Which of the following abnormalities is characterized by an increased level of bicarbonate?

An increased level of bicarbonate in the body is primarily associated with metabolic alkalosis. In this condition, there is an elevation of bicarbonate concentration often due to either excessive loss of hydrogen ions (for example, through vomiting) or an increased intake of bicarbonate (such as through antacid use). The body compensates for an increase in bicarbonate levels by decreasing respiratory rate to raise carbon dioxide levels, which can further moderate the alkalinity.

In contrast, respiratory acidosis is characterized by elevated carbon dioxide levels due to reduced airflow or ventilation, which leads to conversion to carbonic acid, not bicarbonate. Metabolic acidosis involves a decrease in bicarbonate, typically seen in conditions like diarrhea or diabetic ketoacidosis, where acid accumulates or bicarbonate is lost. Therefore, the correct answer reflects the physiological role of bicarbonate in maintaining the body's acid-base balance during metabolic alkalosis.