Re‑Thinking “Normal”: Absolute Neutrophil Count by Duffy Status

Join Dr. Maureen Achebe and Dr. Lauren Merz for an in‑depth exploration of the Absolute Neutrophil Counts (ANC) by Duffy Status project, a multicenter effort to define what “normal” ANC and white blood cell counts (WBC) look like in people with the erythrocyte Duffy null variant. Using data from 23 sites across the United States, the project established Duffy null-specific ANC and WBC reference intervals for both adults and children as well as highlighted how often healthy Duffy null individuals have ANC and WBC that fall below conventional laboratory cutoffs. 

The episode unpacks the key findings: in healthy adults with Duffy null status, the ANC reference interval has a lower limit of normal near 1,000/µL, substantially below many institutional “normal” thresholds and far below the traditional neutropenia threshold of 1,500/uL. Similar downward shifts are seen across pediatric age groups with lower limits of normal ranging from 500/uL to 900/uL depending on age category. The faculty discuss how, under current institutional ranges, a sizeable proportion of otherwise healthy Duffy null patients are labeled as neutropenic or leukopenic which often prompts unnecessary workups, referrals, and reduced access to clinical trials or certain medications.  

Drs. Merz and Achebe then turn to implementation. They outline how laboratories can develop, verify, and adopt Duffy null-specific reference intervals and practical ways to integrate this information into electronic medical records, decision-support tools, and clinical communication. They also highlight education strategies for clinicians, trainees, and patients to ensure that a low ANC in a Duffy‑null individual is interpreted appropriately and not reflexively pathologized. 

Listeners will come away with a clear understanding of new adult and pediatric Duffy null-specific ANC and WBC reference intervals as well as practical steps to implement this data into the healthcare system and clinical practice.

Learning Objectives: 

1. Describe how adult and pediatric Duffy null-specific ANC and WBC reference intervals were established and why traditional institutional ranges are inadequate for this population. 

2. Understand how to interpret ANC and WBC values in patients with the Duffy null phenotype using the new reference intervals.

3. Identify practical steps for health systems to adopt Duffy null‑specific reference intervals and effectively communicate these changes to colleagues, patients, and learners.

Clinical Pearls: 

1. In healthy adults with Duffy null status, the lower limit of normal ANC is 1,000/µL—meaning many healthy individuals are misclassified as neutropenic or abnormal by current standards.  

2. The lower limit of normal ANC for Duffy null children ranges from 500-900/uL with approximately a third of children with ANC <1500/uL.   

3. Implementation of Duffy null-specific infrastructure depends on coordinated efforts with a multidisciplinary team including transfusion medicine, clinical pathology, hematology, EMR IT, health equity specialists, medical educators, and patient advocates.