Hypercalcemic crisis associated with the hypereosinophilic syndrome.

A patient with the idiopathic hyperosinophilic syndrome had severe, life-threatening hypercalcemia, a previously unreported complication of this unusual disease. Postmortem examination revelaed multiorgan eosinophilic infiltration and diffuse metastatic calcifications, but it did not disclose a definitive cause for the persistent hypercalcemia. It is concluded that the marked proliferation of eosinophils was the probable etiologic factor. Proposed mechanisms for this complication include (1) the destruction of bone by an expanding eosinophilic cell mass with subsequent calcium mobilization and (2) the production of a hypercalcemic humoral substance, possibly by the patient's eosinophils or as a consequence of their presence.