Repercussions of TSH cutoff level to 6 mU/l in neonatal screening for congenital hypothyroidism in Santa Catarina: preliminary results

Program: Abstracts - Orals, Featured Poster Presentations, and Posters
Session: SAT 622-631-Pediatric Endocrinology: Thyroid
Saturday, June 15, 2013: 1:45 PM-3:45 PM
Expo Halls ABC (Moscone Center)

Poster Board SAT-628
Marilza Leal Nascimento*1, Patricia Dornbusch2, Masanao Ohira3, Genoir Simoni4, Edson Cechinel5, Rose Marie Linhares5 and Paulo Cesar Silva5
1Joana de Gusmão Childrens Hospital, 2UFSC, Faculty of Medicine, Florianopolis, Brazil, 3Santa Catarina Federal University, Florianopolis, Brazil, 4Joana de Gusmao Childrens Hospital, 5Joana de Gusmao Childrens Hospital, Florianopolis, Brazil
OBJECTIVE: This study assessed the implications of changing the cutoff level of TSH from 10 to 6 mU/l.

METHODS: The study population was constituted of 74.123 children screened for Congenital Hypothyroidism by the National Screening Program in Santa Catarina, southern Brazil, from March 2011 to February 2012. The TSH cutoff level was 6 mU/l. If TSH was between 6 and 10 mU/l a second sample was collected. If TSH > 6 mU/l in this second sample, the child was sent for medical evaluation.

RESULTS: 435 children were recalled for presenting TSH between 6 and 10 mU/l in the first sampling, 28 remained TSH > 6mU/l in the second sampling. Among these, 15 were diagnosed as dyshormonogenesis or transient, two ectopic thyroid and one thyroid hypoplasia.

DISCUSSION: One study in the UK lowered the TSH cutoff level to 6 mU/l. From 67 children who had TSH between 6.1 and 10 mU/l in the initial test, four of them continued with TSH greater than 6 mU/l in the second sample and one of them with TSH > 10 mU/l. Two were diagnosed with Congenital Hypothyroidism (CH) and treated with levothyroxine. Another study at Hospital das Clínicas da Faculdade de Medicina de Ribeirão Preto, in Sao Paulo, southeast Brazil, lowered the cutoff level of TSH to 5 mU/l. Children with TSH between 5 and 10 mU/l were considered borderline and a new sample was requested. If this sample presented values of TSH > 5 mU/l, the child was called for determination of serum TSH. If serum TSH was < 4 mU/l, it was considered normal. If presented values of TSH> 4 mU/l, the child would be assessed and monitored clinically. Among the 76,800 children evaluated, 7 were diagnosed with hypothyroidism and received treatment. In our study, the adoption of the cutoff level of TSH in 6 mU/l has resulted in an increase in number of recalls and false positives compared to the previously adopted cutoff level of 10 mU/l. However, 15 patients were diagnosed with transient congenital hypothyroidism or dyshormonogenesis, two patients with ectopic thyroid and one with thyroid hypoplasia.

CONCLUSION: Reduce the TSH cutoff level from 10 to 6 mU/l, reduces the number of false negatives, increasing the test sensitivity, but increases the number of false positives and recalls. Despite these negative aspects, reducing the cutoff level allows the diagnosis of thyroid abnormalities which require treatment, justifying its adoption.

Nothing to Disclose: MLN, PD, MO, GS, EC, RML, PCS

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