Tryptase is not cleared by the kidneys into the urine.

BACKGROUND Patients with chronic kidney disease have been reported to have increased concentrations of blood tryptase. Detection of tryptase in the urine of healthy subjects has been reported. OBJECTIVE The objective is to determine whether tryptase is indeed cleared by the kidneys. METHODS Blood and urine collections were performed in healthy and systemic mastocytosis subjects. Total and mature tryptase concentrations in blood and total tryptase concentrations in urine were determined. RESULTS Total tryptase levels in urine were below the limit of detection in both healthy subjects and those with systemic mastocytosis, even after concentrating the urine 10-fold. Thus, both mature and protryptase levels in urine are <0.2 ng/ml. CONCLUSION Tryptase is not cleared by the kidneys into the urine.