title: Urinary N-methylhistamine as an indicator of bone marrow involvement in mastocytosis.
abstract: 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 micro mol/mol creatinine. The average level of N-methylhistamine was 509 micro mol/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 micro mol/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 approximately 300 micro mol/mol N-methylhistamine creatinine for this assay.
authors.affiliation: Departments of Dermatology, University Hospital Rotterdam, Dijkzigt and Erasmus University, Rotterdam, the Netherlands. aoranje@inter.NL.net
authors.forename: A P
authors.initials: AP
authors.lastname: Oranje
authors.forename: P G H
authors.initials: PG
authors.lastname: Mulder
authors.forename: R
authors.initials: R
authors.lastname: Heide
authors.forename: B
authors.initials: B
authors.lastname: Tank
authors.forename: P
authors.initials: P
authors.lastname: Riezebos
authors.forename: A W
authors.initials: AW
authors.lastname: van Toorenenbergen
mesh_terms: D015415:Biomarkers / Q000652:urine; D001706:Biopsy; D001853:Bone Marrow / Q000473:pathology*; D006801:Humans; D008407:Mast Cells / Q000473:pathology; D008415:Mastocytosis / Q000473:pathology* / Q000652:urine; D008761:Methylhistamines / Q000652:urine*; D012372:ROC Curve; D012680:Sensitivity and Specificity; D012867:Skin / Q000473:pathology
chemical_list: D015415:Biomarkers; D008761:Methylhistamines; C048140:N-methylhistamine