Investigation and Management of Erythrocytosis and Nutritional Deficiencies

Initial Assessment and Evaluation

A complete workup for iron deficiency and vitamin B12 deficiency is recommended, including reticulocyte count, iron studies, and methylmalonic acid levels to confirm deficiencies and rule out underlying causes, in a patient with erythrocytosis, elevated hematocrit, thrombocytosis, normal hemoglobin, low ferritin, and low B12 1, 2
The patient presents with a complex hematologic picture, suggesting a mixed nutritional deficiency pattern with potential bone marrow response issues, characterized by high RBC count, high hematocrit, high platelets, normal hemoglobin, low ferritin, and low B12 1, 3
Abnormalities in multiple cell lines warrant careful evaluation and may require hematology consultation, given the presence of high RBC and platelet counts 1, 4

Complete iron studies should be obtained, including serum ferritin, transferrin saturation, serum iron levels, and percent hypochromic red blood cells, to assess iron deficiency in a patient with low ferritin and normal hemoglobin 2, 3, 5
Low ferritin with normal hemoglobin but high RBC count suggests a compensatory response to iron deficiency, which may be related to gastrointestinal blood loss or other underlying causes 3, 6

Homocysteine levels can be used as an additional marker of functional B12 deficiency, to further investigate low B12 levels and potential causes of B12 malabsorption 7

Reticulocyte count and complete blood count with red cell indices can help assess bone marrow response and characterize the anemia pattern, in a patient with erythrocytosis and nutritional deficiencies 1, 2, 4, 6
Inflammatory markers, such as CRP, and kidney function tests can help assess for inflammation and renal causes of erythrocytosis, which may impact interpretation of ferritin levels and guide further management 1, 2, 5
The potential impact of medications, such as amlodipine, on hematologic parameters should be evaluated, and consideration given to whether other medications may affect B12 absorption 4