PLAB 1 Paediatrics 2

Question 1

A newborn infant is found to have bilateral undescended testes and ambiguous genitalia. What is the most important initial investigation?

Accepted Answer

Urgent serum 17-hydroxyprogesterone level to exclude congenital adrenal hyperplasia (CAH)

Answer

Bilateral undescended testes with ambiguous genitalia requires urgent investigation for congenital adrenal hyperplasia (CAH), which can cause a life-threatening salt-wasting crisis. Serum 17-hydroxyprogesterone is the key initial test. Electrolytes should also be checked urgently as hyponatraemia and hyperkalaemia can be fatal.

Question 2

A 7-year-old child presents with periorbital oedema, generalised oedema, and frothy urine. Urine dipstick shows 4+ protein. Blood tests show low serum albumin (15 g/L) and high cholesterol. What is the most likely diagnosis?

Accepted Answer

Nephrotic syndrome

Answer

The triad of nephrotic syndrome is heavy proteinuria (>3.5 g/day), hypoalbuminaemia, and oedema. Hypercholesterolaemia is also characteristic. In children, the most common cause is minimal change disease. First-line treatment is oral corticosteroids (prednisolone), with >90% responding.

Question 3

A 10-year-old child presents 2 weeks after a sore throat with haematuria, facial oedema, hypertension, and dark ('cola-coloured') urine. What is the most likely diagnosis?

Accepted Answer

Post-streptococcal glomerulonephritis

Answer

Post-streptococcal glomerulonephritis typically presents 1-3 weeks after a Group A streptococcal pharyngitis or skin infection. Features include haematuria (cola-coloured urine), hypertension, oedema, and reduced urine output. Anti-streptolysin O (ASO) titre is elevated and complement C3 is low.

Question 4

A 3-year-old child presents to A&E with a non-blanching purpuric rash, fever, and altered consciousness. What is the most important immediate action?

Accepted Answer

Administer IV/IM benzylpenicillin or ceftriaxone immediately without waiting for investigation results

Answer

A non-blanching purpuric rash with fever and altered consciousness strongly suggests meningococcal septicaemia. This is a medical emergency — antibiotics (IV ceftriaxone or benzylpenicillin) must be given immediately. Do not delay treatment for investigations. Blood cultures can be taken alongside but must not delay antibiotics.

Question 5

According to UK guidelines, at what age should a child be referred for further assessment if they are not walking independently?

Accepted Answer

18 months

Answer

While most children walk independently between 12-15 months, the threshold for referral for developmental assessment is 18 months if a child is not walking independently. This may indicate developmental delay, neurological conditions (e.g., cerebral palsy), or other causes requiring investigation.

PLAB 1 Practice Test

PLAB 1 Practice Test

PLAB 1 Paediatrics 2