Establishing reference interval for thyroid-stimulating hormone in children below two-year ages in Pakistani...

Area of Science:

• Pediatric Endocrinology
• Clinical Chemistry
• Laboratory Medicine

Background:

• Thyroid-stimulating hormone (TSH) and free thyroxine (FT4) reference intervals (RIs) are critical for diagnosing thyroid dysfunction.
• Existing RIs are assay and population-specific, with a lack of age-specific data for children under two years.
• Establishing accurate RIs is essential for appropriate clinical management of pediatric thyroid disorders.

Purpose of the Study:

• To determine assay-specific reference intervals for serum TSH and FT4 concentrations.
• To focus on healthy children aged 1 to 24 months, a population with limited existing data.
• To adhere to CLSI C28-A3 guidelines for establishing clinical laboratory standards.

Main Methods:

• Prospective, cross-sectional study design.
• Inclusion of 131 healthy children aged 1-24 months, excluding those with recent illness or thyroid disease history.
• Serum TSH and FT4 measurement using ADVIA Centaur chemiluminescence immunoassay and non-parametric statistical analysis for RI determination.

Main Results:

• Established reference interval for TSH: 0.73-4.94 μIU/mL.
• Established reference interval for FT4: 0.81-1.51 ng/dL.
• Data distribution was non-normal, necessitating a non-parametric approach for RI calculation.

Conclusions:

• Successfully established assay-specific reference intervals for TSH and FT4 in the 1-24 month age group.
• The derived RIs were observed to be slightly lower compared to those from different platforms and populations.
• These findings contribute valuable, localized data for the accurate assessment of thyroid function in young children.