs are normal. Skin examination reveals a bronze coloring to the elbows and palmar creases. What laboratory abnormality would you expect to find in this patient?
A. Low-serum Ca+This patient’s presentation suggests adrenal insufficiency (Addison disease). Hyponatremia is caused by loss of sodium in the urine (aldosterone deficiency) and free-water retention. Sodium loss causes volume depletion and orthostatic hypotension. Hyperkalemia is caused by aldosterone deficiency, impaired glomerular filtration, and acidosis. Ten to twenty percent of patients with adrenal insufficiency will have mild hypercalcemia; hypocalcemia is not expected. Complete blood count can reveal a normocytic anemia, relative lymphocytosis, and a moderate eosinophilia. Microcytic anemia would suggest an iron disorder or thalassemia. The hyperpigmentation results from the release of pro-opiomelanocortin which has melanocyte-stimulating activity. Hyperpigmentation is not seen if pituitary dysfunction is causing the adrenal insufficiency (ie, in secondary hypoadrenalism).