Tuesday, August 29, 2017

Consult Rounds: Tamoxifen induced hypercalcemia

A forgotten cause of hypercalcemia we need to remember is the drug- tamoxifen

This chemotherapy agent used in breast cancer has had a track record of causing hypercalcemia.
It was first described in 1980s.  In that large study, 470 patients with metastatic breast cancer treated with tamoxifen, ten patients (2.3%) developed hypercalcemia. All patients with hypercalcemia had osteolytic or mixed lytic and blastic bone metastases. Hypercalcemia developed after a median period of seven days (range 4-11 days) of tamoxifen administration. Hypercalcemia was treated with conventional measures and serum calcium levels normalized in nine patients, either with a brief interruption of tamoxifen therapy or in spite of continued treatment. Four patients experienced partial remissions with continued tamoxifen therapy. These results indicate that hypercalcemia is a potentially serious complication of tamoxifen therapy but is generally short-lived, and can be controlled with supportive measures, thus allowing continued tamoxifen administration.

Other published reports are

One recent study looked at a large series of breast cancer patients who were hypercalcemic post tamoxifen- happened within 9 days of start and peaked at a level of 13. All patients also had bone lesions as well.  Gallium nitrate was used to reverse the abnormality while keeping tamoxifen on.


No mention of this in any renal literature. Unclear mechanism of this entity. 

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