INCREASED PLASMA CALCITONIN LEVELS IN SYSTEMIC MAST-CELL DISEASE

Aspirin therapy for patients with systemic mast cell disease (SMCD) de creases the production of prostaglandin D-2, which is thought to be a major mediator of flushing. Paradoxically, in 5 to 10% of patients wit h SMCD, administration of aspirin causes massive mediator release and an anaphylactoid reaction. We attempted aspirin desensitization in a 3 4-year-old man with SMCD (confirmed by bone marrow biopsy) who was inc apacitated by severe flushing episodes and hypotension. His baseline m ediator levels of plasma calcitonin, urinary histamine, and urinary N- methyl-imidazoleacetic acid were abnormal. Pentagastrin stimulation in creased the plasma level of calcitonin from 47 pg/mL to 130 pg/mL (nor mal, less than or equal to 110) at 5 minutes. Oral aspirin desensitiza tion was begun; however, after a cumulative dose of 620 mg, an anaphyl actoid reaction ensued in conjunction with hypotension, abdominal cram ping, and flushing. Coincidentally, 1 hour after the episode, the plas ma calcitonin level increased from 37 pg/mL to 540 pg/mL, and the seru m tryptase level increased from 1 ng/mL to 3.9 ng/mL. Six hours after the episode, the urine level of histamine increased from 90 mu g/g cre atinine to 337 mu g/g creatinine, and the urinary N-methylimidazoleace tic acid increased from 32 mg/ 24 h to 81 mg/24 h. Hence, the patient had increased basal levels of plasma calcitonin that increased substan tially during aspirin desensitization and increased to above the upper limit of normal during pentagastrin stimulation. Human mast cells may be capable of producing calcitonin or causing secretion of calcitonin in response to skeletal changes.