This article discusses the reference values for basal serum tryptase (BST), which is released by mast cells and is used as a diagnostic marker for certain conditions. The current reference value for BST is controversial, with studies showing that most people have BST values lower than the defined threshold. The article presents data from multiple laboratories, showing that the distribution of BST in healthy donors is not Gaussian and can be explained by two populations: "low-producers" with BST values below 8 μg/L and "high-producers" with values above 8 μg/L. The study also suggests that a small minority of healthy donors may have a defect in basal tryptase production that needs further investigation. [Extracted from the article]