Long-term follow-up of histamine turnover in mastocytosis.

To study the long-term histamine turnover in patients with mastocytosis, the urinary excretion of the main histamine metabolite tele-methylimidazoleacetic acid was measured. Eighteen patients, 10 with urticaria pigmentosa and 8 with systemic mastocytosis, were followed for several years (mean 4.2 years). Younger individuals (less than 30 years) had initially normal excretion or tended to normalize their excretion during follow-up, while older patients (greater than 30 years) often had systemic manifestations and higher excretion values, which increased in some cases during the observation period.