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Senoir paeds > HYPOTHYROIDISM/THYROIDIT IS > Flashcards

HYPOTHYROIDISM/THYROIDIT IS Flashcards

1
Q

Hypothyroidism is one of the most common endocrine disorders of childhood.

Hypothyroidism may be congenital or can be acquired.

Failure to institute early treatment in congenital cases causes _________ .

Untreated hypothyroidism in older children leads to __________ as well as ____________ and ______________.

A

mental retardation

growth failure

slowed metabolism and impaired memory

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2
Q

EMBRYOLOGY

The thyroid gland is the first of the body’s endocrine glands to develop.
Develops from
 a __________ derived from the primitive ___________[ and
 _______________ from the ___________________________.

A

median anlage; pharyngeal floor

paired lateral anlagen

4th pharyngobronchial pouch

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3
Q

MOLECULAR BASIS
Growth and differentiation of thyroid gland is linked to
2 transcription factors:
 _______ and
 _______
Paired box family of DNA binding protein, _______

A

TTF-1

TTF-2

PAX-8

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4
Q

Organogenesis

The developing thyroid is first visible in the floor of the primitive _________ by embryonic day E20-22.

_________ _________ cells form the thyroid anlage, distinguishing themselves from their neighbors in a process defined as _________. A defect in this process should result in _________.

During the second stage of early thyroid morphogenesis the thyroid anlage invades the surrounding mesenchyme, forming a bud which proliferates and migrates from the pharyngeal floor through the anterior midline of the neck.

The thyroid primordium becomes a bilobed structure by day _________ and reaches its final position around day _________. An error during lobulation results in _________, and an impaired descent results in _________

A

pharynx ; Endodermal epithelium

specification.; thyroid agenesis.

E24-32 ; E48-50.

hemiagenesis ; ectopic thyroid tissue.

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5
Q

Thyroid hormone synthesis.

 _________________________ stimulates iodi(ne or de?) transport into the thyroid
gland by the __________________.

_________ , a __________________ is thought to transport iodide into the colloid from the thyrocyte.
Iodide is ________ by hydrogen peroxide, generated by NADPH oxidase system (ThOX)

A

TSH receptor (TSHR) bound to TSH

Iodide; sodium iodide symporter (NIS)

Pendrin; chloride-iodide transporter

oxidised

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6
Q

Thyroid hormone synthesis (2)

Iodine is Bound to _______ residues in ____________ to form ____________ (iodide organification).

 Some of these hormonally inactive iodotyrosine residues [ __________ and ____________ ] couple to form the hormonally active iodothyronines, ______ and _______

A

tyrosine; thyroglobulin (TG); iodotyrosine

monoiodotyrosine (MIT) and diiodotyrosine DIT

T4 and T3.

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7
Q

___________________ catalyses the oxidation, organification, and coupling reactions.

A

Thyroid peroxidase (TPO)

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8
Q

Functions of Thyroid Hormones
CNS – Brain __________
Growth and development
__________ hormone metabolism
Increases __________ and __________ production
__________ closure

A

Brain maturation

Growth hormone ; basal metabolic rate

heat production ; Cerebral fontanelle

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9
Q

Functions of Thyroid hormone

GIT - _____________ activities
Regulates _________ of carbohydrates, proteins and fats

INTEGUMENTARY – ______ maturation SKELETAL – _________ maturation

A

Hepatic enzymes

metabolism

Skin ; Epiphyseal

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10
Q

Aetiology of CH

Primary

  1. Thyroid dysgenesis (_____,_______,_______) a) __________
    b) __________ and
    c) ectopic usually __________
  2. Synthetic defects
    a) genetic defect of thyroid hormone biosynthesis (TPO, NIS, pendrin, TG, oxidase, G protein, diiodinase, other enzymes)
    b) thyroid hypoplasia as a result of ________ loss of function mutation (~5%)
  3. __________ ____________ disease and/or treatment
  4. Maternal use of ___________
A

TTF-1, TTF-2, PAX-8

agenesis; dysplasia ; sublingual gland

TSHR ; Maternal Autoimmune thyroid

amiodarone

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11
Q

Aetiology of CH (2)

B. Secondary (________) hypothyroidism
C. Tertiary (_____________) hypothyroidism

•___________ to thyroid hormones (peripheral and pituitary receptors)

A

pituitary

hypothalamic

Resistance

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12
Q

Newborn Screening

Now routine in most developed countries
Treatment initiated within _______ with ______________ and normal mental outcome.

_________________ samples via skin puncture:3 most common methods-
primary _____ screen
 primary _____ screen with _________
Primary ______ and ______ screen

A

45days

Thyroxine replacement

Dried blood spot; TSH

T4; confirmatory TSH

TSH ; T4

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13
Q

Evaluation and Management

High index of suspicion
Maternal history of ___________ disease
Maternal treatment with ________ drugs or _________
Maternal ____________
Exposure of mother and/neonate to ___________ amounts of iodide may cause transient neonatal goitre & hypothyroidism.

A

autoimmune thyroid

antithyroid; amiodarone

iodine deficiency

supraphysiologic

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14
Q

Congenital Hypothyroidism Score

Score >__= hypothyroidism but requires more evaluation

A

5

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15
Q

Other Investigations in hypothyroidism

Thyroid imaging- _____ or __________ scan

Serum Thyroglobulin (Tg)- __________ confirms absence of thyroid tissue or Tg synthetic defects.

Neonates with _____ total & free T4 and ________ or ___________ TSH must be evaluated for hypothalamo-pituitary hypothyroidism. (combined or isolated defects).

A

USS or Technetium

undetectable

low; normal or mildly elevated

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16
Q

Treatment of hypothyroidism

L-T4: —— μg/kg by _____ _______ daily.

_____________ tablets are easily crushed and can be given in a spoon with a small amount of water, formula, or cereal.
Suspensions are not commercially available and are not recommended because maintaining a consistent concentration of levothyroxine in solution is difficult.

A

10; mouth; once

Levothyroxine

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17
Q

Goal of therapy in hypothyroidism

__________ TSH and maintain T4 and FT4 in ________ half of reference range.

Assess permanence of CH:
Thyroid scan shows ectopic/absent gland - CH is permanent

TSH is <50 mU/L and there is no increase in TSH after newborn period, then _______________________

If TSH increases off therapy, consider _______________

A

Normalize; upper

tail off therapy at 3 yr of age

permanent CH

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18
Q

Treatment of hypothyroidism

Caution: therapy in cases of combined pituitary hormone deficiency: ___________ is required before L-thyroxine therapy.

Neonates with low cortisol must be treated with ____________ before T4 therapy.
This reduces the risk of ___________ resulting from _________________________________ from thyroid hormone replacement.

A

Serum cortisol

hydrocortisone

adrenal crisis

increased demands from enhanced metabolism

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19
Q

Monitoring of Therapy
Recheck T4, TSH
2–4 wk after initial treatment is begun Every 1–2 months in the first 6 months Every 3–4 months between 6 months
and 3 yrs of age
Every 6–12 months from 3 yrs of age to
end of growth
 ___________ monitoring is essential!

A

Growth

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20
Q

TRANSIENT CONGENITAL HYPOTHYROIDISM

Caused by:

•_________ deficiency
•__________________ (to 3 month of life)
•Foetal or neonatal ___________________
•Maternal __________ therapy
•_________ infants

A

Iodine

TSHR-blocking antibodies

exposure to high amounts of iodine

amiodarone; premature

21
Q

ACQUIRED HYPOTHYROIDISM (AH)

Aetiology
Primary hypothyroidism
• _______________________ thyroiditis:
 __________ (_________)
 __________ (primary _________)
•__________ thyroiditis

Iodine deficiency (endemic goiter)

A

Chronic lymphocytic

Goitrous ; Hashimoto’s

Atrophic; myxedema

Subacute

22
Q

ACQUIRED HYPOTHYROIDISM (AH)

Aetiology

Primary hypothyroidism
 Drugs or goitrogens
Antithyroid drugs (PTU, MMI, carbimazole) Anticonvulsants
Other (lithium, thionamides, aminosalicylic acid, aminoglutethimide)
Goitrogens (cassava, water pollutants, cabbage, sweet potatoes, cauliflower, broccoli, soybeans)
Iodine deficiency goitre

A

Okay🌚

23
Q

Acquired hypothyroidism- Aetiology
Secondary or tertiary hypothyroidism

Hypothalamic or pituitary ________ (especially ______________ )
Treatment of brain and other tumors
_________
__________

A

tumor

craniopharyngioma

Surgery

Radiation

24
Q

Acquired hypothyroidism-Clinical Features
Typically ___________ in onset.

•___________
•Local symptoms : ___________, ___________, or of a ___________ sensation in their neck and/or throat.
•________ growth
•___________ maturation

A

insidious ; Goiter

dysphagia ; hoarseness, ;?pressure

Slow; Delayed osseous

25
Q

Acquired hypothyroidism-Clinical Features

•Mild weight _______ despite _______eased appetite is characteristic of the child who has a hypothyroid condition.
•Moderate-to-severe _______ in children is not typical for hypothyroidism.
•A decreased _______ is a more constant finding than weight _______.

A

gain ; decreased

obesity

growth rate ; weight gain.

26
Q

Acquired hypothyroidism-Clinical Features

Lethargy
_________________ body proportions
___________ hair
_______ dentition
Cool, dry, skin
_______ nails
Delayed relaxation phase of deep tendon reflexes
Decreased energy
________
Sleep disturbance, typically _______________
_______ intolerance
Constipation

A

Immature upper-to-lower

Dey Coarse

Delayed; Brittle; Puffiness

obstructive sleep apnea

Cold

27
Q

Acquired hypothyroidism-Clinical Features

Galactorrhea:
develops in primary hypothyroidism secondary to TRH secretion from the hypothalamus.

TRH stimulates the _____________ to release ________ and ————- .

Resolves as prolactin concentrations fall with thyroid replacement.

A

anterior pituitary

TSH and prolactin

28
Q

THYROIDITIS
Inflammation of the thyroid gland.

Major classes:

 (1) ______________ thyroiditis
 (2) ____________ thyroiditis (___________ Syndrome)
 (3) _______________ thyroiditis (___________).

A

 (1) Acute suppurative thyroiditis
 (2) Subacute thyroiditis (De Quervain Syndrome)
 (3) Chronic lymphocytic thyroiditis (Hashimoto’s).

29
Q

Acute Suppurative Thyroiditis

Is due to _____________ .
(Common or Rare?) in childhood because the thyroid is remarkably ________________.

May be associated with other head and neck infections.

A

bacterial infection.

rare ; resistant to haematogenously spread infection.

30
Q

Acute Suppurative Thyroiditis
Most cases involve the _______ lobe of the thyroid and are associated with a developmental abnormality of thyroid __________ and the persistence of a pyriform sinus from the pharynx to the thyroid capsule.

Usual organisms responsible include __________,____________, and ___________. Other aerobic or anaerobic bacteria may also be involved.

A

left; migration

Staph aureus, Strep hemolyticus, and Pneumococcus

31
Q

Acute Suppurative Thyroiditis
Present with:
 ______ onset of pain
 _______
 _________
 Unilateral or bilateral thyroid _________
 Local _________
 Regional __________
 _________ may develop
 Signs of hyperthyroidism are rare

A

Acute Suppurative Thyroiditis
Present with:
 Acute onset of pain
 Dysphagia
 Fever
 Unilateral or bilateral thyroid enlargement  Local tenderness
 Regional lymphadenopathy
 Abscess may develop
 Signs of hyperthyroidism are rare

32
Q

Acute Suppurative Thyroiditis
 Investigations
_________
TFTs usually _______
Thyroid Scan
Thin needle aspiration and culture may be helpful in antimicrobial selection.
 Treatment with antibiotics and antipyretics.
Course usually limited to 2-4weeks.

A

Leucocytosis; normal

33
Q

Subacute thyroiditis

Due to viral processes it usually follows a _________ _________.
Viral illnesses like _________ , _________, influenza, infectious mononucleosis, adenoviral or Coxsackie , myocarditis, or the common cold.

Other illnesses or situations associated with subacute thyroiditis include catscratch fever, sarcoidosis, Q fever, malaria.

The disease is more common in individuals with ______________________

A

prodromal viral illness

Measles, mumps

human leukocyte antigen (HLA)–Bw35.

34
Q

Subacute Thyroiditis
Neck ____________ and ____________ may occur, and it may be mildly or severely tender.
Occasionally, the initial symptoms are those of ____________.
Fever is usually _________ grade.
Systemic symptoms such as weakness, fatigue, malaise may be present.

A

tenderness ; swelling

hyperthyroidism.

low

35
Q

Subacute Thyroiditis
Serum T3 and T4 levels usually __________ .
Thyroidal Radioiodine Uptake is _______ or _______ [thyroidal cell damage].

S & S of hyperthyroidism persist for 1-4weeks

Subsequent period of transient hypothyroidism [as the thyroid gland recovers]
Total course runs 2 to 9 months.

A

increased.

low or absent

36
Q

Subacute Thyroiditis
Self-limiting, therefore, the goals of treatment are to ____________ and to control the _______ thyroid function.
Treatment:
Large doses of _________________ agents
In severe cases, ____________ Rx may be helpful.

A

relieve discomfort

abnormal

anti-inflammatory ; corticosteroid

37
Q

Subacute thyroiditis

___________ can be used to reduce signs and symptoms of hyperthyroidism.
Low-dose ___________ may be necessary in some patients who develop hypothyroidism.
Most patients recover without a residual defect in thyroid function.

A

Propranolol

levothyroxine

38
Q

Chronic Lymphocytic Thyroiditis (CLT, Hashimoto’s)

Is the most common cause of acquired hypothyroidism and goiter in children living in iodine-sufficient areas.
CLT appears to require both _________________ trigger and a ____________ defect in immune surveillance.
HLA-DR3, 4 and 5 have been associated.

A

an environmental

genetically determined

39
Q

Chronic Lymphocytic Thyroiditis (CLT)

Family history in 30-40% of patients.
2:1 _____________ preponderance
Typically presents during _____________ ; however, it may present any time in life.

A

female-to-male

adolescence

40
Q

Chronic Lymphocytic Thyroiditis

Asymptomatic thyroiditis with or without thyroid function abnormalities may be discovered upon routine screening of children at high risk:
_________,
 Kline-Felter’s
 _________ syndrome
 Other autoimmune endocrine disorders (eg, Type 1 diabetes, Addison disease, Vitiligo).

A

Down syndrome; Turner

41
Q

Chronic Lymphocytic Thyroiditis (CLT)
Observed in the following 3 patterns:
 (1) Goiter that is usually _________ and ____________ . The thyroid gland is frequently ______ times its normal size and may be larger.
Although it may not be enlarged symmetrically.
The gland may initially be ______ but then takes on a ______ feeling with _________ consistency and a seedlike surface secondary to hyperplasia of the normal lobular architecture.

A

diffuse and non-tender

2-3

soft; firm; rubbery

42
Q

Chronic Lymphocytic Thyroiditis
Observed in the following 3 patterns:

 (2) approximately 5-10% of children with CLT initially present with symptoms of ____________: poor attention span, hyperactivity, restlessness, heat intolerance, weight loss, and tremors or loose stools.

This _____-lived _________ phase may be secondary to autonomous release of stored T4 and T3 (with progressive inflammatory lymphocytic infiltration of the thyroid)
or secondary to an initial predominance of TSH-receptor stimulating immunoglobulins (termed “ ___________”).

A

hyperthyroidism; short

thyrotoxic; Hashitoxicosis

43
Q

Hashitoxicosis-2/2
This clinical picture may suggest a diagnosis of ______________ .

A

Graves disease

44
Q

The thyrotoxic phase of CLT can be differentiated from Graves disease in that, in CLT
 it is ___________,
is not associated with __________,
 and is usually associated with a decreased and nonuniform uptake of radioactive iodine.
This “Hashitoxicosis” phase is usually followed by the more characteristic ___________ phase.

A

transient; exophthalmos

hypothyroid

45
Q

Chronic Lymphocytic Thyroiditis
Observed in the following 3 patterns:

(3) Symptoms of hypothyroidism:
In children, this frequently includes _____ growth or _______ stature.
Adolescent girls may have primary or secondary _________.
Boys may have _______ _______.
Because the disease develops slowly, the patient or parent may not notice other signs of hypothyroidism, including constipation, lethargy, and cold intolerance.
Child with diabetes may have _____easing insulin requirement

A

poor; short

amenorrhea ; Delayed puberty

Decreasing

46
Q

Chronic Lymphocytic Thyroiditis
Initially, an enlarged, lumpy, bumpy, and (tender or nontender?) thyroid is often present.
The gland may not be enlarged, particularly in children who have _______________.
The histologic appearance of CLT includes lymphocytic infiltration, formation of lymphoid follicles, and follicular cell hyperplasia.

A

nontender

profound hypothyroidism

47
Q

Acquired Hypothyroidism- Follow up

_________ is the optimal parameter to guide dosing of thyroid hormone replacement,

except in patients with secondary or tertiary hypothyroidism where measuring _________ is a more reliable indicator.

In the rare syndromes of thyroid hormone resistance, serum TSH levels are __________ in the presence of _____________ serum total T4 concentration.

A

Serum TSH

serum free T4

elevated

48
Q

Children with AH who receive adequate treatment at least ______ before the onset of puberty typically achieve a final adult height consistent with their genetic potential.
Over-treating with thyroid hormone does not ______________________ and may compromise ____________ by advancing skeletal maturation.

A

5 years

enhance catch-up growth

final adult height

Senoir paeds (15 decks)

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