Evaluation and Management of Leukocytosis with Neutrophilia and Elevated RDW
Initial Assessment
Your patient's laboratory findings (WBC 13.5, neutrophils 73.9%, RDW 14.5%) warrant systematic evaluation for bacterial infection, as this combination carries a likelihood ratio of 3.7 for underlying bacterial infection even without fever. 1, 2
The neutrophil percentage of 73.9% is moderately elevated and requires clinical correlation, though it does not reach the >90% threshold that carries the highest likelihood (7.5) of serious bacterial infection. 1
Critical Next Steps
Mandatory Laboratory Evaluation
Obtain a manual differential count immediately to assess for left shift (≥16% band neutrophils), which has a likelihood ratio of 4.7 for bacterial infection even with normal total WBC count. 1, 2, 3
Calculate the absolute band count - if ≥1,500 cells/mm³, this carries the highest likelihood ratio (14.5) for documented bacterial infection and is the most diagnostically powerful marker. 1, 2, 3
Do not rely on automated analyzer alone, as manual differential is essential to accurately assess band forms and immature neutrophils. 4, 3
Focused Clinical Examination
Systematically evaluate for infection sources:
Vital signs: Check for fever >38°C or hypothermia <36°C, hypotension <90 mmHg systolic, tachycardia, tachypnea. 2
Respiratory system: Assess for cough, dyspnea, chest pain, hypoxemia suggesting pneumonia. 2, 3
Urinary tract: Evaluate for dysuria, flank pain, frequency, new or worsening incontinence. 4, 2, 3
Skin/soft tissue: Examine for erythema, warmth, purulent drainage, cellulitis. 2, 3
Gastrointestinal: Check for abdominal pain, peritoneal signs, diarrhea suggesting intra-abdominal infection. 1, 2, 3
Targeted Diagnostic Testing
Urinalysis with leukocyte esterase/nitrite dipstick and microscopic examination - if pyuria present, obtain urine culture as UTI is a common occult source in adults. 2, 3
Blood cultures if any signs of systemic infection are present (fever, hypotension, tachycardia, altered mental status). 2, 3
Chest radiography if respiratory symptoms or hypoxemia documented. 3
Lactate level - if >3 mmol/L, indicates severe sepsis requiring immediate intervention. 2
Red Blood Cell Parameters
The elevated RDW% at 14.5% combined with low MCH (26.9) and low MCHC (30.3) suggests iron deficiency anemia or anemia of chronic disease, which commonly accompanies active infection or inflammatory states. 4
Management Algorithm
If Patient is Hemodynamically Stable:
Complete the diagnostic workup outlined above before initiating antibiotics. 2
Do not treat based solely on laboratory findings without clinical correlation if patient is asymptomatic. 2, 3
If Sepsis Criteria Present:
Initiate broad-spectrum empiric antibiotics within 1 hour of recognition. 2
Aggressive fluid resuscitation for hypotension. 2
Vasopressor support if hypotension persists despite fluids. 2
Source control measures (drainage of abscesses, removal of infected catheters). 2
Critical Pitfalls to Avoid
Do not ignore elevated neutrophil count when total WBC is only mildly elevated - left shift can occur with normal WBC and still indicate serious bacterial infection. 1, 2, 3
Do not overlook the significance of absolute neutrophil count elevation when total WBC is only mildly elevated. 1
Do not delay antibiotics in severe sepsis/septic shock while awaiting culture results. 2
Do not treat asymptomatic patients with antibiotics based solely on mildly elevated neutrophil counts. 1, 2
Alternative Considerations
If no infection source is identified after thorough evaluation:
Consider non-infectious causes including medications (lithium, beta-agonists, epinephrine). 1, 3
Evaluate for tissue damage or inflammatory conditions (trauma, surgery, ischemia) which can cause persistent inflammation-immunosuppression and catabolism syndrome (PICS). 5
The low monocyte count (2.4%) is notable, as monocyte counts tend to decrease during acute bacterial processes. 4