[Tc]-99m thyroid scintigraphy in congenital hypothyroidism screening program.

Area of Science:

• Pediatric Endocrinology
• Nuclear Medicine
• Neonatal Screening

Background:

• Congenital hypothyroidism (CH) etiology impacts disease severity and treatment. Athyroid cases necessitate higher doses and close monitoring, especially in neonates.
• Early detection of thyroid agenesis is crucial for timely intervention and improved outcomes in infants with CH.

Purpose of the Study:

• To evaluate thyroid scintigraphy (TS) findings in infants diagnosed with CH.
• To determine the relationship between serum TSH and T4 levels and thyroid agenesis.
• To identify factors predictive of thyroid agenesis prior to initiating treatment.

Main Methods:

• A screening program for CH was conducted from August 2002 to April 2005.
• Newborns were screened for CH using serum T4 and TSH levels. Suspected cases underwent repeat testing and clinical evaluation.
• Technetium-99m thyroid scintigraphy (Tc-99m TS) was performed on infants with suspected CH before thyroxine replacement therapy.

Main Results:

• Of 93,381 screened newborns, 262 (1:357 live births) had CH. The overall incidence was 1:357, with a female-to-male ratio of 1.4:1.
• Thyroid scans were performed on 116 infants; 33 (28.4%) were athyrotic, 7 (6%) had ectopic thyroid, and 76 (65.6%) had normal scans.
• Infants with athyrosis showed significantly higher TSH levels compared to those with ectopic or normal thyroid scans (P < 0.0001).

Conclusions:

• Tc-99m TS is a valuable diagnostic tool for the initial assessment of suspected CH.
• The correlation between TS results and blood TSH levels aids in identifying thyroid agenesis.
• Close monitoring and appropriate management are essential for infants with severe hormonal alterations and suspected thyroid agenesis.