Thanks to John for presenting the case of a middle-aged woman with metastatic renal cell carcinoma who presented with subacute diffuse weakness and constipation, found to have symptomatic hypercalcemia, treated with IV fluids and zoledronic acid.

Clinical Pearls

• A third of patients with malignancy develop hypercalcemia in their disease course.  Hypercalcemia of malignancy is associated with very poor prognosis (~50% 30 day mortality).
• Constipation plus polyuria is the most specific symptom combination for hypercalcemia
• Denosumab is superior to zoledronic acid in treating hypercalcemia of malignancy and is safe to use in renal failure.
• One way to quickly determine the etiology of hypercalcemia from your chemistry panel is to look at the chloride to phosphate ratio.  A ratio > 33 is highly suggestive of a PTH or PTHrP mediated process.

Hypercalcemia ddx:

** Primary hyperPTH is the most common cause of hypercalcemia in the outpatient setting.  Malignancy is the most common cause of hypercalcemia in the inpatient setting.

Treatment of hypercalcemia:

Ca <12

• No treatment if asymptomatic
• Avoid exacerbating factors

Ca 12-14

• If chronic/asymptomatic ⇒ same tx as Ca <12
• If acute/symptomatic ⇒ same tx as Ca 14-18

Ca 14-18

• IVF – lots!
• Lasix only if concurrent renal/heart failure
• Calcitonin
• Bisphosphonate (zoledronic acid >>pamidronate if malignancy. Denosumab if refractory to ZA or severe renal impairment)

Ca >18

• Above PLUS
• Hemodialysis