What is the next step in evaluating and treating a patient with low MCH and MCHC values and elevated RDW?

From the Guidelines

The next step in evaluating a patient with low MCH and MCHC values and elevated RDW is to perform a complete iron panel, including serum iron, total iron binding capacity (TIBC), transferrin saturation, and ferritin levels, as these laboratory values strongly suggest iron deficiency anemia. The patient's low MCH and MCHC values indicate hypochromia, which is a characteristic feature of iron deficiency anemia, and the elevated RDW suggests a wide range of red cell sizes, which is also consistent with iron deficiency anemia 1.

Additional testing should include a complete blood count (CBC) if not already done, and a peripheral blood smear to evaluate red cell morphology. Depending on the patient's history, testing for occult blood in stool may be warranted to identify potential gastrointestinal bleeding. If iron deficiency is confirmed, oral iron supplementation should be initiated, typically with ferrous sulfate 325 mg taken 1-2 times daily between meals with vitamin C to enhance absorption.

Some key points to consider in the evaluation and treatment of iron deficiency anemia include:

• Serum ferritin is the most specific test for iron deficiency in the absence of inflammation, with a level of <15 μg/L being highly specific for iron deficiency 1
• A ferritin level of <30 μg/L is generally indicative of low body iron stores, and a level above 150 μg/L is unlikely to occur with absolute iron deficiency, even in the presence of inflammation 1
• The presence of inflammation can affect the interpretation of serum ferritin levels, and a cut-off of 45 μg/L has been suggested as providing the optimal trade-off between sensitivity and specificity for iron deficiency in practice 1
• The choice of treatment for iron deficiency anemia should be based on the distinction between iron deficiency and anemia of chronic disease, and the underlying cause of iron deficiency must be investigated and addressed 1.

Treatment should continue for 3-6 months even after hemoglobin normalizes to replenish iron stores, and the underlying cause of iron deficiency must be investigated, which may include endoscopy or colonoscopy in adults to rule out gastrointestinal bleeding sources, or evaluation of menstrual blood loss in women of reproductive age 1.

From the Research

Evaluation and Treatment of Low MCH and MCHC Values and Elevated RDW

The patient's lab results show low MCH and MCHC values, as well as an elevated RDW. To evaluate and treat this condition, the following steps can be taken:

• Check for iron, vitamin B12, and folate deficiencies, as these can cause low MCH and MCHC values, and elevated RDW 2, 3
• Consider the possibility of cold agglutination and lipid blood interference, which can cause false elevation of MCHC 4
• Use RDW as a sensitive test to detect early iron, folate, and B12 deficiencies, with a global specificity of 74% 2
• Evaluate the patient's RDW value, as it has been associated with worsened pulmonary function, respiratory failure, and poor prognosis in various diseases 5, 6
• Consider the patient's clinical parameters, such as overall survival, and assess the prognostic impact of RDW and other RBC parameters 6

Possible Causes and Associations

The patient's low MCH and MCHC values, and elevated RDW may be associated with:

• Iron deficiency anemia, which can cause microcytosis, low MCH and MCHC values, and elevated RDW 2, 3
• Folate and B12 deficiencies, which can cause macrocytosis, low MCH and MCHC values, and elevated RDW 2
• Respiratory failure, which has been associated with elevated RDW values in critically ill children 5
• Poor prognosis in patients with glioblastoma, which has been associated with elevated RDW values 6

Next Steps

The next steps in evaluating and treating the patient's condition may include:

• Ordering additional lab tests to check for iron, vitamin B12, and folate deficiencies
• Correcting any interfering factors that may be causing false elevation of MCHC
• Monitoring the patient's RDW value and clinical parameters to assess the effectiveness of treatment
• Considering the patient's overall clinical picture and medical history to determine the underlying cause of their low MCH and MCHC values, and elevated RDW 2, 4, 3, 5, 6