A 60-year-old woman is brought to the emergency department by her husband due to confusion. She has been increasingly confused over the last 2 days. The patient also has a 2-week history of excessive urination, heartburn, nausea, vomiting, and fatigue. She has had no associated fever, chills, chest pain, or respiratory symptoms. Medical history is notable for coronary artery disease, hypertension, and gastroesophageal reflux. The patient takes several medications, including an over-the-counter medication for heartburn, but her husband does not recall their names.
Temperature is 37.2 C (99 F), blood pressure is 146/90 mm Hg, pulse is 90/min, and respirations are 16/min. Pulse oximetry is 96% on room air. Mucous membranes are dry. The patient cannot recall 2 of 3 items acutely. The lungs are clear with no cardiac murmurs or gallops. She has no skin rashes.
Laboratory results are as follows:
The patient's serum calcium rapidly improves with an infusion of normal saline.
Which of the following is the most likely diagnosis?

Question

A 60-year-old woman is brought to the emergency department by her husband due to confusion.  She has been increasingly confused over the last 2 days.  The patient also has a 2-week history of excessive urination, heartburn, nausea, vomiting, and fatigue.  She has had no associated fever, chills, chest pain, or respiratory symptoms.  Medical history is notable for coronary artery disease, hypertension, and gastroesophageal reflux.  The patient takes several medications, including an over-the-counter medication for heartburn, but her husband does not recall their names.
Temperature is 37.2 C (99 F), blood pressure is 146/90 mm Hg, pulse is 90/min, and respirations are 16/min.  Pulse oximetry is 96% on room air.  Mucous membranes are dry.  The patient cannot recall 2 of 3 items acutely.  The lungs are clear with no cardiac murmurs or gallops.  She has no skin rashes.
Laboratory results are as follows:
 The patient's serum calcium rapidly improves with an infusion of normal saline.
Which of the following is the most likely diagnosis?

Quizplus · Accepted Answer

11ec193a_9725_14e0_853d_d1b73dd7bc52_MD0002_00 This patient has parathyroid hormone (PTH)-independent hypercalcemia (ie, hypercalcemia with a low or low-normal PTH level). In addition, she has renal insufficiency and alkalosis. Together, this triad is most consistent with milk-alkali syndrome (MAS). MAS is caused by excessive intake of calcium and absorbable alkali, most commonly due to the use of calcium carbonate preparations for osteoporosis or heartburn. The resulting hypercalcemia causes renal vasoconstriction with decreased glomerular blood flow and leads to increased natriuresis, with eventual volume depletion and metabolic alkalosis due to increased renal tubular bicarbonate resorption. Patients also frequently have hypophosphatemia due to the phosphate-binding effect of calcium carbonate. The risk of MAS is increased in patients taking medications that decrease glomerular filtration (eg, ACE inhibitors/angiotensin II receptor blockers, nonsteroidal anti-inflammatory drugs). Manifestations can range from incidental hypercalcemia, to acute symptomatic hypercalcemia, to chronic kidney disease with metastatic calcification. The hypercalcemia in MAS corrects promptly with isotonic saline infusion and (if necessary) furosemide. (Choice A) Granulomatous diseases (eg, sarcoidosis) cause hypercalcemia due to increased production of 1,25-dihydroxyvitamin D and increased intestinal calcium absorption. This patient's 1,25-dihydroxyvitamin D level is at the low end of normal. (Choice B) Malignancy-induced hypercalcemia is possible in this patient but less likely than MAS in light of her history of taking an over-the-counter medication for heartburn (most likely calcium carbonate), coexistent alkalosis, and rapid correction with normal saline. (Choice D) This patient has a suppressed PTH level, which rules out primary hyperparathyroidism. (Choice E) Thiazide diuretics can cause hypercalcemia due to increased renal reabsorption of calcium. Although thiazides can increase the risk for MAS, the hypercalcemia attributable to thiazides is usually very mild and rarely symptomatic. Educational objective: Milk-alkali syndrome is characterized by parathyroid hormone-independent hypercalcemia, renal insufficiency, and metabolic alkalosis. It is usually caused by excessive ingestion of calcium carbonate. The risk is increased in patients taking medications that decrease glomerular filtration. Treatment includes isotonic saline infusion and furosemide. __________ References: Milk-alkali syndrome. (http://www.ncbi.nlm.nih.gov/pubmed/19252114)

A 60-Year-Old Woman Is Brought to the Emergency Department by Her