Which of the following tests is used to measure iron levels in patients with beta thalassemia?

The ferritin test is the appropriate choice for measuring iron levels in patients with beta thalassemia. Ferritin is a protein that stores iron in the body, and its levels are indicative of the amount of stored iron. In beta thalassemia, patients often require regular blood transfusions, which can lead to iron overload. Monitoring ferritin levels helps evaluate the degree of iron accumulation and guides the need for chelation therapy or other interventions to prevent complications associated with excess iron.

Other options, such as HLA typing, are focused on determining tissue compatibility, often used in the context of organ transplantation or finding suitable donors for stem cell transplants, which is not relevant to measuring iron levels. An ophthalmologic exam assesses eye health and vision, but it does not provide information about iron status. Similarly, an echocardiogram evaluates heart function and structure but does not assess iron levels. Therefore, the ferritin test is specifically designed for the purpose of measuring iron levels, making it the most suitable choice in this context.