High anion gap metabolic acidosis

High anion gap metabolic acidosis is a form of metabolic acidosis characterized by a high anion gap.

The list of agents that cause high anion gap metabolic acidosis is similar to but broader than the list of agents that cause a serum osmolal gap.

High Anion Gap Metabolic acidosis is caused generally by the body producing too much acid or not producing enough bicarbonate. This is often an increase in lactic acid or ketoacids, or a sign of kidney failure, and more rarely may be caused by ingesting methanol or overdosing on aspirin. The delta ratio is a formula that can be used to assess elevated anion gap metabolic acidosis and to evaluate whether mixed acid base disorder (metabolic acidosis) is present.

Causes
Causes include:

"Mudpiles"
The mnemonic MUDPILES is commonly used to remember the causes of increased anion gap metabolic acidosis.
 * M-Methanol
 * U-Uremia (chronic kidney failure)
 * D-Diabetic ketoacidosis
 * P-Propylene glycol ("P" used to stand for Paraldehyde but this substance is not commonly used today)
 * I-Infection, Iron, Isoniazid, Inborn errors of metabolism
 * L-Lactic acidosis
 * E-Ethylene glycol (Note: Ethanol is sometimes included in this mnemonic as well, although the acidosis caused by ethanol is actually primarily due to the increased production of lactic acid found in such intoxication.)
 * S-Salicylates

Another frequently used mnemonic is KARMEL.
 * K-Ketoacidosis
 * A-aspirin
 * R-Renal failure
 * M-Methanol
 * E-Ethylene glycol
 * L-Lactic acidosis

Another frequently used mnemonic is KUPIN.
 * K-Ketoacidosis (DKA, AKA)
 * U-Uremia
 * P-Production (Lactic acidosis)
 * I-Ingestion (Ethylene glycol, methanol)
 * N- Need to Remember Drugs (aspirin, Metformin)

The mnemonic for the [rare, in comparison] toxins is ACE GIFTs: Aspirin, Cyanide, Ethanolic ketosis, Glycols [ ethylene and propylene ], Isoniazid, Ferrous iron, Toluene. Most of these cause a lactic acidosis.

Other

 * formaldehyde
 * toluene
 * sulfates
 * metformin
 * rhabdomyolysis