Serum baseline tryptase levels across chronic kidney disease stages: A retrospective report

Chronic kidney disease (CKD) has been associated with elevated serum baseline tryptase (sBT) levels, which may exceed the standard reference value of less than 11.5 ng/mL as kidney function declines.

This study aimed to characterize sBT levels across different CKD stages in a United States-based cohort.

We conducted a retrospective chart review of consecutive nephrology outpatients across the Mayo Clinic enterprise from January 2020 to July 2025. Patients with a confirmed CKD diagnosis (International Classification of Diseases, Revision 10, codes N18.1-N18.5) and an sBT level measured within 40 days of estimation of glomerular filtration rate were included. CKD stages were defined by estimated glomerular filtration rate as follows (mL per minute/1.73 m²): stage 1, greater than or equal to 90; stage 2, 60-89; stage 3a, 45-59; stage 3b, 30-44; stage 4, 15-29; and stage 5, less than 15. Those with conditions known to elevate sBT level (ie, systemic mastocytosis, hereditary alpha-tryptasemia, and renal transplant) were excluded. The Kruskal-Wallis test with Bonferroni adjustment was used for analysis.

A total of 96 patients met the inclusion criteria. The median sBT levels (ng/mL) by CKD stage were as follows: stage 1, 3.3 (interquartile range [IQR] = 0.0); stage 2, 5.6 (IQR = 3.9); stage 3a, 7.6 (IQR = 4.35); stage 3b, 6.3 (IQR = 2.8); and stage 4, 11.1 (IQR = 4.35). A statistically significant difference was observed in the distribution of sBT levels across CKD stages (χ² = 11.6 [P = .02]).

A statistically significant association between CKD stage and serum baseline tryptase level has been observed, suggesting that declining kidney function may influence circulating tryptase concentrations. This finding highlights the importance of accounting for renal function when interpreting elevated sBT values.