Which of the following conditions is characterized by an increase in the levels of carboxyhemoglobin in the blood?

A Carbon monoxide poisoning ✓
B Methemoglobinemia
C Sickle cell anemia
D Iron deficiency anemia

Explanation

Carbon monoxide poisoning is characterized by an increase in the levels of carboxyhemoglobin in the blood, which reduces the ability of hemoglobin to bind oxygen.

Source

Harrison's Principles of Internal Medicine
Hematology Hematology: Hemoglobin and Oxygen Transport Hematology: Hemoglobin and Oxygen Transport Easy MEDICAL Confidence: high