Low bicarbonate levels in the blood means that the body has an acid-base imbalance or an electrolyte imbalance, according to Lab Tests Online. Low bicarbonate levels may be due to metabolic acidosis, diabetic ketoacidosis, kidney disease, Addison's disease, chronic diarrhea, methanol, or ethylene glycol or aspirin poisoning.
Doctors usually order the bicarbonate test together with other electrolytes, such as sodium, chloride, and potassium, or together with blood gases and blood pH, explains Lab Tests Online. Acidosis occurs when the pH of blood is less than 7.35. Metabolic acidosis occurs when the level of bicarbonate is low and there is acidosis. The kidneys regulate the concentration of bicarbonate in the blood.
Metabolic acidosis can occur as a result of kidney disease; diarrhea; metabolic disease, such as diabetes; and several drugs and poisons, notes Lab Tests Online. Some drugs, such as methicillin, nitrofurantoin, tetracycline, thiazide diuretics and triamterene, can decrease bicarbonate levels.
High bicarbonate levels are associated with metabolic alkalosis and may be due to severe vomiting, lung disease, Cushing syndrome and Conn syndrome. Alkalosis occurs when the pH of blood is above 7.45. Drugs that can increase bicarbonate levels include steroids, fludrocortisone, loop diuretics, bicarbonates and barbiturates, according to Lab Tests Online.