Congenital Hypothyroidism ??????????? Xue Fan Gu, MD, PhD Xinhua Hospital Shanghai Jiao Tong University School of Medicine - PowerPoint PPT Presentation

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Congenital Hypothyroidism ??????????? Xue Fan Gu, MD, PhD Xinhua Hospital Shanghai Jiao Tong University School of Medicine

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Title: Congenital Hypothyroidism ??????????? Xue Fan Gu, MD, PhD Xinhua Hospital Shanghai Jiao Tong University School of Medicine


1
Congenital Hypothyroidism??????????? Xue Fan
Gu, MD, PhDXinhua HospitalShanghai Jiao Tong
University School of Medicine

2
Incidence
  • Thyroid hormone deficiency may or acquired
  • Congenitalmost cases are hypoplasia or aplasia
    of the thyroid gland
  • World 13 0005 000
  • China 13 200

3

Thyroid Ontogenesis
  • 8th gestational weeks synthesis of thyroglobulin
  • 1012th gestational weeks pitutary gland begins
    to secrete TSH,thyroid gland synthesis of T3?T4
  • 30th gestational weeks hypothalamic-pitutary-thyr
    oid axis is functioning and independent of the
    maternal axis

4
  • After delivery, TSH rapidly rise reaching 6080
    uU/ml levels, and then slowly decline over the
    next few days(57d) to lt5 uU/ml levels

5
Thyroid hormone synthesis and metabolism
  • The thyroid follicle is stimulated by TSH by
    increase with TSH receptor
  • Iodine from the circulation is concentrated and
    rapidly oxidized by peroxidase to iodine
  • Iodine incorporated into tyrosyl residures on
    thyroglobuline
  • Iodothyrosines are couple an ether linkage to
    form T4 and T3

6
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7
  • T3 and T4
  • Metabolic potency of T3 is 34 times that of T4.
    Only 20 of circulating T3 is secreted by the
    thyroid
  • T3, T4 in circulation
  • Binding form70with TBG ,other with Alb.
  • Free formT4 0.03, T3 0.3

8
  • TRH

  • TSH
  • -

Hypothalamus
Anterior pituitary gland
Thyroid gland
rT3
T4
T3
Hypothylamic-pitutary-thyroid feedback regulation
9
Physiological of thyroid hormones
  • Increase oxygen consumption
  • Stimulate protein synthesis
  • Influence growth and differentiation
  • Affect carbohydrate, lipid and vitamine metabolism

10
Etiology
  • The cause may be sporadic or familial, goitrous
    or nongoitrous
  • Defective embryogenesis 75
  • Agenesis, dysgenesis, ectopia
  • Dyshormonogenesis
  • Pit-1, TSH, TSHR, TTF-I, TTF-II, Pax 8,
    TG, TPO defect, etc.
  • Iodide transport defect, organification
    defect, coupling defect, iodothyrosine deiodinase
    defect, inability of tissueses to convert T4 to
    T3
  • Deficiency or excess of iodine

11
Transient Hypothyroidism
  • Premature
  • Maternal medications (propylthiouracil,methimazol)
  • Maternal antibody
  • Iodine deficiency hypothyroidism in iodine
    deficiency area

12
Other Causes
  • Pitutary/hypothalamis hypothyroidism
  • Rare,lt5, measurement of TSH levels fail to
    revel patient with pitutary-hypothalamic
    hypothyroidism, since they have low TSH

13
Classification According To TSH Level
  • TSH level rise
  • Primary hypothyroidism
  • Transient hypothyroidism
  • TSH level in normal
  • Pitutary/hypothalamis hypothyroidism
  • low TBG

14
Clinical Findings In Newborns and Infants
  • Absent symptom during the first few weeks of life
  • A few have birth weightgt3.5kg prolongation of
    physiological icterus,constipation, hoarse cry,
    feeding or sucking difficulties

15
  • Progress Manifestation
  • Pulse is slow, heart murnures, cardiomegaly,hypoth
    ermia, hypotonia, enlarged tongue, skin cold and
    dry, umbilical hernia, hair is dry
  • Mental retardation
  • growth stunted

16
?????? 8y
17
Hypothyroidism caused by Pituitary-hypothalami
s
  • Without symptom in neonatal period
  • May be with other pituitaty hormone deficiency
  • GH deficiency short stature
  • ACTH deficiency hypoglycemia
  • ADH deficiency diabetes incipidus

18
Laboratory findings
  • TSH in neonatal screening programs lt1015 mu/L
  • Normal range for neonate
  • T4 84-210 nmol/l(6.5-16.3ug/dl)
  • FT4 12-28 pmol/l(0.9-2.2ng/dl)
  • TSH 1.7-9.1 mu/L(1.7-9.1 uU/ml)

19
Scintigraphy
  • 99mTc?123I scintigraphy
  • B ultrasound examination
  • X ray retardation of skeletal maturation (bone
    age)

20
Treatment
  • Principal
  • Give thyroxine as early as possible
  • TSH and FT4 should be monitored and maintained in
    the normal range
  • Confirmation of diagnosis may be necessary for
    some infant to rule out the possibility of
    transient hypothyroidism at 23 years old

21
  • Dose of thyroxine(L-T4)
  • ----------------------
  • Age µg/day ug/kg/day
  • ----------------------
  • 06m 2550
    8.510
  • 612m 50100
    58
  • 15y 75100
    56
  • 612y 100150
    45
  • 12y to adult 100200
    23
  • ----------------------

22
CH (4y) before treatment after one
year treatment
23
Flow Chart of Neonatal Screening for CH
  • TSH of retesteted sample gt Cut off
    point
  • Recall of
    neonate
  • retested TSH levelgt Cut off point
  • Serum FT3,FT4,TSH X-ray of knee
  • FT4 TSH delayed BA FT4 normal,TSH
    normal BA
  • CH
    Hyperthyrotropinemia

24
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