The Immature Reticulocyte Fraction Predicts Marrow Recovery and Can Obviate the Need for Bone Marrow Examination in Persistently Neutropenic Cancer Patients

Prolonged and persistent neutropenia (white blood cell (WBC) ≤1000/μL) after chemotherapy is associated with increased risk for infection in cancer patients and is often an indication for a diagnostic bone marrow aspirate and biopsy. A test that predicts WBC recovery ≥ 1000/μL and that obviates the need for marrow sampling would be of clinical value. The immature reticulocyte fraction (IRF) reflects erythroid production and hence a recovering marrow.

We identified 17 myeloma patients with prolonged pancytopenia after either myeloablative or non-myeloablative chemotherapy between March 2010 and February 2011, and compared the time of occurrence of IRF doubling (IRF-D) to the findings on bone marrow examination.

The time to IRF doubling preceded increase of WBC ≥ 1000/μL in 15 of 17 patients by a mean of 4.5 days (range 0–18 days). In two patients, the IRF-D coincided with WBC ≥ 1000/μL. The IRF doubled 2–4 days before the bone marrow examination in four patients and at a mean of 3.7 days (range 1–13 days) after the marrow examination in the remaining 13.

We conclude that the IRF-D is a simple, inexpensive and widely available test that can precede marrow recovery by several days and may therefore obviate the need for a diagnostic bone marrow aspirate and biopsy in patients with prolonged and persistent neutropenia.

No relevant conflicts of interest to declare.