Neonatal screening

Question 1

Aims of neonatal screening

Answer 1

To detect disorders before symptoms first appear to allow treatment to start early, giving the best prognosis

Question 2

Characteristics of screened diseases

Answer 2

• Important health problem
• Natural history well understood
• Has a latent phase
• Has available treatment
• Has a suitable screening test
• Cost-effective

Question 3

Established UK screens

Answer 3

A typical neonatal screening test is a heel-prick, carried out at 6-10 days of age

• Congenital hypothyroidism
• Phenylketonuria
• Medium chain acyl-CoA dehydrogenase deficiency

Question 4

Congenital hypothyroidism

Answer 4

A deficiency in thyroid hormones which can lead to cretinism

Causes = thyroid dysgenesis, pituitary disease

Treatment = daily thyroxine, given within 14 days of birth

Question 5

Phenylketonuria

Answer 5

A defect in phenylalanine metabolism, leading to tyrosine deficiency which affects neural development

Causes = recessive inheritance, IV feeding, liver disease, biopterin defects

Treatment = dietary restriction of phenylalanine, substitute amino acid mixtures, given with 21 days of birth

Question 6

Medium chain acyl-CoA dehydrogenase deficiency

Answer 6

An enzyme deficiency leading to incomplete catabolism of fatty acids

Can lead to a build-up of toxic fatty acids

Clinical features = sudden infant death syndrome, acute attacks of drowsiness

Treatment = energy intake maintained