What Does a “low Anion Gap” Mean Physically?

Physically, a low anion gap is a smaller-than-normal difference between positively and negatively charged ions in bodily fluids, says Lab Tests Online. High and low anion gaps are symptoms of blood pH problems; the balance of positively and negatively charged ions dictates how acidic or alkaline the blood is.

A low anion gap does not cause physical symptoms, but it is associated with conditions such as hypoalbuminemia, liver cirrhosis, intestinal obstruction and multiple myeloma. These conditions cause a low anion gap because they lower the levels of albumin, a negatively charged protein in the blood. The body retains other negatively charged ions to make up for this loss.

This condition sometimes occurs in patients with normal levels of albumin. In these cases the body produces abnormally high levels of positively charged proteins. This most commonly happens with the protein immunoglobulin. When it does, it is referred to as paraproteinemia, which is a symptom of underlying immune system problems.

An electrolyte panel measures the anion gap, among other things. The most common reasons for this test are sodium or potassium imbalances and acid-base imbalances. Doctors also use this test to diagnose diabetic acidosis and to detect some types of poisoning. Substances that cause a high anion gap include methanol, antifreeze, aspirin and cyanide.