Acetonuria

Acetonuria, excretion of acetone with urine. Acetone in very small amounts (about 0.01 g per day) is usually found in urine. Of food substances, the most important source of its formation are fats. Oxidation of fatty acids first gives beta-oxymethylbutyric acid (CH₄.CH.OH.CH₂.COOH), and then acetoacetic acid (CH₃.CO.CH₂.COOH). Acetoacetic acid in the body can be further broken down to CO₂ and H₂O (the pathway of decomposition in detail is unknown); when it is formed in abundance, it is excreted with urine, and also, partly by splitting off CO₂, it converts to acetone: CH₃.CO.CH₂.COOH → CH₃.CO.CH₃ + CO₂. Acetone, in turn, is partly burned, and partly is excreted from the body through the kidneys and, mainly, through the lungs. Proteins can also give rise to acetone, since aromatic amino acids during their decomposition pass through the stage of the corresponding keto acid. The utilization of carbohydrates leads to a decrease in acetone formation, and conversely, in cases where for some reason carbohydrates are not utilized in the body, there is an increased formation of ketone bodies. In the words of Naunyn, "acetone burns in the fire of carbohydrates". A. is observed during starvation, with a deficiency of carbohydrates in the diet, and in diabetes, in which A. has prognostic significance and serves as an indicator of the severity of the case.