What is the flow diagram for the evaluation and management of congenital hypothyroidism in newborns?

Flow Diagram for Congenital Hypothyroidism

Follow this algorithmic approach based on the 2014 European Society for Paediatric Endocrinology consensus guidelines to ensure optimal neurodevelopmental outcomes through early detection and treatment 1.

Step 1: Newborn Screening

Initial screening specimen:

• Collect dried blood spot (DBS) for TSH measurement
• Standard timing: 2-5 days of life
• High-risk populations requiring second screening at ~2 weeks: preterm infants (<37 weeks), low/very low birth weight, NICU admissions, specimens collected <24 hours of life, multiple births (especially same-sex twins) 1

Step 2: Screening Result Interpretation & Immediate Action

If DBS TSH ≥40 mU/L whole blood:

• Start treatment immediately after obtaining venous sample for baseline TSH and FT4
• Do NOT wait for venous results unless available same day 1
• Contact family urgently via experienced personnel (screening lab or pediatric endocrine team) 1
• See infant same day or next day at latest 1

If DBS TSH <40 mU/L whole blood:

• Obtain venous TSH and FT4
• May wait 1-2 days for venous results before treatment 1

Step 3: Venous Confirmation & Treatment Decision

Immediate treatment indicated if:

• Venous FT4 below age norms (regardless of TSH) 1
• Venous TSH ≥20 mU/L (even if FT4 normal) 1

Borderline zone (TSH 6-20 mU/L with normal FT4 in well baby >21 days):

• Perform diagnostic imaging (thyroid ultrasound and/or scintigraphy) 1
• Two management options (discuss with family):
  • Start L-T4 immediately, retest off treatment later, OR
  • Retest in 2 weeks without treatment 1
• If TSH remains elevated >3-4 weeks, initiate treatment 1

TSH <6 mU/L with normal FT4:

• No treatment needed
• Consider repeat screening if high-risk population

Step 4: Initial Clinical Assessment (Parallel to Treatment Initiation)

Examine carefully for:

• Cardiac malformations (priority screening) 1
• Dysmorphic features
• Large posterior fontanelle, macroglossia, umbilical hernia
• Prolonged jaundice, constipation, lethargy, hypothermia 2

Step 5: Diagnostic Imaging (Do NOT Delay Treatment)

Perform within first weeks but never postpone therapy:

• Thyroid ultrasound and/or radioisotope scintigraphy (with/without perchlorate discharge test) 1
• Optional: Knee X-ray for femoral/tibial epiphyses (assesses severity of intrauterine hypothyroidism) 1

Step 6: Treatment Initiation

Levothyroxine dosing:

• 10-15 mcg/kg/day orally 3, 2
• Demonstrate administration to parents (clinician or pharmacist) 1
• Target: FT4 in upper half of age-specific range, TSH in normal range 1

Step 7: Monitoring Schedule

Intensive early monitoring is critical for neurodevelopment:

First follow-up: 1-2 weeks after starting L-T4 1

• Measure TSH and FT4 ≥4 hours post-dose 1

Until TSH normalizes: Every 2 weeks 1

Age 0-12 months: Every 1-3 months after TSH normalization 1

Age 1-3 years: Every 2-4 months 1

• This is the critical neurodevelopmental window

After age 3 years: Every 3-12 months until growth complete 1

More frequent if: poor compliance or abnormal values 1

Step 8: Re-evaluation for Permanent vs. Transient CH

Timing: After age 3 years (when neurodevelopmental risk period ends)

Indicated when:

• No diagnostic imaging performed in infancy
• Infant was preterm/sick at diagnosis
• Mild TSH elevation at diagnosis 1

Method:

• Phase out L-T4 over 4-6 weeks, then retest with imaging 1, OR
• Reduce L-T4 dose by 30% for 2-3 weeks; if TSH rises ≥10 mU/L, CH confirmed 1

Critical Pitfalls to Avoid

⚠️ Never delay treatment for imaging results 1

⚠️ Do not reduce L-T4 based on single elevated FT4 1

⚠️ Remember: Normal newborn screening does not exclude acquired hypothyroidism - maintain clinical vigilance 3, 2

⚠️ Special populations need second screening - preterm, VLBW, NICU, early collection, twins 1

⚠️ TSH screening misses central hypothyroidism - consider if low FT4 with inappropriately normal/low TSH 3