1. What is the I/T Ratio?

The I/T (Immature to Total neutrophil) ratio is a calculation used in neonatal care to assess the risk of early-onset sepsis in newborns. It compares the number of immature neutrophils to the total neutrophil count in a blood sample.

2. How Does the Calculator Work?

The calculator uses the I/T Ratio formula:

Where:

• Immature Neutrophils — Count of immature neutrophils (bands, metamyelocytes, myelocytes)
• Total Neutrophils — Sum of both mature and immature neutrophils

Explanation: The ratio provides a standardized measure of neutrophil immaturity, which increases in response to infection.

3. Importance of I/T Ratio in Neonatal Care

Details: The I/T ratio is a valuable screening tool for neonatal sepsis. A ratio greater than 0.2-0.3 in term infants or 0.25 in preterm infants is often considered abnormal and may indicate infection.

4. Using the Calculator

Tips: Enter the immature neutrophil count and total neutrophil count from a complete blood count (CBC) with manual differential. Both values must be valid (immature ≤ total, total > 0).

5. Frequently Asked Questions (FAQ)

Q1: What is a normal I/T ratio in newborns?
A: In healthy term infants, the I/T ratio is typically less than 0.16 during the first 60 hours of life. Values above 0.2-0.3 are considered abnormal.

Q2: How does the I/T ratio change with gestational age?
A: Preterm infants may have slightly higher normal ranges. The cutoff for abnormality is often set at 0.25 for preterm infants compared to 0.2 for term infants.

Q3: When should I/T ratio be measured?
A: The I/T ratio is most useful in the first 24-48 hours of life when evaluating for early-onset sepsis. It's typically part of a sepsis workup that includes other laboratory tests and clinical assessment.

Q4: Are there limitations to the I/T ratio?
A: The I/T ratio has moderate sensitivity but poor specificity for neonatal sepsis. It should be interpreted in the context of other clinical findings and laboratory values, not used in isolation.

Q5: How does the I/T ratio compare to other sepsis markers?
A: The I/T ratio is one of several hematologic indices used for sepsis screening. It's often used alongside absolute neutrophil counts, C-reactive protein, and other inflammatory markers.