Definition

Neonatal sepsis accounts for approximately 1.5 to 2 million infant deaths annually in developing countries. It is a severe infection in newborns, accompanied by systemic inflammation and various signs and symptoms. These symptoms may or may not include bacteremia, a condition where bacteria are present in the bloodstream.

This condition is more common in infants born with low birth weight, respiratory difficulties at birth, or abnormalities during pregnancy. Sepsis, considered a medical emergency, can result from infections caused by viruses, fungi, or parasites. Early signs include fever, hypothermia, chills, rapid heartbeat, low blood pressure, shortness of breath, nausea, vomiting, diarrhea, muscle pain, confusion, and even loss of consciousness.

Blood tests remain the gold standard for diagnosing neonatal sepsis, though results may take 3 to 5 days and can vary. Additional diagnostic methods, including the IT ratio test, are also employed.

The IT ratio test, or Immature-to-Total Neutrophil Ratio, is an auxiliary diagnostic method alongside complete blood counts and C-reactive protein (CRP) tests for infant sepsis. The ratio is calculated by dividing the number of immature neutrophils by the total neutrophil count. Immature neutrophil granulocytes include rod neutrophils, metamyelocytes, myelocytes, and promyelocytes, while mature neutrophils comprise the remainder of the neutrophil population.

Neutrophils play a critical role in the body's immune defense. In newborns, the normal neutrophil count starts at 1,800/mm³, increases to 7,200/mm³ within 12 hours, and stabilizes at 1,800/mm³ later. Sepsis is a leading cause of neonatal mortality, contributing to 30–50% of newborn deaths annually in developing nations. Studies suggest that the IT ratio test is highly sensitive for diagnosing sepsis, though additional research is required to confirm its efficacy.

Indications

The IT ratio test is primarily used in infants to help diagnose sepsis. Clinical symptoms of sepsis in infants may include:

• The infant appears unwell
• Abnormal body temperature (too low or high)
• Hardened or stiff skin (sclerema)
• Digestive issues such as vomiting, bloating, diarrhea, or lack of appetite
• Respiratory problems like rapid breathing, nasal flaring, or breathlessness
• Rapid heartbeat
• Swelling in certain body parts

Contraindications

There are no specific contraindications for the IT ratio test, making it suitable for all patients.

Preparation Prior to Test

The IT ratio test does not require special preparation. It is typically performed by a doctor, especially when newborns display symptoms of neonatal sepsis shortly after birth.

Test Procedure

The IT ratio test typically requires a blood serum sample of 0.25–0.5 ml. The blood is drawn from a vein and collected into a specialized tube. Laboratory staff performing the procedure wear gloves and personal protective equipment (PPE).

To collect the sample, an elastic band is tied around the arm, and the puncture site is cleaned with antiseptic gauze. Blood is usually drawn from a vein near the elbow, but for infants, it is collected from the heel. After obtaining the sample, the elastic band is removed, and the puncture site is pressed and cleaned again with antiseptic gauze.

The procedure is quick, lasting only a few minutes. The blood sample is analyzed in a laboratory using specialized equipment, and results are typically available within a few hours.

Normal and Abnormal Values

The maximum acceptable IT ratio to avoid sepsis within the first 24 hours is 0.16. For most newborns, the IT ratio is approximately 0.12 within the first 60 hours of life. The normal range for the IT ratio is less than 0.2, while an abnormal value is any ratio greater than 0.2 (>0.2).

Results and Recommendations (Follow-up Tests)

The interpretation of IT ratio test results is essential, and your doctor will play a key role in assessing these values. The IT ratio test is typically performed alongside a CRP test. If the IT ratio exceeds 0.2, it may indicate abnormalities or a potential infection that requires medical attention.

Consult the Right Doctor

If your baby's IT ratio test results are abnormal, consult a general practitioner for an accurate diagnosis and appropriate treatment. If necessary, you can also seek advice from an obstetrician about your baby’s condition. Promptly contact your doctor if your baby displays any signs or symptoms of sepsis.

Looking for more information about laboratory, radiology, and other examination results? Click here!