hypothyroidism in paediatrics

1. HYPOTHYROIDISM
NUR AINA BINTI AB KADIR

2. CONTENTS
 Physiology
 Assessment of Thyroid Function
 Hypothyroidism
 Congenital Hypothyroidism
 Acquired Hypothyroidism
 Goiter
 Iodine Deficiency Disorders

3. PHYSIOLOGY

4. PHYSIOLOGY
 FUNCTION
 Regulation of somatic
and intellectual growth
 Intermediary
metabolism
 Thermoregulation

5. Assessment of thyroid gland
 Estimation of serum TSH and free and/or total T3 & T4.
 TSH: primary hypothyroidism
 T4 is a better indicator than T3
 Estimation of free(F) thyroid hormone
 Low FT4 and TSH : central hypothyroidism
 High TSH : primary hypothyroidism
 Persistent elevation of TSH + normal FT4 : subclinical
hypothyroidism
 High FT4 + undetectable TSH : hyperthyroid state

6. HYPOTHYROIDISM-ETIOLOGY
PRIMARY
(thyroid>95%)
SECONDARY/TERTIARY
(hypthalamus /
pituitary,<5%)
PERIPHERAL (extremely
rare)

7. ETIOLOGY-PRIMARY
Autoimmune thyroiditis
• Trapping, organificationEnzyme defect
• Endemic goiterIodine deficiency
• Aplasia, dysplasia, ectopicDysgenesis
• Surgery, radiation, infectionThyroid injury
• Thiocyanates, thionamidesGoitrogens
• Maternal TSH receptor blocking ABTrasnsient causes

8. ETIOLOGY
 PERIPHERAL
 Resistance to thyroxineMALFORMATIONS
• Septo-optic defect
dysplasia,
holoprosencephaly
CNS insults
• Trauma,surgery, radiation,
infection
CNS tumors
• Craniopharyngioma,
germinoma
SECONDARY/TERTIARY

9. CONGENITAL HYPOTHROIDISM
 Most common preventable cause of mental retardation
 Commonest cause: iodine deficiency(certain parts in
India)
 Thyroid dysgenesis : non endemic area, more in Down
syndrome
 Encompasses a spectrum ranging from complete
agenesis,partial agenesis to ectopic thyroid.
 Biosynthetic defects include disorders affecting iodine
transport, peroxidation, thyroglobulin synthesis and
deiodination.

10. CONGENITAL HYPOTHROIDISM
 Pendred syndrome associated with decreased
intracellular transport of iodine and deafness
 Transient congenital hypothyroidism may occur
following transplacental passage of TSH receptor
blocking antibodies, iodine exposure and
treatment with drugs like amiodarone.

11. CLINICAL FEATURES
 Hoarse cry
 Facial puffiness
 Umbilical hernia
 Hypotonia
 Mottling of the skin
 Lethargy
 Prolonged jaundice, constipation, unexplained
hypothermia
 Open posterior fontanelle
 Pallor

13. APPROACH
 H/O maternal thyroid disease/ingestion of antithyroid
medications
 Family H/O hypothyroidism : dyshormogenesis
 Recurrent transient hypothyroidism :maternal TSH
receptor antibody
 Residence in iodine deficient area
 Goiter : transplacental passage of antithyroid drugs/
disorders of thyroid hormone biosynthesis
 Hypoglycemia, mircropenis & midline facial defects
:hypothalamic cause

14. EVALUATION

16. MANAGEMENT
 Should be started immediately after diagnosis
 Central hypothyroidism: cortisol replacement should precede thyroid
replacemet
 Thyroxine(T4) : 10-15µg/kg/day
 Normalize: T4(1 week) & TSH (1 month)- should measured every visit
 Lifelong treatment
 Stopped for 1 month at the age 3y/o : transient congenital
hypothyroidism
 Discontinued: absence of persistent abnormality & normal thyroid
hormones

17. OUTCOME
 Early diagnosis & treatment normal intellectual
 Congenital hypothyroidism who have been
diagnosed beyond the neonatal period mental
retardation and short stature
 SCREENING
 Dried blood sample collected at postnatal age 2-4
days
 Screen first for TSH

18. ACQUIRED HYPOTHYROIDISM

19. ETIOLOGY
 Autoimmune thyroiditis
 Thyroid peroxidase antibodies present
 Other autoimmune endocrinopathies: adrenal
insufficiency, type 1 DM, hypoparathyroidism
 Congenital abnormalities: thyroid dysgenesis/inborn
error of thyroid hormone synthesis (older children
and adolescent)
 Other: iodine deficiency,goitrogens
 Combined hypothalamic-pituitary defects could be
a manifestation of neurological injury insults/tumors

20. CLINICAL FEATURES
 Short stature
 Cold intolerance
 Lethargy
 Constipation
 Delay in dentition
 Poor school performances
 Delayed puberty-but uncontrolled long-standing
hypothyroidismprecocious puberty
 Goiter: iodine deficiency, chronic lymphocytic thyroiditis,
dyshormogenesis

21. EVALUATION
 Severe short stature & mental retardation: congenital
hypothyroidism
 Round uniform smooth goiter : iodine deficiency/
disorder of thyroid hormone synthesis
 Firm nodular goiter &Family H/O acquired
hypothyroidism : autoimmune thyroiditis
 Children with central hypothyroidism: pituitary function
tests, MRI of the hypothalamic-pituitary region
 Antibodies to thyroid peroxidase enzyme(anti-TPO)-
acquired primary hypothyroidism

22. MANAGEMENT
 Treatment should be gradual
 100µg/m2/day
 Long standing cases, initial treatment should be
started at 25-50% of these dose with gradual
build up every 3-4weeks
 Given empty stomach in the morning
 Follow up: every 3months during the 1st 2 yr of
therapy and 6 monthly thereafter
 Lifelong

23. AGE THYROXINE DOSE,µg/kg/day
Neonatal period 10-15
1-6 mo 6-10
1-5yr 4-6
5-12yr 3-5
12-18yr 2-3
>18yr 1-2

24. GOITER
 Def: enlargement of the thyroid gland
 Thyromegaly: lateral lobe of the thyroid is larger than
the terminal phalanx of the thumb of the child
 ETILOGY:
 INFLAMMATORY : acute suppurative thyroiditis,
subacute thyroiditis
 INFILTRATION: autoimmune thyroiditis, neoplasm,
hemochromatosis
 INCREASED TSH LEVEL: dyshormogenesis, iodine
deficiency, unilateral agenesis
 TSH STIMULATING ANTIBODY: Graves’ disease
 COLLOID GOITER

25. EVALUATION
 Classified as diffuse/nodular goiter

26.  INVESTIGATIONS
 Thyroid function test
 Anti-TPO antibodies
 Ultrasound
 Fine needle aspiration
 MANAGEMENT
 Directed to the causes
 Autoimmune thyroiditis:
followed with annual
TFT
 ‘physiological goiter’:
thyroxine 100-200µg
daily
 Surgery: avoided

27. IODINE DEFICIENCY DISORDERS
 Refers to the wide spectrum of effects of iodine
deficiency on growth and development
 Endemic goiter
 Endemic cretinism
 Impaired mental function in children
 Goiter in adults
 Increased rate of stillbirth and perinatal and infant
mortality

28. ENDEMIC GOITER
 Prevalence of goiter in a defined population >5%

29. ENDEMIC GOITER
 Does not differ from non toxic diffuse sporadic
goiter
 Diagnosis by epidemiologic criteria
 High TSH with low T4 and T3
 Screening : 24-hr urinary iodine excretion values/
urinary iodine concentration expressed in relation to
creatinine concentration

31. ENDEMIC CRETINISM
 Disorders associated with endemic goiter and
severe iodine deficiency
 Features:
 Deaf-mutism
 Squint
 Mental retardation
 Spastic/rigid neuromotor disorder
 2types : neurological & myxedematous

32. ENDEMIC CRETINISM
 NEUROLOGICAL
 Deaf-mutism
 Squint
 Proximal spasticity
 Rigidity more in the lower
extremities
 Disorders of stance & gait
with preservation of
vegetative function
 Occasional signs of
cerebellar/ oculomotor
disturbance
 Severe mental deficiency
 MYXEDEMATOUS
 Retarded psychomotor
development
 Severe short stature
 Coarse facial features
 Myedema without deaf-
mutism

33. PREVENTION AND CONTROL
 Iodinated salt/iodized oil
 Surgical removal: relieve airway obstruction/
cosmetic purposes
 Recommended daily intake of iodine
 Children upto age 10: 40-120 µg
 Older children & adults: 150µg
 Pregnancy: additional 25 µg
 Lactation: additional 50 µg

34. Ghai Essential Pediatrics, 8th edition, pg 516-520
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REFERENCES