Final answer:
The nurse practitioner should first rule out bone marrow failure when a patient treated with EPO does not exhibit reticulocytosis, as the bone marrow is crucial in red blood cell development.
Step-by-step explanation:
When a patient has been treated with EPO (erythropoietin) due to an acute bleeding episode and does not show reticulocytosis, the nurse practitioner needs to consider several other potential causes. Since EPO mainly stimulates red blood cell production, the lack of reticulocytosis could indicate a deeper issue. The next step would be to rule out bone marrow failure. This is because the bone marrow is the site of erythrocyte production, and failure could result in an inadequate response to EPO. Other possible issues like absorption malfunction, acute hepatic malfunction, or kidney failure could contribute to an inadequate erythrocyte count, but given the direct role of the kidneys in EPO production and the bone marrow in RBC development, these would be secondary considerations after first evaluating for bone marrow issues.