Newborn screening

Screening test is conducted in newborns to allow for early detection of any congenital disorders or abnormalities that are curable and can lead to irreversible impairment/damage if undiagnosed or untreated. The disorders are relatively common, so that it makes sense to screen newborn population for them. The screening is required by law regulations and is analysed in the reference laboratories.

Newborn screening begins with laboratory investigation of the umbilical cord blood, where we can analyse the following items:

  • blood gas
  • blood group and Coombs test (hemolytic disease of newborn)
  • serology
    RPR = rapid plasma reagin = screening test for syphilis (cardiolipin [phospholipid] incorporated in the membrane of Treponema Pallidum reacts with antibodies)
    TPHA= Treponema Pallidum hemagglutination = diagnostic test for syphilis (detects amount of anti-Treponema pallidum antibodies in the serum sample (umbilical cord) of a newborn)

For the more traditional newborn screening tests, the usual time window for screening is 48-72 hours of life and in certain cases requires rescreening (birth weight < 1500g, administration of dopamine, corticoids, fresh frozen plasma, red blood cell transfusion).

SCREENING TESTS

Congenital syphilis (lues)

  • Umbilical cord blood => see neonatal examination
  • The tests should be performed in every pregnancy as treatment of syphilis can prevent vertical transmission (mother => fetus)
  • In case of fetal infection, early postnatal treatment can prevent disease progression

Endocrinopathies

  • Capillary blood (heel)
  • Congenital hypothyroidism [CH] => blood is analyzed for thyroid-stimulating hormone [TSH; thyrotropin; thyrotropic hormone] and if elevated, thyroid hormones (T3 and T4) are analyzed from venous blood; treatment needs to be started as soon as possible in order to prevent severe brain damage
  • Congenital adrenal hyperplasia [CAH]) => blood is analyzed for 17-hydroxyprogesterone [17-OHP]

Cystic Fibrosis

  • Capillary blood (heel)
  • Blood is analyzed for immunoreactive trypsinogen [IRT] => in case of positivity, the blood is further investigated using molecular genetics methods for the most common cystic fibrosis gene mutations

Inborn Errors of Metabolism

  • Capillary blood (heel)
  • Amino acids disorders (phenylketonuria, hyperphenylalaninemia, maple syrup urine disease, glutaric acidemia I)
  • Fatty acid oxidation disorders (medium/long/very long chain acyl-CoA dehydrogenase deficiency)
  • Mitochondrial disorders (carnitine palmitoyltransferase I [CPT1; CoA:carnitine acyl transferase] and II deficiency)
  • Urea cycle disorders (carbamoyl phosphate synthetase I deficiency [CPS I deficiency]; citrullinemia; argininemia)
  • Organic aciduria (propionic, methylmalonic and isovaleric aciduria)

Developmental Dysplasia of the Hip

  • Congenital hip dislocation / Hip dysplasia
  • Condition where the “ball and socket” joint of the hip does not properly form in babies and young children
  • Clinical and Imaging (ultrasound) examination, including orthopaedic surgeon consultation (nursery or at 6 weeks and 3 months of age)

Congenital Cataract Screening

  • Clouding of the eye’s natural lens (lens opacity)
  • Ophthalmoscope examination to detect red reflex (normal finding) – in case of positive result (reduced or absent red reflex), detailed ophthalmologic examination

Congenital Hearing Loss

  • Detected by evoked otoacoustic emissions [OAE], automated auditory brainstem responses [AABR] or auditory evoked potentials [AEP]
  • Corrected by hearing aid (6 months) or cochlear implant (12 months, requires surgery)
  • If undiagnosed and untreated, hearing loss can have serious effects on many developmental areas, including language, social interactions, emotions, cognitive ability

Congenital Urinary Tract Disorders

  • Detected by postnatal ultrasound – detection prevents infectious complications (antibiotic prophylaxis)

Hemoglobinopathy

  • Sickle cell disease

REFERENCES

① Parish E, Tailor R, Gandhi R. How to conduct a newborn examination. BMJ. 2018;360:j5726. Published 2018 Jan 15. doi:10.1136/sbmj.j5726

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