When would a serum iron test most likely be ordered by a physician?

A serum iron test is primarily used to assess iron status in the body, often in situations where anemia is suspected. Anemia may arise from several underlying causes, including iron deficiency, which is one of the most common types of anemia. When both hemoglobin and hematocrit levels are low, it typically indicates that anemia is present. In this context, a physician may order a serum iron test to help determine whether the anemia is due to iron deficiency or another cause.

Evaluating serum iron levels provides valuable insight into iron metabolism and storage, helping to identify the root problem and guide appropriate treatment. When hemoglobin and hematocrit are low, it raises the suspicion for iron deficiency anemia, making it a logical point at which to assess iron levels. This insight is essential for managing the patient's condition effectively.

In contrast, high hemoglobin and hematocrit or normal levels in these parameters do not typically warrant a serum iron test as the risk of iron deficiency or its implications is significantly lower. Therefore, serum iron testing is most relevant in the presence of low hemoglobin and hematocrit, where iron deficiency becomes a critical consideration in diagnosing the type of anemia.