Is a neutrophil (NEUT) percentage of 73.6 normal in a patient suspected of infection?

Is a Neutrophil Percentage of 73.6% Normal in a Patient Suspected of Infection?

A neutrophil percentage of 73.6% is moderately elevated and warrants clinical evaluation for bacterial infection, though it does not reach the threshold (>90%) that carries the highest likelihood of serious bacterial infection. 1, 2

Understanding the Clinical Significance

The neutrophil percentage of 73.6% falls into an intermediate zone that requires careful clinical correlation:

• Normal reference range: Healthy individuals typically have neutrophil percentages well below 70% 1
• Your value of 73.6% is elevated but does not meet the high-risk threshold of >90% (which has a likelihood ratio of 7.5 for bacterial infection) 1, 2
• Most diagnostically powerful markers for bacterial infection, in order of predictive value, are: absolute band count ≥1,500 cells/mm³ (likelihood ratio 14.5), neutrophil percentage >90% (likelihood ratio 7.5), left shift ≥16% bands (likelihood ratio 4.7), and total WBC ≥14,000 cells/mm³ (likelihood ratio 3.7) 1, 2

Critical Next Steps Required

You must obtain a manual differential count immediately to properly assess this leukocytosis, as automated analyzers are insufficient for detecting left shift and band forms. 1, 3, 4

Calculate These Specific Parameters:

• Absolute band count: If ≥1,500 cells/mm³, this has the highest likelihood ratio (14.5) for documented bacterial infection, even without fever 1, 3, 2
• Band percentage: If ≥16%, this represents a left shift with likelihood ratio of 4.7 for bacterial infection 1, 3, 2
• Total WBC count: If ≥14,000 cells/mm³, likelihood ratio is 3.7 for infection 1, 3, 2

Clinical Decision Algorithm

If Manual Differential Shows Left Shift (bands ≥1,500 or ≥16%):

• Perform targeted assessment for occult bacterial infection even if the patient appears asymptomatic, as there is high probability of underlying infection without fever or obvious symptoms 1, 3
• Obtain blood cultures if systemic infection is suspected 2, 4
• Perform site-specific cultures and imaging as clinically indicated 2, 4
• Consider chest radiograph if any respiratory symptoms present 4

If No Left Shift Present:

• In the absence of fever, left shift, or specific clinical manifestations of focal infection, additional diagnostic tests may not be indicated due to low potential yield 1, 3
• However, nonbacterial infections cannot be excluded 1

Critical Pitfalls to Avoid

• Do not ignore elevated band counts when total WBC is only mildly elevated—left shift is more predictive than total WBC count alone 3, 2
• Do not rely on automated differential alone—manual differential is essential to accurately assess band forms 1, 3, 4
• Do not obtain urinalysis/urine culture in asymptomatic residents, even with leukocytosis, as bacteriuria does not indicate infection in the absence of urinary symptoms 1, 3
• Do not ignore a neutrophil percentage of 73.6% when the total WBC is normal, as left shift can occur with normal WBC and still indicate bacterial infection 3, 2

Special Considerations

In older adults or long-term care facility residents, typical symptoms and signs of infection are frequently absent, making laboratory findings more critical for detection. 1, 3, 4 Left shift has particular diagnostic importance in these populations due to atypical presentations. 4