AAB Medical Technologist (MT) – Hematology Practice Exam 2026 - Free Hematology MT Practice Questions and Study Guide

The correct choice is Carboxyhemoglobin, which has a much greater binding capacity for the hemoglobin molecule than oxygen. Carboxyhemoglobin is formed when carbon monoxide (CO) binds to hemoglobin, and this binding is significantly stronger than that of oxygen. In fact, carbon monoxide has an affinity for hemoglobin approximately 200-250 times greater than that of oxygen, which can lead to serious physiological effects, including hypoxia, as it effectively prevents oxygen from binding and being delivered to tissues.

The importance of recognizing carboxyhemoglobin arises from its clinical implications; exposure to carbon monoxide is a serious health risk and can occur in situations involving incomplete combustion of fuels. Understanding its binding capacity emphasizes the risks of carbon monoxide poisoning and the need for prompt recognition and treatment.

In contrast to carboxyhemoglobin, oxyhemoglobin (the form of hemoglobin bound to oxygen) is essential for oxygen transport, while methemoglobin is a form of hemoglobin that cannot effectively carry oxygen, due to the iron within it being oxidized to the ferric state. Sulfhemoglobin, another variant, arises from the irreversible binding of sulfur to hemoglobin and also does not effectively transport oxygen. This context highlights the significance of carbox