Free thyroxine and thyroid-stimulating hormone reference intervals in very low birth weight infants at 3–6weeks of life with the Beckman Coulter Unicel DxI 800

AbstractThyroid dysfunction is more common in preterm and low birth weight infants, and may be missed if thyroid function test (TFT) is not repeated. Thus, we attempted to study the pattern of thyroid function among very low birth weight (VLBW) infants with birth weight less than 1,500 g by serial TFTs. Serum free thyroxine (FT4) and thyrotropin (thyroid-stimulating hormone [TSH]) levels of VLBW infants were tested on fifth to seventh days of life and repeated after 4 weeks of age. Based on serial FT4 and TSH results, abnormal TFT was classified into four groups—transient hypothyroxinemia of prematurity (THOP), transient hyperthyrotropinemia (THT), delayed TSH rise, and overt congenital hypothyroidism (CH). Stata 15.1 (Stata Corp, Texas, United States) was used for analysis. Ninety-six VLBW infants were enrolled with mean gestational age of 30.5 ± 2.7 weeks and median (interquartile range) birth weight of 1,200 (317) g. Out of 96 cases, 30 (31.2%) infants had abnormal TFT. Ten (10.4%) infants had THOP, 7 (7.3%) infants had THT, 11 (11.5%) infants had delayed TSH rise, and 2 (2.1%) infants had overt CH. There were no significant differences in demographic profile and clinical characteristics between neonates with normal and abnormal TFTs. Five infants required levothyroxine supplementation (two infants with overt CH and three infants with delayed TSH rise). VLBW neonates have higher incidence of CH and delayed rise of TSH in this study. In resource-limited settings, repeating TFTs at least once after 4 weeks of age may be suggested to identify delayed rise of TSH which may need intervention.

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

Journal of Medical Screening ◽

10.1258/096914105775220697 ◽

2005 ◽

Vol 12 (4) ◽

pp. 166-169 ◽

Cited By ~ 23

Author(s):

Dorota Tylek-Lemańska ◽

Małgorzata Kumorowicz-Kopiec ◽

Jerzy Starzyk

Keyword(s):

Birth Weight ◽

Low Birth Weight ◽

Congenital Hypothyroidism ◽

Very Low Birth Weight ◽

False Negative ◽

Thyroid Stimulating Hormone ◽

Low Birth Weight Infants ◽

The Third ◽

Secondary Hypothyroidism ◽

Tsh Levels

Objectives: 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. Setting: A province in Poland in which 3854 neonates had body weight ≤2500 g, between 1999 and 2001. Methods: 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. Results: The repeat test showed TSH levels ≥ 10 mIU/L in 19 of the 3854 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. Conclusions: 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%.

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Initial and delayed thyroid-stimulating hormone elevation in extremely low-birth-weight infants

BMC Pediatrics ◽

10.1186/s12887-019-1730-1 ◽

2019 ◽

Vol 19 (1) ◽

Cited By ~ 1

Author(s):

Shin Ae Yoon ◽

Yun Sil Chang ◽

So Yoon Ahn ◽

Se In Sung ◽

Won Soon Park

Keyword(s):

Birth Weight ◽

Low Birth Weight ◽

Perinatal Asphyxia ◽

Thyroid Stimulating Hormone ◽

Extremely Low Birth Weight ◽

Free T4 ◽

Low Birth Weight Infants ◽

Neurodevelopmental Outcomes ◽

Levothyroxine Replacement ◽

Stimulating Hormone

Abstract Background To determine the incidence, etiology, and outcomes of thyroid-stimulating hormone (TSH) elevation in extremely low-birth-weight infants (ELBWIs). Methods Newborn thyroid screening data of 584 ELBWIs (birth weight, < 1000 g; gestational age, ≥ 23 weeks) were retrospectively analyzed to identify initial (≤ 2 postnatal weeks) and delayed (> 2 weeks) TSH elevations. Growth and neurodevelopmental outcomes at 2 years’ corrected age (CA) were assessed according to levothyroxine replacement. Results Initial and delayed TSH elevations were detected at CAs of 27 and 30 weeks, respectively, with incidence rates of 0.9 and 7.2%, respectively. All infants with initial TSH elevations had perinatal asphyxia, and 95% of those with delayed TSH elevation were exposed to various stressors, including respiratory support, drugs, and surgery within 2 weeks before diagnosis of TSH elevation. Free thyroxine (T4) levels were simultaneously reduced in 80 and 57% of infants with initial and delayed TSH elevations, respectively. Both initial and delayed TSH elevations were transient, regardless of levothyroxine replacement. Infants receiving levothyroxine replacement therapy had significantly higher TSH elevations, significantly lower free T4 levels, and significantly reduced mortality, compared to untreated infants. However, levothyroxine replacement had no significant effect on long-term growth and neurodevelopmental outcomes. Conclusions The timing of insult superimposition on hypothalamic–pituitary–thyroid axis maturation is a major determinant of initial or delayed TSH elevation in ELBWIs. Levothyroxine replacement did not affect growth or neurodevelopmental outcomes in this population.

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Reference Intervals of Serum Procalcitonin Are Affected by Postnatal Age in Very Low Birth Weight Infants during the First 60 Days after Birth

Neonatology ◽

10.1159/000381330 ◽

2015 ◽

Vol 108 (1) ◽

pp. 60-64 ◽

Cited By ~ 6

Author(s):

Won-Ho Hahn ◽

Joon-Hwan Song ◽

Il-Sung Park ◽

Ho Kim ◽

Suyeon Park ◽

...

Keyword(s):

Birth Weight ◽

Low Birth Weight ◽

Very Low Birth Weight ◽

Reference Intervals ◽

Low Birth Weight Infants

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EPIDEMIOLOGIC CHARACTERISTICS AND RISK FACTORS FOR CONGENITAL HYPOTHYROIDISM FROM 2009 TO 2018 IN XIAMEN, CHINA

Endocrine Practice ◽

10.4158/ep-2019-0491 ◽

2020 ◽

Vol 26 (6) ◽

pp. 585-594 ◽

Cited By ~ 1

Author(s):

Jing Chen ◽

Shaowu Lin ◽

Guozhang Zeng ◽

Weixing Wang ◽

Zhenqiu Lin ◽

...

Keyword(s):

Birth Weight ◽

Low Birth Weight ◽

Newborn Screening ◽

Congenital Hypothyroidism ◽

Urban Areas ◽

Thyroid Stimulating Hormone ◽

Diagnosis And Treatment ◽

Low Birth Weight Infants ◽

Transient Congenital Hypothyroidism ◽

Stimulating Hormone

Objective: Early diagnosis and treatment of children with congenital hypothyroidism (CH) through newborn screening can effectively prevent delayed development. This study was designed to investigate the pathogenesis and factors that influence CH in urban areas of China between 2009 and 2018. Methods: A retrospective analysis of newborn screening data and diagnosis and treatment information for CH diagnosed in the information database of the neonatal disease screening center in one of China's five special economic zones from 2009 to 2018. Results: Of the 947,258 newborns screened between 2009 and 2018, 829 (406 girls) were diagnosed with CH at birth (1 diagnosis/1,136 births). Among the 608 cases of CH diagnosed at birth and re-evaluated at the age of 3 years, 487 were permanent congenital hypothyroidism (PCH, 1/1,429), and 121 were transient congenital hypothyroidism (TCH, 1/5,882). A total of 83.2% of infants with PCH (405/487) underwent thyroid imaging in the neonatal period, of which thyroid dysgenesis accounted for 28.64% (116/405) and functional defects accounted for 71.36% (289/405). The incidence of CH changed significantly in infants with initial serum thyroid-stimulating hormone concentrations of 41 to 100 mIU/L and ≥100 mIU/L, whereas the incidence of mild CH showed a slight increase. The incidence of CH was significantly higher in postterm infants (1/63) and low-birth-weight infants (1/370). Conclusion: In the past decade, the incidence of CH has increased, mainly due to the increase in the incidence of PCH and TCH. The incidence of mild CH has increased slightly. Postterm birth and low birth weight are important factors affecting the incidence of CH. Abbreviations: CH = congenital hypothyroidism; FT4 = free thyroxine; L-T4 = levothyroxine sodium; PCH = permanent congenital hypothyroidism; TCH = transient congenital hypothyroidism; TSH = thyroid-stimulating hormone; TT4 = total thyroxine

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