Pertechnetate scintigraphy in primary congenital hypothyroidism

Area of Science:

• Pediatric Endocrinology
• Nuclear Medicine
• Neonatal Screening

Background:

• Primary congenital hypothyroidism (PCH) is detected via newborn screening, with thyroxine replacement therapy (TRT) initiated to prevent developmental issues.
• A significant portion of neonates with abnormal screening results have transient PCH, necessitating accurate etiological diagnosis.
• Pinhole thyroid imaging with 99mTc-pertechnetate (TcPT) is employed to determine the cause of PCH and assess transience.

Purpose of the Study:

• To evaluate the role of TcPT scintigraphy in diagnosing the etiology of PCH in neonates.
• To determine the utility of TcPT imaging in identifying transient PCH and guiding treatment discontinuation.
• To correlate scintigraphic findings with clinical outcomes in neonates with PCH.

Main Methods:

• Retrospective review of data from 103 neonates diagnosed with PCH who underwent TcPT scintigraphy between 1970 and 1996.
• Classification of patients based on four distinct thyroid scintigram patterns: normal, hypoplasia-ectopia, nonvisualization, and dyshormonogenesis.
• Correlation of scintigraphic results with clinical follow-up and treatment outcomes, including TRT discontinuation.

Main Results:

• Four scintigraphic patterns were identified, aiding in patient classification and management.
• Hypoplasia-ectopia (32 patients) and agenesis (32 of 35 nonvisualization cases) typically required lifelong TRT.
• Dyshormonogenesis (29 patients) included both permanent (25) and transient (4) forms, with familial occurrence noted in 12 patients across five families.

Conclusions:

• TcPT thyroid scintigraphy provides a specific diagnosis for PCH in neonates.
• The imaging is crucial for identifying patients eligible for re-evaluation to discontinue TRT in transient PCH cases.
• Dyshormonogenesis is often familial, highlighting the need for genetic counseling, and TcPT imaging is cost-effective.