1. What is the I/T Ratio?

The I/T (immature to total) neutrophil ratio is a marker used in pediatrics to assess bacterial infection risk in newborns and young infants. It compares the number of immature neutrophils (bands) to the total neutrophil count.

2. How Does the Calculator Work?

The calculator uses the I/T ratio formula:

Where:

• \( Immature\ Neutrophils \) — Count of band forms and other immature neutrophils
• \( Total\ Neutrophils \) — Sum of mature and immature neutrophils

Explanation: The ratio helps identify a "left shift" in neutrophil maturation, indicating increased bone marrow production in response to infection.

3. Importance of I/T Ratio in Pediatrics

Details: In neonates, an I/T ratio >0.2 is often considered abnormal and may suggest bacterial infection. It's particularly useful in evaluating early-onset sepsis.

4. Using the Calculator

Tips: Enter absolute counts of immature and total neutrophils from a complete blood count (CBC) with differential. Both values must be positive numbers with total neutrophils > 0.

5. Frequently Asked Questions (FAQ)

Q1: What is a normal I/T ratio in newborns?
A: Typically <0.2 in term infants. Preterm infants may have slightly higher normal ranges.

Q2: When is the I/T ratio most useful?
A: Most valuable in the first 24-48 hours of life for evaluating early-onset sepsis.

Q3: What conditions can elevate the I/T ratio?
A: Bacterial infections, stress, maternal fever, perinatal asphyxia, and hemolytic disease.

Q4: Are there limitations to the I/T ratio?
A: Sensitivity and specificity vary. Should be interpreted with clinical context and other lab values.

Q5: How does the I/T ratio compare to absolute neutrophil count?
A: The ratio may be more consistent across gestational ages than absolute counts alone.