What is High Anion Gap Metabolic Acidosis?
High anion gap metabolic acidosis (HAGMA) is a specific type of acidosis- a condition where the body’s fluids contain too much acid. This happens because of a metabolic issue, and not a respiratory one. Acidosis is classified into two types: high anion gap metabolic acidosis and non-anion gap metabolic acidosis. Determining which type of acidosis a patient has can help doctors understand the cause of the condition and thus, figure out the best way to treat it.
What Causes High Anion Gap Metabolic Acidosis?
Remembering the numerous causes of high anion gap metabolic acidosis, a condition where the body’s fluids contain too much acid, can be challenging. However, the acronym “GOLD MARK” has become popular because it specifically focuses on the most common causes in the modern world.
The letters in “GOLD MARK” stand for:
- Glycols: Types of simple alcohols, specifically ethylene glycol and propylene glycol.
- Oxoproline: A toxic compound that can build up due to an overdose of drugs like acetaminophen (also known as paracetamol).
- L-Lactate: This is the standard lactic acid that’s present in the body when there’s too much acid (what we call lactic acidosis).
- D-Lactate: This is a specific type of lactic acid made by gut bacteria.
- Methanol: This stands for alcohols in general.
- Aspirin: Scientifically known as salicylic acid.
- Renal Failure: Also known as uremic acidosis, this is when the kidneys aren’t removing enough acid from the body.
- Ketones: These are produced by the body during starvation or when a diabetic or alcoholic person’s body can’t use sugar for energy.
It’s interesting to note that the drug metformin isn’t included in this list. This is because, according to a review by Cochrane, it doesn’t lead to lactic acidosis. However, an older drug called phenformin does raise the chances of developing lactic acidosis by ten times.
Lastly, “GOLD MARK” should also include ‘massive rhabdomyolysis’. This is a condition where muscle breaks down rapidly, releasing a large amount of hydrogen ions that can cause the body fluids to become acidic.
Risk Factors and Frequency for High Anion Gap Metabolic Acidosis
High anion gap metabolic acidosis is a frequent condition seen in critically ill patients. However, precise figures are not easily accessible.
Signs and Symptoms of High Anion Gap Metabolic Acidosis
High anion gap metabolic acidosis is a type of acid imbalance in the body that can cause various symptoms. Most of these are not specific to this condition, which means they could be common to many other conditions as well. Labored breathing or shortness of breath is quite typical, as this condition triggers the respiratory center in your brain to work harder. Understanding the signs linked with different causes of this type of acidosis can be useful.
- Checking for toxic ingestions, like taking too much aspirin or acetaminophen, is crucial.
- Looking for signs of diabetes, such as excessive urination, extreme thirst, and increased hunger, is also important.
- Signs of kidney failure should be monitored for, this may include frequent nighttime urination, itching, and loss of appetite.
Physical signs are often not specifically tied to metabolic acidosis. However, deep, slow breathing (rather than shallow fast breaths), known as Kussmaul respirations, is usually observed. Recognizing the signs of specific causes can help narrow down potential conditions leading to this acidosis.
- For example, a patient with diabetic ketoacidosis might have dry mucous membranes and a fruity or sweet breath odor.
- Alternatively, a patient with uremia might show signs of skin scratching, involuntary hand fluttering (asterixis), and confusion.
Testing for High Anion Gap Metabolic Acidosis
Patients experiencing high anion gap metabolic acidosis often show non-specific symptoms, making the condition challenging to identify. The term “anion gap” refers to the difference between the major positively charged electrolyte in your blood (sodium) and the major negatively charged electrolytes (chloride and bicarbonate). To diagnose this condition, doctors need to notice complex chemical changes in your body. They do this by conducting tests to calculate the anion gap, which starts with a basic metabolic panel or a serum electrolyte panel.
For the most accurate diagnosis, medical professionals should take into account other factors that may affect the anion gap, such as significant changes in potassium levels, or fluctuations in the amount of albumin, a protein in your blood. If there is too little albumin in your blood, the anion gap can be falsely lowered, potentially concealing the presence of high anion gap metabolic acidosis.
Typically, a normal anion gap falls between 8 to 12 milliequivalents per liter (mEq/L). If the anion gap goes above 12, that indicates an excess of unmeasured negatively charged particles (anions). To find out the source of these anions, doctors often conduct further tests. These tests typically screen for the presence of certain substances – including ethanol, acetaminophen (a common pain reliever), lactate (a compound produced by the body), salicylic acid (used in pain relievers), creatinine (a waste product), and ketones (molecules your body makes when it burns fat). Rendered in simple terms, the more of these substances are in your body, the higher your anion gap tends to be.
In many cases, it’s necessary to look at the osmolar gap too, which is the difference between the actual measurement of particles in your blood, and the calculated number of these particles. An elevated osmolar gap can suggest the presence of toxic alcohols – but it can also be a sign of ketoacidosis, a condition that develops when your body starts to run out of insulin. In such cases, tracking the changes in the osmolar gap can help assess the effectiveness of your treatment. If the gap doesn’t decrease with treatment, medical professionals will often investigate the possibility of ingesting toxic alcohol.
Additional tests might include a blood gas test, a urine test, a complete blood count (that measures different cells in your blood), and checks for any related respiratory or metabolic disturbances. Doctors may even consider performing an EKG (a test that detects heart problems by tracking electrical signals in your heart) and abdominal radiography (spotting any abnormal objects in your abdomen) to help pinpoint the cause of the abnormal anion and osmolar gaps.
Treatment Options for High Anion Gap Metabolic Acidosis
The main approach to treat high anion gap metabolic acidosis, a condition that involves an excess of acid in the body, is to address the root cause. For mild to moderate cases, supportive care might be all that’s needed. This can include giving fluids through an IV and assistance with breathing.
Therapy that works to restore the body’s pH level, also known as alkalization therapy, is typically used only for severe cases where the pH drops below 7.1. In people with diabetic ketoacidosis (a severe diabetes complication where the body produces excess blood acids known as ketones), this threshold is even lower, with a pH less than 6.9.
The type of medication commonly used to raise the pH level is sodium bicarbonate. However, sodium and potassium citrate are other options. If the acidosis is very serious and not improving, doctors might use alcohol dehydrogenase inhibitors, such as fomepizole or ethanol. These medications work by stopping the conversion of alcohols into harmful substances in the body.
It’s important to note that fomepizole tends to be most effective when given within six hours of the patient’s arrival. But because it can be hard to get and quite expensive, it’s not recommended to treat all cases of high anion gap metabolic acidosis with this medication.
Treating the underlying cause can vary depending on the disease. For example, in diabetic ketoacidosis, this may require glucose and insulin. In the case of sepsis (a life-threatening response to infection), antibiotics and careful fluid administration might be necessary. For toxic ingestions, specific antidotes like fomepizole or n-acetylcysteine (a medication used to thin mucus in the lungs and intestines) may be used.
What else can High Anion Gap Metabolic Acidosis be?
Here’s a list of conditions and substances that can affect your health:
- Diabetic ketoacidosis – A serious complication of diabetes, causing your blood to turn acidic.
- Ethyl glycol – A toxic substance found in antifreeze and some paints.
- Isoniazid – A medicine used to treat tuberculosis, but may cause harmful side effects.
- Lactate – A substance produced by your body. High levels can indicate certain health problems.
- Methanol – A type of alcohol, very toxic to humans if ingested or absorbed through the skin.
- Propylene glycol – A type of alcohol used in certain medicines and products, it may cause harmful effects in large amounts.
- Salicylates – Chemicals found in some medications, too much can be harmful.
- Uraemia – A condition where waste products build up in your blood, usually due to kidney dysfunction.
