Screening for congenital hypothyroidism: the value of retesting after four weeks in neonates with low and very low birth weight

Jagiellonian University, Cracovia, Lesser Poland Voivodeship, Poland
Journal of Medical Screening (Impact Factor: 2.72). 12/2005; 12(4):166-9. DOI: 10.1258/096914105775220697
Source: PubMed

ABSTRACT Thyroid-stimulating hormone (TSH), normally a reliable screening test for congenital hypothyroidism (CH), may fail to detect cases among infants who have low and very low birth weight. The purpose of this study was to identify neonates with false-negative screening results.
A province in Poland in which 3,854 neonates had body weight <or=2,500 g, between 1999 and 2001.
TSH levels in blood on filter paper were measured in all neonates between the third and sixth days after birth, but were repeated in low and very low birth weight infants after four weeks of age.
The repeat test showed TSH levels >or= 10 mIU/L in 19 of the 3,854 low birth weight neonates. The final diagnosis in these neonates was permanent CH in two, transient CH in five, possible compensated CH in six and transient high TSH in six. Of the 19, 16 (84%) required iodine and/or thyroxine replacement therapy.
In neonates with low and very low birth weight, normal TSH levels measured between the third and sixth day of life do not exclude thyroid dysfunction, but a repeat TSH measurement after the fourth week of life identifies the false-negative results. In our data, the prevalence of primary and secondary hypothyroidism (both permanent and transient) was about 0.5%.


Available from: Malgorzata Kumorowicz-Czoch, Nov 20, 2014
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Congenital hypothyroidism (CHT) is one of the most common congenital endocrinal disorders. The prevalence of CHT is estimated about 1 in 3,000 newborns. The prevalence, etiology and associated disorders of abnormal thyroid screening tests are reported in different ranges. In this study, we assessed the pre-term newborns for CHT and associated factors that influence thyroid function. One hundred newborns with the gestational age fewer than 35 weeks were investigated. Baseline serum thyroid stimulating hormone (TSH) and free thyroxin (FT4) levels were measured during the first 5 days of life and were repeated during the first 5 weeks. We analyzed the effects of demographic factors and the presence of respiratory distress syndrome on the alteration of thyroid function tests during the first 5 weeks of life. The mean gestational age (GA) at delivery was 32.35í1.97 (range 28 to 35) weeks. CHT was observed in 13(13%) preterm infants. GA was the only factor which affect the FT4 changes over the two weeks follow-up (P < 0.001, b: -2.783, Power: 70.2%) although the differences between baseline and follow-up amount of TSH were not significantly influenced by GA (P = 0.062, power: 46%). However, the adjusted TSH and FT4 serum level changes during follow-up were significantly different between two groups (between CHT and normal, P = 0.006, 0.000, respectively). It seems that thyroid function tests should be repeated in preterm infants, especially for patients with lower gestational age, to confirm the diagnosis of CHT. Also, CHT should be considered among the newborns that are affected by RDS.
    International journal of preventive medicine 11/2013; 4(11):1271-1276.
  • [Show abstract] [Hide abstract]
    ABSTRACT: To compare 2 screening protocols performed concurrently in Minnesota: (1) liquid chromatography tandem mass spectrometry steroid profiling as a second-tier test on positive fluoroimmunoassay (FIA) results; and (2) low-birthweight 3-screen protocol (FIA tests at <48 hours, 2 weeks, 4 weeks) on all infants <1800 g, regardless of result. Population-based study of all <1800 g infants (n = 8739) born in Minnesota from 2004-2010 comparing newborn screening performance metrics of 2-tier (FIA + liquid chromatography tandem mass spectrometry) protocol (2004-2010) vs 1-tier (FIA) low-birthweight 3-screen protocol (2006-2010). False positive (FP) rates were calculated per infant's final confirmatory result. Protocol results used in different time periods (2004-2005 vs 2006-2010) were compared by 2-sample tests of proportions; results of both protocols for 2006-2010 were compared by McNemar test. First-tier testing of final dried blood spot result (n = 6625) of the low-birthweight 3-screen protocol during 2006-2010 reduced the FP rate more than 5-fold (P < .0001) compared with 2-tier testing of a single dried blood spot (n = 2114) from 2004-2005. In comparing results (n = 6625) of both protocols from 2006-2010, first-tier testing of final dried blood spot accounted for 23% of FPs; second-tier testing of the first dried blood spot accounted for 77%, yielding significantly more FP results (McNemar test, P < .0001). Timing of dried blood spot collection rather than assay used played a more important role in reducing FP results of congenital adrenal hyperplasia newborn screening in low birthweight infants.
    The Journal of pediatrics 02/2014; 164(5). DOI:10.1016/j.jpeds.2014.01.038 · 3.74 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Objective To determine the evolution of congenital hypothyroidism in preterms and the clinical features of permanent forms. Study design We retrospectively evaluated 24 preterm children detected by newborn screening for congenital hypothyroidism: first screening with blood-thyroid stimulating hormone cutoff ≥10 mU/L and second screening with blood-thyroid stimulating hormone cutoff ≥5 mU/L. After the age of 2 years, patients with eutopic thyroid had diagnostic reevaluations, including thyroid function testing and thyroid ultrasonography after L-thyroxine therapy withdrawal. Results The first screening identified 21.7% of patients with thyroid stimulating hormone elevation, and the second screening identified 73.9% of patients. One patient (4.4%) was identified with a third screening test; 21 patients had an eutopic thyroid and 3 patients a thyroid dysgenesis. At reevaluation, 5 patients (23.8%) showed permanent hypothyroidism (serum-thyroid stimulating hormone [s-TSH] >10 mU/L) resulting in the need to reintroduce therapy, 5 patients (23.8%) showed persistent hyperthyrotropinemia (s-TSH 5-10 mU/L), and 11 infants (52.4%) transient hypothyroidism (s-TSH <5 mU/L). The main clinical features of patients affected by permanent hypothyroidism were 1 case of assisted reproduction, 2 twins, 2 small for gestational age, 1 maternal thyroiditis, and 2 patients with malformations/syndromes. Conclusions Premature birth is a significant risk for congenital hypothyroidism with eutopic thyroid. In preterm infants, the evolution of congenital hypothyroidism remains difficult to predict. Our data emphasizes the high incidence of transient hypothyroidism in preterm infants, and the importance of diagnostic reevaluation to determine the definitive diagnosis.
    The Journal of pediatrics 06/2014; 164(6). DOI:10.1016/j.jpeds.2013.12.048 · 3.74 Impact Factor