White Thyroid Scintigraphy

Area of Science:

• Endocrinology
• Nuclear Medicine
• Pediatrics

Background:

• White thyroid scintigraphy signifies minimal or absent radiotracer uptake in the thyroid gland.
• Primary causes include iodine overload, thyroiditis, and congenital hypothyroidism, a major cause of preventable intellectual disability.
• Thyroid scintigraphy is crucial for diagnosing the etiology of congenital hypothyroidism.

Purpose of the Study:

• To report a case of congenital hypothyroidism diagnosed via white thyroid scintigraphy in a newborn.
• To investigate the etiological factors contributing to the observed white thyroid scan.
• To emphasize the diagnostic utility of combining thyroid scintigraphy with cervical ultrasound.

Main Methods:

• A 22-day-old newborn diagnosed with congenital hypothyroidism was evaluated.
• Cervical ultrasound was performed to assess thyroid gland structure and vascularity.
• Technetium-99m (Tc 99m) thyroid scintigraphy was conducted to evaluate radiotracer uptake.

Main Results:

• Cervical ultrasound revealed a normal echostructure of the thyroid gland without lesions or vascular anomalies.
• Tc 99m thyroid scintigraphy demonstrated a complete lack of radiotracer uptake in the thyroid region, consistent with a white thyroid scan.
• The combination of a visible thyroid on ultrasound and a white scan suggested iodine transporter deficiency.

Conclusions:

• A white thyroid scan in a newborn with congenital hypothyroidism, alongside a normally positioned thyroid on ultrasound, strongly indicates iodine transporter deficiency.
• Mutations in the sodium/iodide symporter gene are the likely cause of this deficiency.
• This case underscores the importance of integrated diagnostic imaging in pinpointing the cause of congenital hypothyroidism.