In metabolic acidosis, what are the expected values for pH, PCO2, and HCO3?

• A. Decreased pH, Normal PCO2, Decreased HCO3
• B. Increased pH, Normal PCO2, Increased HCO3
• C. Normal pH, Increased PCO2, Decreased HCO3
• D. Decreased pH, Increased PCO2, Normal HCO3

Answer: (A)

In metabolic acidosis, the hallmark feature is a decrease in bicarbonate (HCO3) levels. This depletion of bicarbonate results in a compensatory response from the respiratory system, which attempts to normalize the pH by increasing the exhalation of carbon dioxide (CO2). As a result, the pH decreases due to the presence of excess hydrogen ions, and the compensatory mechanism leads to a reduction in PCO2.

Thus, in metabolic acidosis, one can expect the following values:

• The pH is decreased, indicating an acidic environment in the body.

• The PCO2 is typically reduced as the body attempts to compensate for the acidosis through hyperventilation.

• HCO3 is decreased since metabolic acidosis means there has been a primary loss of bicarbonate, making it an essential marker for identifying this condition.

These changes illustrate the body's compensatory mechanisms and help in understanding the underlying pathophysiology of metabolic acidosis. The expected laboratory findings align directly with this physiological response, confirming that the correct answer involves decreased pH, normal PCO2, and decreased HCO3.