What are the causes of low anion gaps?
people can have a low anion gap for many reasons. This value, which compares the concentration of positively charged ions in the blood with negatively charged ions in the blood, can become an abnormal series of metabolic disorders. With low albumin levels, negatively charged protein, can cause a reduced anion gap. This change can also cause high concentrations of positively charged proteins. Laboratory error, lithium intoxication and bromide ingestion can also cause a low anion gap.
To understand the meaning of low anion gaps, it helps to understand what the anion gap is, how it is measured and what it means. The anion gap is calculated after measuring concentrations of different serum electrolytes. It is usually calculated by deducting negatively charged substances, including chloride and bicarbonate, from positive substances, including sodium. Normal value is usually around 12. Having a low anion gap is quite rare, and in some studies it turned out to be present in less than 1 percent hosdissected patients.
patients who have reduced albumin levels - a protein made by the liver that circulates in the blood - may have a low anion gap. Albumin has a negative charge, and when the concentration of this protein is reduced in the blood, the body compensates for negatively charged ions, including chloride in the blood. Higher levels of chloride and bicarbonate lead to a reduced anion gap. Patients with liver disease, malnutrition and kidney disease usually reduced the blood albumin levels.
conditions that lead to excessive production of positively charged protein can also cause a reduced anion gap. For example, multiple myeloma is malignancy in which patients produce a large number of proteins that are usually used as antibodies. They have a positive charge as these prices, compensating the body by excretion of positive ions, such as sodium. Therefore, the anion gap will be reduced.
Some intoxications in which patients take negatively charged ions can also cause a low anion gap. Overdose of lithium, which is a drug commonly used to treat bipolar disorders, increases the amount of negative serum ions and reduces the anion gap. A excess bromide can cause a similar effect.
Another cause of low anion gaps is a laboratory error. If the values provided for serum concentrations of sodium, chloride and bicarbonate are incorrect, then the anion gap could be calculated as low if it is actually normal. Doctors or other healthcare professionals should use their clinical judgment when interpreting laboratory values and do not forget to question values that make no sense. The best way to find out if a laboratory error occurs is to check the concentration of electrolyte in serum.