Ketoacidosis

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Ketoacidosis
Classification and external resources
DiseasesDB 29670
eMedicine med/102 

Ketoacidosis is a type of metabolic acidosis which is caused by high concentrations of ketone bodies, formed by the deamination of amino acids, and the breakdown of fatty acids. The two common ketones produced in humans are acetoacetic acid and β-hydroxybutyrate. This is most common in untreated type 1 diabetes mellitus, when the liver breaks down fat and proteins in response to a perceived need for respiratory substrate. It can also occur with people undergoing hunger strikes, fasting over 3 days, or people starving to death as the body is forced to break down fat for sustenance due to their lack of outside nutrition. Ketoacidosis can be smelled on a person's breath. This is due to acetone, a direct byproduct of the spontaneous decomposition of acetoacetic acid. It is often described as smelling like fruit or nail polish remover. [1]

Ketoacidosis should not be confused with ketosis, which is one of the body's normal processes for the metabolism of body fat. In ketoacidosis, the accumulation of keto acids is so severe that the pH of the blood is substantially decreased.

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[edit] Pathophysiology

Ketoacidosis occurs when cells do not have sufficient glucose to meet their metabolic demands. Instead, ketone bodies are produced for energy via the metabolism of fatty acids.

Acidity results from the dissociation of the H+ ion at physiological pH of metabolic ketone bodies such as acetoacetate, and β-hydroxybutyrate.

[edit] Etiology

Two common causes include diabetic and alcoholic ketoacidosis.

In diabetic patients, ketoacidosis is usually accompanied by insulin deficiency, hyperglycemia, and dehydration. Since insulin is required to absorb glucose from the blood, its deficiency results in an energy crisis, fatty acid metabolism, and production of ketone bodies. Hyperglycemia results in glucose overloading the nephron and spilling into the urine. Dehydration results following the osmotic movement of water into urine, exacerbating the acidosis.

In alcoholic ketoacidosis, alcohol causes dehydration and blocks the first step of gluconeogenesis. The body is unable to synthesize enough glucose to meet its needs, thus creating an energy crisis resulting in fatty acid metabolism, and ketone body formation.

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