Abnormal CO2 levels in the blood may mean that a patient is losing or retaining fluid, according to MedlinePlus. This may imbalance the patient's electrolytes, which are minerals in the body fluids that carry electric charges and help regulate metabolism.
As CO2 is expressed in the blood as bicarbonate, a CO2 test actually measures the levels of bicarbonate, states MedlinePlus. To test her CO2 levels, a patient has blood drawn from the back of her hand or her elbow. The normal levels of CO2 are between 23 to 29 milliequivalents per liter. Lower levels may mean that the patient is suffering from diarrhea, ketoacidosis or poisoning by ethylene glycol. She may also be suffering from lactic or metabolic acidosis, methanol poisoning or an aspirin overdose. Addison disease also affects CO2 levels. It occurs when the adrenal glands, which sit on top of the kidneys, don't make enough hormones, explains Mayo Clinic.
If CO2 levels are higher than normal, the patient may have Cushing syndrome, hyperaldosteronism or breathing disorders, notes MedlinePlus. In Cushing syndrome, the body makes too much of the hormone cortisol, states Healthline. The patient's electrolytes could also have been disordered through vomiting, dementia, delirium or alkalosis. Distal or proximal renal tubular acidosis also affects CO2 levels.