Newborn bloodspot screening for inherited metabolic disease and follow-up — formative SAQs

SAQ 1 — Critical TSH in a well neonate (20 marks, ~15 minutes)

A 6-day-old term infant is at home and feeding well. The bloodspot laboratory reports a critical elevated TSH. Parents are anxious and ask whether review can wait until next week because “he looks perfect.” ^[3]

Questions

1. Define screening versus diagnosis in this setting and state the result-state urgency. (4 marks) ^[14]
2. Outline your same-day management steps, including confirmatory testing and treatment principles for congenital hypothyroidism. (6 marks) ^[3]
3. Explain the pathophysiology that makes well appearance an unsafe reassurance. (5 marks) ^[3]
4. Write the safety-net and handover content you would document. (5 marks) ^[17]

Model answer (must-hit)

1. Screen positive/presumptive positive is not a final diagnosis; it requires confirmatory free T4/TSH and a defined pathway. Critical markers need same-day contact, not routine delay. ^{[3] [14]}
2. Phone family; arrange urgent clinical review and confirmatory thyroid function tests; start levothyroxine on the current protocolised pathway with endocrine follow-up; do not wait for developmental signs. State you use local dosing protocol rather than inventing figures. ^[3]
3. After birth, maternal/placental thyroid support falls. Low thyroxine injures the developing brain while growth and feeding may still look acceptable. ^[3]
4. Document result state, tests done, treatment started or timed, who owns follow-up, contact numbers, and advice for poor feeding, lethargy or jaundice concerns. ^[17]