Comparison between transient and permanent congenital hypothyroidism on a thyroid function test after re-evaluation

Area of Science:

• Pediatric Endocrinology
• Neonatal Screening
• Thyroid Function Tests

Background:

• Congenital hypothyroidism (CH) is diagnosed via neonatal screening and treated neonatally.
• Transient CH (TCH) is a subset of CH requiring re-evaluation to discontinue treatment.
• Identifying optimal strategies for levothyroxine discontinuation in TCH is crucial.

Purpose of the Study:

• To determine the best method for discontinuing levothyroxine in patients with CH.
• To analyze trends in thyroid function tests (TFTs) following levothyroxine discontinuation.
• To differentiate between transient and permanent CH (PCH).

Main Methods:

• Retrospective review of 388 patients diagnosed with CH.
• Classification of patients into permanent CH (PCH) and TCH groups (83 patients total).
• Comparison of clinical parameters and TFT trends to predict TCH.

Main Results:

• Higher thyroid-stimulating hormone (TSH) levels observed in the PCH group post-discontinuation and over 1-3 years (P<0.01).
• Higher free thyroxine (fT4) levels observed in the TCH group post-discontinuation and over 1-3 years (P<0.01).
• An average TSH >9.05 μIU/mL over 3 years accurately predicted PCH with 100% sensitivity and specificity.

Conclusions:

• Levothyroxine can be discontinued when TSH is between 10–20 μIU/mL, with subsequent results around 10 μIU/mL or decreasing.
• Thyroid function test trends, especially TSH, are key indicators for managing TCH re-evaluation.
• A 3-year average TSH cutoff >9.05 μIU/mL reliably identifies PCH.