MEDizzy - A 55-year-old female sees her family doctor with a red

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Endocrine System

A 55-year-old female sees her family doctor with a red blistering rash around the mouth. She reports weight loss but says it is because “eating isn’t fun anymore.” Her vital signs are normal. Her serum laboratory results are as follows. Normal reference values are in parentheses: Total calcium 9.2 (8.5–10.5) mg/dL Potassium 4.2 (3.5–5.0) mEq/L Sodium 138 (135–145) mEq/L Glucose (fasting) 162 (65–110) mg/dL Albumin 3.8 (3.5–5.5) g/dL RBC 3.18 (3.9–5.6) × 1012/L Hct 35 (36–48) % Hgb 11.2 (11.5–15.5) g/dL MCV 85 (80–95) fL MCH 29 (27–34) pg A hormone-producing tumor is suspected. Which of the following cell types is most likely hypertrophied?

ExplanationPancreatic islet α cells produce glucagon. Hyperglucagonemia causes hyperglycemia and diabetes mellitus type 2. Weight loss is likely due to glucagon stimulating lipolysis and proteinolysis. Anemia (normocytic normochromic) is likely due to glucagon’s catabolic action on the bone marrow. The rash, called necrolytic migratory erythema, is a common sign of a glucagonoma, but this knowledge is not necessary to answer the question. (B) Pancreatic β cells produce insulin. Hyperinsulinemia causes hypoglycemia (not hyperglycemia). (C) Thyroidal parafollicular cells produce calcitonin. Excess calcitonin causes hypocalcemia (not normal serum calcium). (D) Adrenal zona fasciculata cells produce cortisol. Hypercortisolism produces signs of Cushing’s syndrome, among them hypernatremia and hypokalemia (patient’s values are normal).