An anion gap blood test is a way to check the acid-base balance (pH balance) of your blood and to determine if your blood is too acidic or not acidic enough. The anion gap measures the difference between the negatively charged and positively charged electrolytes in your blood. If the anion gap is too low, it means that your blood isnt acidic enough. A low anion gap test result may mean you have alkalosis (blood that is less acidic than normal) . However, this result is so rare that your healthcare provider will usually have you tested again to make sure the results are accurate. The most common cause of a low anion gap is a low level of albumin, a protein in the blood. Low anion gap results are uncommon, and sometimes its due to a lab error. If you really do have a low anion gap, it could mean your blood doesnt have enough of a protein called albumin. That can be a sign of conditions like hypoalbuminemia, which involves having too little of an essential protein called albumin in the blood. Hypoalbuminemia usually occurs because of inflammation throughout the body, sepsis, recent surgery, malnutrition, severe burns, liver or kidney disease, hyperkalemia, which is high potassium, hypercalcemia, which is high calcium, and certain types of cancer. A low anion gap level is rare and indicates an abnormally high level of positively charged molecules. The most common cause of which is multiple myeloma, a cancer of a class of white blood cells called plasma cells.