1. What is the I/T Ratio?

The I/T (immature to total neutrophil) ratio is a hematologic parameter used in the evaluation of neonatal sepsis. It compares the number of immature neutrophils to the total neutrophil count in a newborn's 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)
• \( Total\_neutrophils \) — Count of all neutrophils (mature + immature)

Explanation: The ratio helps assess the severity of infection in neonates by quantifying the left shift in neutrophil maturation.

3. Importance of I/T Ratio

Details: An elevated I/T ratio (>0.2-0.3) suggests significant bacterial infection in newborns. It's part of the sepsis workup along with clinical findings and other lab tests.

4. Using the Calculator

Tips: Enter the absolute counts of immature and total neutrophils from a manual differential count. Total neutrophils must be greater than zero.

5. Frequently Asked Questions (FAQ)

Q1: What is a normal I/T ratio in newborns?
A: Typically <0.2 in healthy term infants. Values >0.2-0.3 suggest infection, though exact cutoff varies by institution.

Q2: How is the manual differential performed?
A: A trained technician examines 100 white blood cells on a peripheral blood smear to classify neutrophil maturity.

Q3: Are there limitations to the I/T ratio?
A: Yes, it may be elevated in non-infectious conditions like maternal hypertension, perinatal asphyxia, or hemolytic disease.

Q4: How does gestational age affect I/T ratio?
A: Premature infants may have higher baseline ratios. Age-specific reference ranges should be used.

Q5: Should I/T ratio be used alone for sepsis diagnosis?
A: No, it should be interpreted with clinical findings, CRP, blood cultures, and other sepsis markers.