chemistry

High anion gap metabolic acidosis

High anion gap metabolic acidosis is a chemistry topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand High anion gap metabolic acidosis rather than just read about it. In short: High anion gap metabolic acidosis is a form of metabolic acidosis characterized by a high anion gap (a medical value based on the concentrations of ions in a patient's serum). Metabolic acidosis occurs when the body produces too much acid, or when the kidneys are not removing enough acid from the body.

Key takeaways

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Reference excerpt

High anion gap metabolic acidosis is a form of metabolic acidosis characterized by a high anion gap (a medical value based on the concentrations of ions in a patient's serum). Metabolic acidosis occurs when the body produces too much acid, or when the kidneys are not removing enough acid from the body. Several types of metabolic acidosis occur, grouped by their influence on the anion gap. The anion gap can be increased due to relatively low levels of cations other than sodium and potassium (e.g. calcium or magnesium). An anion gap is usually considered to be high if it is over 12 mEq/L. High anion gap metabolic acidosis is typically caused by acid produced by the body. More rarely, it 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. 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.

Causes

The most common causes of high anion gap metabolic acidosis are ketoacidosis, lactic acidosis, kidney failure, and toxic ingestions. Ketoacidosis can occur as a complication of diabetes mellitus (diabetic ketoacidosis) or as a result of other disorders, such as chronic alcoholism and malnutrition. In these conditions, excessive free fatty acid metabolism results in the production of ketoacids, acetoacetic acid, and beta-hydroxybutyrate. Lactic acidosis results from excess formation and decreased metabolism of lactate, which occurs during states of anaerobic metabolism. It is the most common cause of metabolic acidosis in hospitalized patients. The most serious form occurs during various states of shock, due to episodes of decreased liver perfusion. Kidney failure results in decreased acid excretion and increased bicarbonate excretion. Toxins that result in acidic metabolites may trigger lactic acidosis. Rhabdomyolysis, a muscle-wasting disease, is a rare cause of metabolic acidosis.

Mnemonics Various mnemonics are used to assist clinicians in the detection and diagnosis of conditions that may result in high anion gap metabolic acidosis: The newer 2008 mnemonic "GOLD MARK" was proposed in The Lancet reflecting current causes of anion gap metabolic acidosis:

G — glycols (ethylene glycol & propylene glycol) O — oxoproline, a metabolite of paracetamol (acetaminophen) L — L-lactate, the chemical responsible for lactic acidosis D — D-lactate M — methanol A — aspirin R — renal failure K — ketoacidosis, ketones generated from starvation, alcohol, and diabetic ketoacidosis 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 — Paracetamol, Propylene glycol (used as an inactive stabilizer in many medications; historically, the "P" also stood for Paraldehyde, though this substance is not commonly used today) I — Infection, Iron, Isoniazid (which can cause lactic acidosis in overdose), Inborn errors of metabolism (an especially important consideration in pediatric patients) 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 Yet another frequently used mnemonic is KULT.

K — Ketoacidosis (DKA, Alcoholic ketoacidosis) U — Uremia L — Lactic acidosis T — Toxins (Ethylene glycol, methanol, as well as drugs, such as aspirin, Metformin) The mnemonic for toxins is ACE GIFTs: Aspirin, Cyanide, Ethanolic ketosis, Glycols (ethylene and propylene), Isoniazid, Ferrous iron, Toluene, salicylates. Most of these cause a lactic acidosis.

Other formaldehyde toluene sulfates metformin rhabdomyolysis

See also Normal anion gap acidosis Pseudohypoxia

References

External links

Illustrations

Worked examples

Example 1 — a first encounter with High anion gap metabolic acidosis

Start with the simplest possible case. Write down what High anion gap metabolic acidosis claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In chemistry, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to High anion gap metabolic acidosis before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about High anion gap metabolic acidosis ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of High anion gap metabolic acidosis

In research: High anion gap metabolic acidosis appears in chemistry research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses High anion gap metabolic acidosis in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: High anion gap metabolic acidosis is common in secondary-school and first-year university syllabi. It links to neighbouring topics Kidney diseases, Metabolic disorders, Mnemonics, so understanding it makes those chapters shorter.
In everyday life: Look for High anion gap metabolic acidosis outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study High anion gap metabolic acidosis in 20 minutes

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Frequently asked questions

What is High anion gap metabolic acidosis in simple terms?

Why does High anion gap metabolic acidosis matter?

Because it connects several chemistry ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study High anion gap metabolic acidosis?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on High anion gap metabolic acidosis.