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Congenital hypothyroidism.

Rastogi MV, LaFranchi SH - Orphanet J Rare Dis (2010)

Bottom Line: Common symptoms include decreased activity and increased sleep, feeding difficulty, constipation, and prolonged jaundice.Frequent laboratory monitoring in infancy is essential to ensure optimal neurocognitive outcome.Studies show that a lower neurocognitive outcome may occur in those infants started at a later age (> 30 days of age), on lower l-thyroxine doses than currently recommended, and in those infants with more severe hypothyroidism.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Pediatrics, Division of Endocrinology, Oregon Health & Science University, 707 SW Gaines Street, Portland, OR, USA.

ABSTRACT
Congenital hypothyroidism (CH) occurs in approximately 1:2,000 to 1:4,000 newborns. The clinical manifestations are often subtle or not present at birth. This likely is due to trans-placental passage of some maternal thyroid hormone, while many infants have some thyroid production of their own. Common symptoms include decreased activity and increased sleep, feeding difficulty, constipation, and prolonged jaundice. On examination, common signs include myxedematous facies, large fontanels, macroglossia, a distended abdomen with umbilical hernia, and hypotonia. CH is classified into permanent and transient forms, which in turn can be divided into primary, secondary, or peripheral etiologies. Thyroid dysgenesis accounts for 85% of permanent, primary CH, while inborn errors of thyroid hormone biosynthesis (dyshormonogeneses) account for 10-15% of cases. Secondary or central CH may occur with isolated TSH deficiency, but more commonly it is associated with congenital hypopitiutarism. Transient CH most commonly occurs in preterm infants born in areas of endemic iodine deficiency. In countries with newborn screening programs in place, infants with CH are diagnosed after detection by screening tests. The diagnosis should be confirmed by finding an elevated serum TSH and low T4 or free T4 level. Other diagnostic tests, such as thyroid radionuclide uptake and scan, thyroid sonography, or serum thyroglobulin determination may help pinpoint the underlying etiology, although treatment may be started without these tests. Levothyroxine is the treatment of choice; the recommended starting dose is 10 to 15 mcg/kg/day. The immediate goals of treatment are to rapidly raise the serum T4 above 130 nmol/L (10 ug/dL) and normalize serum TSH levels. Frequent laboratory monitoring in infancy is essential to ensure optimal neurocognitive outcome. Serum TSH and free T4 should be measured every 1-2 months in the first 6 months of life and every 3-4 months thereafter. In general, the prognosis of infants detected by screening and started on treatment early is excellent, with IQs similar to sibling or classmate controls. Studies show that a lower neurocognitive outcome may occur in those infants started at a later age (> 30 days of age), on lower l-thyroxine doses than currently recommended, and in those infants with more severe hypothyroidism.

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Related in: MedlinePlus

Technetium 99 m scan findings in congenital hypothyroidism. A-Technetium 99 m scan, showing a large gland (approximately twice normal size) in eutopic location, consistent with dyshormonogenesis. B-Technetium 99 m scan, showing uptake in ectopic location, i.e. ectopic gland. C-Minimal uptake, consistent with aplasia or severe hypoplasia.
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Figure 5: Technetium 99 m scan findings in congenital hypothyroidism. A-Technetium 99 m scan, showing a large gland (approximately twice normal size) in eutopic location, consistent with dyshormonogenesis. B-Technetium 99 m scan, showing uptake in ectopic location, i.e. ectopic gland. C-Minimal uptake, consistent with aplasia or severe hypoplasia.

Mentions: Either iodine-123 (I-123) or sodium pertechnetate 99 m (Tc99 m) are preferred for thyroid uptake and scan in neonates to minimize the radioactivity exposure; I-131 delivers a higher dose to the thyroid and total body and should not be used. Radionuclide uptake and scanning generally are the most accurate tests in defining some form of thyroid dysgenesis, e.g., an ectopic gland, thyroid hypoplasia (decreased uptake in a eutopic location), or thyroid aplasia [67] (Figure 5). Absence of radionuclide uptake should be confirmed by an ultrasonography. Absence of uptake can also be seen with TSHβ gene mutations, TSH receptor inactivating mutations, iodide trapping defects, and with maternal thyrotropin receptor blocking antibodies (TRB-Ab); thyroid ultrasonography and other studies, such as measurement of serum Tg or TRB-Ab will help to separate these etiologies from thyroid aplasia (see below).


Congenital hypothyroidism.

Rastogi MV, LaFranchi SH - Orphanet J Rare Dis (2010)

Technetium 99 m scan findings in congenital hypothyroidism. A-Technetium 99 m scan, showing a large gland (approximately twice normal size) in eutopic location, consistent with dyshormonogenesis. B-Technetium 99 m scan, showing uptake in ectopic location, i.e. ectopic gland. C-Minimal uptake, consistent with aplasia or severe hypoplasia.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2903524&req=5

Figure 5: Technetium 99 m scan findings in congenital hypothyroidism. A-Technetium 99 m scan, showing a large gland (approximately twice normal size) in eutopic location, consistent with dyshormonogenesis. B-Technetium 99 m scan, showing uptake in ectopic location, i.e. ectopic gland. C-Minimal uptake, consistent with aplasia or severe hypoplasia.
Mentions: Either iodine-123 (I-123) or sodium pertechnetate 99 m (Tc99 m) are preferred for thyroid uptake and scan in neonates to minimize the radioactivity exposure; I-131 delivers a higher dose to the thyroid and total body and should not be used. Radionuclide uptake and scanning generally are the most accurate tests in defining some form of thyroid dysgenesis, e.g., an ectopic gland, thyroid hypoplasia (decreased uptake in a eutopic location), or thyroid aplasia [67] (Figure 5). Absence of radionuclide uptake should be confirmed by an ultrasonography. Absence of uptake can also be seen with TSHβ gene mutations, TSH receptor inactivating mutations, iodide trapping defects, and with maternal thyrotropin receptor blocking antibodies (TRB-Ab); thyroid ultrasonography and other studies, such as measurement of serum Tg or TRB-Ab will help to separate these etiologies from thyroid aplasia (see below).

Bottom Line: Common symptoms include decreased activity and increased sleep, feeding difficulty, constipation, and prolonged jaundice.Frequent laboratory monitoring in infancy is essential to ensure optimal neurocognitive outcome.Studies show that a lower neurocognitive outcome may occur in those infants started at a later age (> 30 days of age), on lower l-thyroxine doses than currently recommended, and in those infants with more severe hypothyroidism.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Pediatrics, Division of Endocrinology, Oregon Health & Science University, 707 SW Gaines Street, Portland, OR, USA.

ABSTRACT
Congenital hypothyroidism (CH) occurs in approximately 1:2,000 to 1:4,000 newborns. The clinical manifestations are often subtle or not present at birth. This likely is due to trans-placental passage of some maternal thyroid hormone, while many infants have some thyroid production of their own. Common symptoms include decreased activity and increased sleep, feeding difficulty, constipation, and prolonged jaundice. On examination, common signs include myxedematous facies, large fontanels, macroglossia, a distended abdomen with umbilical hernia, and hypotonia. CH is classified into permanent and transient forms, which in turn can be divided into primary, secondary, or peripheral etiologies. Thyroid dysgenesis accounts for 85% of permanent, primary CH, while inborn errors of thyroid hormone biosynthesis (dyshormonogeneses) account for 10-15% of cases. Secondary or central CH may occur with isolated TSH deficiency, but more commonly it is associated with congenital hypopitiutarism. Transient CH most commonly occurs in preterm infants born in areas of endemic iodine deficiency. In countries with newborn screening programs in place, infants with CH are diagnosed after detection by screening tests. The diagnosis should be confirmed by finding an elevated serum TSH and low T4 or free T4 level. Other diagnostic tests, such as thyroid radionuclide uptake and scan, thyroid sonography, or serum thyroglobulin determination may help pinpoint the underlying etiology, although treatment may be started without these tests. Levothyroxine is the treatment of choice; the recommended starting dose is 10 to 15 mcg/kg/day. The immediate goals of treatment are to rapidly raise the serum T4 above 130 nmol/L (10 ug/dL) and normalize serum TSH levels. Frequent laboratory monitoring in infancy is essential to ensure optimal neurocognitive outcome. Serum TSH and free T4 should be measured every 1-2 months in the first 6 months of life and every 3-4 months thereafter. In general, the prognosis of infants detected by screening and started on treatment early is excellent, with IQs similar to sibling or classmate controls. Studies show that a lower neurocognitive outcome may occur in those infants started at a later age (> 30 days of age), on lower l-thyroxine doses than currently recommended, and in those infants with more severe hypothyroidism.

Show MeSH
Related in: MedlinePlus