Which condition is associated with a mousy odor in urine?

The condition associated with a mousy odor in urine is phenylketonuria (PKU). This genetic disorder results from a deficiency in the enzyme phenylalanine hydroxylase, which is responsible for breaking down phenylalanine, an amino acid found in many protein-containing foods. When this enzyme is absent or dysfunctional, phenylalanine accumulates in the body, leading to various metabolic disturbances.

The distinct mousy smell is attributed to the accumulation of phenylalanine and its metabolites. This characteristic odor can often be an important clinical indicator in diagnosing PKU, especially in newborn screening programs.

In contrast, diabetes mellitus is typically associated with a sweet or fruity odor due to the presence of ketones. Maple syrup urine disease has a sweet, burnt sugar-like smell due to the accumulation of certain amino acids. Isovaleric acidemia exhibits a distinctive sweaty or cheesy odor due to the buildup of isovaleryl-CoA. Each of these conditions has its own unique metabolic pathway and corresponding smell, which can aid in their identification.