A 57-year-old woman with a 4-year history of metastatic breast cancer was found by her family to be very lethargic and sleepy. She had previously been acting strangely and complaining of nausea, constipation, abdominal pain, and constant thirst.
An ECG shows:
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What is the most important initial step in the emergency treatment of this patient’s likely acute problem?
- Mithramycin 25 micrograms/kg every 4 to 5 days
- Calcitonin 4-8 IU/kg body weight
- Saline fluid bolus
- Prednisone 60-80 mg/day
The correct answer is:
Saline fluid bolus
Educational Objective:
Discuss recognition and management of hypercalcemia.
Key Point:
First-line treatment for malignancy-associated hypercalcemia is intravenous fluid.
Explanation:
The above ECG shows marked QT shortening most consistent with significant hypercalcemia. Hypercalcemia interferes with resorption of water and sodium by the kidney, leading to severe hypovolemia that results in hypopersion and further limits the kidneys’ ability to eliminate calcium. This creates a fatal positive feedback loop of increasing hypercalcemia and hypovolemia.
Hydration breaks this cycle and is the first step, generally by administration of intravenous fluid at rates of at least 200 to 500 mL/hr.
If urine output does not improve due to concomitant cardiac or renal failure, the resulting overhydration should be treated with a combination of loop diuretics (furosemide, e.g. 40-60 mg IV), dialysis, and positive-pressure ventilation.
Hypercalcemic patients with baseline oliguria or anuria will likely require dialysis.
Historically, loop diuretics were recommended together with the IV hydration even in the absence of overhydration because loop diuretics increase calcium excretion by the kidneys. However, this approach led to high complication rates and minimal additional excretion of calcium. Therefore loop diuretics are now only recommended for volume management, no longer for forced calcium excretion in otherwise euvolemic patients.
Thiazide diuretics enhance distal tubule calcium resorption and should be avoided in hypercalcemic patients.
Mithramycin, calcitonin, and also prednisone are all long-term agents with a slow onset for treating hypercalcemia. They are therefore NOT the first step. However, it may be reasonable to start them emergently (especially calcitonin) AFTER fuid resuscitation in order to initiate the process of long term stabilization.
Intravenous phosphates are not consistently recommended (varies by author) because of their serious complications.
References:
McCurdy MT, Wacker DW. Selected Oncologic Emergencies (chapter 115). In Rosen’s Emergency Medicine, 9th ed.: 2018
This question appears in Med-Challenger Emergency Medicine Review with CME
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