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Table 8 Findings in diagnostic studies undertaken to identify the underlying etiology of congenital hypothyroidism

From: Congenital hypothyroidism

Defect

Radionuclide image

Ultrasonography

Serum thyroglobulin

Maternal TRB-Ab

Aplasia

No uptake

Absent gland

Low

Negative

Hypoplasia

↓ uptake

Small, eutopic

Intermediate

Negative

Ectopia

↓ uptake, ectopic

Ectopic gland (hypoplastic)

Intermediate

Negative

TSHβ mutations

No uptake

Eutopic gland (hypoplastic)

Intermediate

Negative

TSH receptor inactivating mutation

↓ uptake

Eutopic gland

Intermediate-high

Negative

Trapping error

↓ or no uptake

Eutopic gland

Low-intermediate

Negative

Beyond trapping error

↑ uptake

Eutopic, large gland

High Exception: Tg gene mutations

Negative

Maternal TRB-Ab

↓ or no uptake

Eutopic gland

Low-intermediate

Positive