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Urinary N‐methylhistamine as an indicator of bone marrow involvement in mastocytosis
Author(s) -
Oranje A. P.,
Riezebos P.,
Van Toorenenbergen A. W.,
Mulder P. G. H.,
Heide R.,
Tank B.
Publication year - 2002
Publication title -
clinical and experimental dermatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.587
H-Index - 78
eISSN - 1365-2230
pISSN - 0307-6938
DOI - 10.1046/j.1365-2230.2002.01072.x
Subject(s) - bone marrow , biopsy , systemic mastocytosis , mast cell , medicine , creatinine , urinary system , skin biopsy , pathology , cutaneous mastocytosis , gastroenterology , immunology
Summary Thirty‐seven patients with mastocytosis and unexplained elevated levels of urinary N‐methylhistamine who were undergoing bone marrow biopsy were studied with respect to the diagnosis of mastocytosis and the manifestations of the disease. These patients were from a group of 66 patients from whom a bone marrow biopsy was obtained and urinary N‐methylhistamine levels were measured in the period 1990–1998 . In seven (19%) of the 37 patients, mastocytosis was limited to the skin. Five (14%) of the 37 patients showed accumulation of mast cells in the bone marrow without characteristic skin lesions, whereas seven (19%) of the 37 patients showed increased numbers of mast cells both in the skin and the bone marrow. Eighteen (49%) of the 37 patients with elevated N‐methylhistamine did not have mast cell accumulation in either the skin or the bone marrow biopsy. The median level of N‐methylhistamine in the urine of patients with mastocytosis limited to the skin was 245 µmol/mol creatinine. The average level of N‐methylhistamine was 509 µmol/mol creatinine in patients with mast cell accumulation in the bone marrow and cutaneous mastocytosis. There was a significant difference in the levels of N‐methylhistamine in patients with mast cell accumulation in the bone marrow biopsy compared with those without. The likelihood of mastocytosis with mast cell accumulation in the bone marrow biopsy at a given level of N‐methylhistamine was calculated. It was established that an N‐methylhistamine level of 297 µmol/mol creatinine or higher may be considered as a threshold indicator for obtaining a bone marrow biopsy in patients suspected of mastocytosis with mast cell accumulation in the bone marrow. For practical purposes, we propose to consider the cut‐off level of ≈ 300 µmol/mol N‐methylhistamine creatinine for this assay.