Bicarbonate (HCO3) is an electrolyte measured in routine blood tests. Its levels provide insights into overall health, and it is often included in an electrolyte panel that assesses the balance of charged particles in the body.
The Role of Bicarbonate (HCO3)
Bicarbonate is a form of carbon dioxide (CO2) with the chemical formula HCO3-. It is a crucial component of the body’s acid-base buffering system, maintaining blood pH within a narrow, healthy range of approximately 7.35 to 7.45. The body constantly produces acids, and bicarbonate neutralizes them, preventing the blood from becoming too acidic or too alkaline.
The lungs and kidneys work together to regulate bicarbonate levels and blood pH. Lungs control CO2 levels, which quickly affect pH, while kidneys regulate bicarbonate concentration, a slower but equally important process. Measuring bicarbonate levels provides information on how effectively these systems manage the body’s acid-base balance. Even slight deviations in blood pH can disrupt cellular processes and overall body function.
Interpreting HCO3 Levels
Healthcare providers interpret HCO3 levels to understand the body’s acid-base status. The normal reference range for adults is typically 22 to 29 milliequivalents per liter (mEq/L) or millimoles per liter (mmol/L), though this can vary between laboratories. Values outside this range indicate a pH imbalance.
Elevated HCO3 levels, usually above 26 mEq/L, suggest metabolic alkalosis, where the blood becomes too alkaline. This occurs when the body gains too much base or loses too much acid. Symptoms can include confusion, hand tremors, and muscle twitching.
Conversely, decreased HCO3 levels, typically below 22 mEq/L, indicate metabolic acidosis, meaning the blood has become too acidic. This imbalance happens when the body produces too much acid, loses too much bicarbonate, or kidneys cannot remove enough acid. Low bicarbonate can lead to symptoms like fatigue, shortness of breath, and confusion.
Clinical Significance of Abnormal Levels
Abnormal bicarbonate levels can be linked to various medical conditions or physiological states.
Elevated HCO3, indicating metabolic alkalosis, can result from prolonged vomiting, leading to stomach acid loss, or from certain diuretic medications. Other causes include chronic lung diseases like COPD, where the body compensates for respiratory acidity, and hormonal disorders such as Cushing’s syndrome.
Low HCO3 levels, signaling metabolic acidosis, may stem from kidney dysfunction, as kidneys are essential for removing acid and maintaining bicarbonate levels. Diabetic ketoacidosis, a severe complication of diabetes, also leads to a significant bicarbonate drop due to acid accumulation. Other factors include severe diarrhea, causing loss of bicarbonate-rich fluids, and certain medications or toxins.