[Normal 131iodine uptake values at 2 and 24 hours].

Area of Science:

• Endocrinology
• Nuclear Medicine

Background:

• Radiolabeled iodine uptake is a critical diagnostic tool for various thyroid conditions.
• Establishing baseline normal values is essential for accurate interpretation of thyroid function tests.

Purpose of the Study:

• To determine the normal range of 131 Iodine thyroid uptake in a healthy adult population.
• To investigate the influence of demographic factors like age and gender on iodine uptake values.

Main Methods:

• 105 healthy volunteers (52 males, 53 females) underwent clinical evaluation and completed a health questionnaire.
• Serum TSH and anti-thyroperoxidase antibodies were measured to exclude endocrine disorders.
• Radioactive iodine (131I) uptake was measured at 2 and 24 hours using Thyrad equipment after oral administration of a 5-10 microCi dose.

Main Results:

• Mean global 131I uptake was 5.5% ± 1.8% at 2 hours and 16.2% ± 4.8% at 24 hours.
• Females exhibited significantly higher uptake than males at both 2 hours (6.0% vs. 4.9%, p<0.02) and 24 hours (17.3% vs. 15.0%, p=0.01).
• Volunteers over 40 years old showed lower uptake compared to younger individuals at 2 hours (5.0% vs. 6.0%, p<0.02) and 24 hours (14.9% vs. 17.6%, p<0.01).

Conclusions:

• Normal thyroid iodine uptake values in adults are significantly influenced by both gender and age.
• Higher uptake in females and a slight decrease in uptake after age 40 are important considerations for clinical interpretation.
• These findings provide updated reference ranges for radioactive iodine uptake, aiding in the diagnosis and management of thyroid diseases.