The presence of the odor of acetone from the mouth in a child or adolescent is indicative of acetonemia (hyperacetonemia) - an excess of ketones in the blood. Oxidizing, they lower the pH of the blood, that is, increase its acidity and lead to acidosis.
The pathogenesis of hyperacetonemia and ketoacidosis in diabetes mellitus is caused by a lack of insulin and hypoglycemia, which leads to increased lipolysis - the cleavage of triglycerides into fatty acids and transport them to the liver. In hepatocytes they are oxidized with the formation of acetyl-coenzyme A (acetyl-CoA), and from its surplus ketones are formed - acetoacetic acid and β-hydroxybutyrate. The liver does not cope with the treatment of so many ketones, and their level in the blood increases. Further, acetoacetic acid is decarboxylated to dimethyl ketone (acetone), which is excreted from the body through the lungs, sweat glands and kidneys (with urine). With an increased amount of this substance in the exhaled air, there is a smell of acetone from the mouth.
Cell and membrane enzymes (CoA transferase, acyl-CoA dehydrogenase, β-thioketolase, carnitine, carnitine acyltransferase, etc.) are required to oxidize fatty acids, and their genetically determined deficiency in congenital syndromes is the leading cause of ketone metabolism disorders. In some cases, the mutations of the gene of the hepatic enzyme phosphorylase located on the X chromosome are responsible, leading to a deficiency or a decrease in activity. In children aged one to five years, the presence of a mutant gene is manifested as a smell of acetone from the mouth, as well as growth retardation and hepatomegaly (increase in the liver). Over time, liver size normalizes, the child in most cases begins to catch up with peers on growth, but the liver can form fibrous septa and there are signs of inflammation.
The development of ketoacidosis in cases of increased production of thyroid hormones in hyperthyroidism is explained by a violation of the metabolism of fats and proteins, since thyroid hormones (thyroxine, triiodothyronine, etc.) not only accelerate the general metabolism (including protein digestion), but also can form resistance to insulin. Studies have revealed a strong genetic predisposition to autoimmune pathologies of the thyroid gland and type 1 diabetes.
And with an excess of fat in the food consumed by children, the transformation of fatty acids into fatty acid triglycerides in the fat cells is hampered, why some of them appear in mitochondria of liver cells where they are oxidized with the formation of ketones.