Quantitation of urinary metabolites of
histamine,
prostaglandin D2, and
leukotriene E4 can fill the gap in our current efforts to improve diagnosis and management of symptomatic patients with
systemic mastocytosis, and/or
mast cell activation syndrome, In addition, patients symptomatic due to mast cell activation but who do not meet all the criteria for
mast cell activation syndrome can have elevated baseline mediator metabolites. Serum
tryptase levels have been the workhorse in diagnosing these disorders, but it has several drawbacks including the need to obtain acute and baseline samples, which require 2 visits to health care facilities and 2 venipunctures. Recently, increased baseline
tryptase level has been reported in
hereditary alpha tryptasemia, complicating diagnostic possibilities of an increased baseline
tryptase level. Furthermore, no treatment can specifically be targeted at
tryptase itself. In contrast, the finding of 1 or more elevated urinary levels of
histamine,
prostaglandin D2, and/or
leukotriene E4 metabolites (1) greatly narrows diagnostic possibilities for causes of symptoms; (2) informs the practitioner what specific metabolic pathways are involved; and (3) targets the treatment in a specific, direct fashion. As a bonus, baseline spot/random urine samples can be obtained by the patients themselves and repeated at exactly the correct time when symptoms occur.