Today we discussed a classic case of Multiple Myeloma with hypercalcemia, renal failure, anemia, and bone pain secondary to lytic bone lesions... these features make up the mnemonic CRAB: hyperCalcemia, Renal failure, Anemia, Bone pain.
Here is a link to a previous Horses & Zebras blog summarizing the Clinical Features of Multiple Myeloma, as well as some links to articles reviewing investigation and management of hypercalcemia and current management options for multiple myeloma.
Management of hypercalcemia +/- acute renal failure is often the primary problem that needs to be managed on admission to hospital. Hypercalcemia can be considered to be mild (2.6 - 2.9 mmol/L), moderate (3.0 - 3.4 mmol/L), and severe (greater than 3.5 mmol/L); however, there are no official cut-off points for hypercalcemia. As we discussed this morning, ~40% of calcium is bound to albumin and thus low albumin states will lower the measured calcium. This can be corrected roughly by adding 0.2 mmol/L to a calcium measurement for every drop in albumin of ~10.
Treatment of Hypercalcemia
1. First line treatment for hypercalcemia is fluid resuscitation, as the majority of patients will be volume contracted. Rapid, aggressive resuscitation is the goal, monitoring for any potential volume overload/heart failure in susceptible patients.
2. Administration of an IV bisphosphonate is also considered appropriate in severe hypercalcemia. Pamidronate (60 - 90 mg) is the usual choice, given once over 2-4 hours, and most often normalizing calcium within 5-7 days.
3. For more immediate calcium-lowering calcitonin can be considered; however, it is not uncommon for patients to develop tachyphylaxis and thus its use is limited.
4. Alternatively, and often more effective in the setting of lymphoma or multiple myeloma induced hypercalcemia, glucocorticoids such as prednisone (1 mg/kg daily) can be considered.
5. Management of hypercalcemia always includes investigation into the underlying cause, and treatment of such problem otherwise the hypercalcemia will recur.