Hearing impairment screening

Neonatal ScreeningHasanuddinJot Jin YinMegat Mohd AzmanWhy Do Newborn Screening?Early detection & early treatment of newborn screening disorders:Lessens severity of complicationsImproves quality of life

Lack of early detection & treatment can lead to:Severe mental retardationInadequate growth & developmentDeath

Neonatal Screening in MalaysiaScreening tests done at birth, for all babies:Glucose-6-phospate dehydrogenase (G6PD) deficiency Congenital hypothyroidism

Screening test done in high risk neonates:Hearing impairment screeningEye screening3Glucose-6-phosphate dehydrogenase(G6PD) deficiency4Introduction Commonest red cell enzymopathy

Affecting over 100 million people worldwide.

It has a high prevalence (1020%) in individuals originating from central Africa, the Mediterranean, the Middle East and the Far East. Function G6PD is the rate-limiting enzyme in the pentose phosphate pathway and is essential for preventing oxidative damage to red cells.

Red cells lacking G6PD are susceptible to oxidant-induced haemolysis

G6PD deficiency is X-linked and therefore predominantly affects males.Causes

Clinical feature

Diagnosis Diagnosis/Screening:Cord blood collection for quantitative enzyme assayEnzymatic colorimetric assay for the quantitative determination of G6PD deficiency6.4 U/gHb- Any neonate with an activity below this value was diagnosed as G6PD deficientNot 100% sensitive, may miss some casesLaboratory findings: Peripheral blood smear shows fragmented bite cells and polychromasia, spherocytosis, Heinz bodiesA "direct antiglobulin test" (Coombs' test) this should be negative, as hemolysis in G6PD is not immune-mediatedHeinz bodies and bite cells

Management The most important measure is prevention avoidance of the drugs and foods that cause hemolysis. Vaccination against some common pathogens (e.g. hepatitis A and hepatitis B) may prevent infection-induced attacks.In the acute phase of hemolysis, blood transfusions might be necessary, or even dialysis in acute kidney failure.Some patients may benefit from removal of the spleen (splenectomy),as this is an important site of red cell destruction. Folic acid should be used in any disorder featuring a high red cell turnoverCongenital hypothyroidismCongenital hypothyroidismCongenital hypothyroidism is a deficiency of the circulating thyroid hormone at birthIt can occur because of an anatomic defect in the gland, an inborn error of thyroid metabolism, or iodine deficiency.The incidence of congenital hypothyroidism, as detected through newborn screening, is approximately 1 per 4000 birthsTwinstwins are approximately 12 times as likely to have congenital hypothyroidism as singletons.female-to-male ratio of a 2:1.

Signs and symptomsSymptomsDecreased activityLarge anterior fontanellePoor feeding and weight gainSmall stature or poor growthJaundiceDecreased stooling or constipationHypotoniaHoarse cry SignsCoarse facial featuresMacroglossiaLarge fontanellesUmbilical herniaMottled, cool, and dry skinDevelopmental delayPallorMyxedemaGoiter

DIAGNOSIS

Cord blood sample test for TSH.If high TSH check T4, if low TSH check for other pituitary defects. Combination of low or low-normal serum total T4 levels and a serum TSH within the reference range suggests thyroid-binding globulin (TBG) deficiencyOther investigations: radioactive iodine uptake study, ultrasound, antithyroid antibodiesThyroid scanning- (using technetium-99m or iodine-123), the absence of radionuclide uptake suggests thyroid receptor blocking antibodies, - can also demonstrate the presence of an ectopic thyroid, such as a lingual or sublingual gland

MANAGEMENTThyroid replacement: thyroxine 10-15g/kg/day Infants with very low or undetectable T4, give 50 g daily. Free T4 levels should be maintained at all times in the upper normal range during the first 3 years of life. Follow up: TSH and Free T4, every month during infancy, every 3 months from age 1-3, and 6 monthly thereafter.

MANAGEMENTTIMING- should begin after diagnosisDURATION- life long except in children suspected of having transient hypothyroidism where re- evaluation is done at 3 years of agePREPARATION No approved liquid preparationOnly L- thyroxin in tablet should be use crushed and mixed with breast milk, formula, water and fed the infant but to not soy contain or iron contain in which iron will reduce absorption of T4. Follow-up Monitor growth parameters and developmental assessment.

High Risk ScreeningHearing impairment screeningNeonates with risk factors for hearing loss are screened at week 4-5 of life.Hearing test for neonates:Auditory brainstem response (ABR)- assessment of hearing thresholds and the functional status of the auditory neural pathwayOtoacoustic emissions (OAE) test - to determine cochlear status, specifically hair cell function. Good prognosis (better language and social development) if treatment initiated