1. What is the I/T Ratio?

The I/T (Immature to Total) neutrophil ratio is a hematologic parameter used primarily in newborns to assess for bacterial infection. It compares the number of immature neutrophils to the total neutrophil count.

2. How Does the Calculator Work?

The calculator uses the simple formula:

Where:

• \( Immature\_neutrophils \) — Count of immature neutrophils (bands, metamyelocytes, myelocytes)
• \( Total\_neutrophils \) — Count of all neutrophils (mature + immature)

Explanation: The ratio provides a percentage of immature neutrophils in circulation, which increases during bacterial infections.

3. Importance of I/T Ratio

Details: In newborns, an I/T ratio >0.2-0.3 is considered abnormal and may indicate early-onset sepsis. It's particularly useful when clinical signs are equivocal.

4. Using the Calculator

Tips: Enter absolute counts (not percentages) of immature and total neutrophils from a complete blood count with manual differential.

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 possible infection.

Q2: How is the manual differential performed?
A: A trained technician examines 100 white blood cells under microscope to classify them.

Q3: Does this apply to premature infants?
A: Premature infants may have higher baseline I/T ratios. Gestational age-specific norms should be considered.

Q4: What other tests complement the I/T ratio?
A: CRP, procalcitonin, complete blood count, and clinical assessment are often used together.

Q5: How quickly does the I/T ratio change with infection?
A: The ratio can rise within hours of bacterial infection, making it an early marker.