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Physiology · Endocrinology: congenital hypothyroidism
Sample itemA 3-week-old baby has prolonged jaundice, a large tongue, constipation and a hoarse cry. Why is early detection by newborn screening important?
Original practice item, not a recalled exam question. Nothing here is recorded.
The answer and the reasoning
C. Thyroid hormone is needed for brain development in the first years of life
Thyroid hormone drives myelination and neuronal maturation. Untreated congenital hypothyroidism leads to irreversible intellectual disability, so levothyroxine must start in the first weeks.
Option by option
A. Thyroid hormone controls closure of the ductus arteriosus
Ductal closure is related to oxygen and prostaglandins.
B. Thyroid hormone is needed for lung maturation
Lung maturation depends on cortisol and not mainly on thyroid hormone.
C. Thyroid hormone is needed for brain development in the first years of life (correct)
Correct. Early thyroxine prevents permanent neurodevelopmental damage.
D. The condition resolves without treatment
It is permanent in most cases and needs treatment.
Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.
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