HYPOTHYROIDISM/THYROIDIT IS Flashcards by Iseoluwa Ojo

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 ______________.

mental retardation

growth failure

slowed metabolism and impaired memory

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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 ___________________________.

median anlage; pharyngeal floor

paired lateral anlagen

4th pharyngobronchial pouch

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

TTF-1

TTF-2

PAX-8

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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 _________

pharynx ; Endodermal epithelium

specification.; thyroid agenesis.

E24-32 ; E48-50.

hemiagenesis ; ectopic thyroid tissue.

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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)

TSH receptor (TSHR) bound to TSH

Iodide; sodium iodide symporter (NIS)

Pendrin; chloride-iodide transporter

oxidised

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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 _______

tyrosine; thyroglobulin (TG); iodotyrosine

monoiodotyrosine (MIT) and diiodotyrosine DIT

T4 and T3.

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___________________ catalyses the oxidation, organification, and coupling reactions.

Thyroid peroxidase (TPO)

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

Brain maturation

Growth hormone ; basal metabolic rate

heat production ; Cerebral fontanelle

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Functions of Thyroid hormone

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

INTEGUMENTARY – ______ maturation SKELETAL – _________ maturation

Hepatic enzymes

metabolism

Skin ; Epiphyseal

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Aetiology of CH

Primary

Thyroid dysgenesis (_____,_______,_______) a) __________
b) __________ and
c) ectopic usually __________
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%)
__________ ____________ disease and/or treatment
Maternal use of ___________

TTF-1, TTF-2, PAX-8

agenesis; dysplasia ; sublingual gland

TSHR ; Maternal Autoimmune thyroid

amiodarone

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Aetiology of CH (2)

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

•___________ to thyroid hormones (peripheral and pituitary receptors)

pituitary

hypothalamic

Resistance

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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

45days

Thyroxine replacement

Dried blood spot; TSH

T4; confirmatory TSH

TSH ; T4

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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.

autoimmune thyroid

antithyroid; amiodarone

iodine deficiency

supraphysiologic

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Congenital Hypothyroidism Score

Score >__= hypothyroidism but requires more evaluation

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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).

USS or Technetium

undetectable

low; normal or mildly elevated

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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.

10; mouth; once

Levothyroxine

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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 _______________

Normalize; upper

tail off therapy at 3 yr of age

permanent CH

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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.

Serum cortisol

hydrocortisone

adrenal crisis

increased demands from enhanced metabolism

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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!

Growth

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TRANSIENT CONGENITAL HYPOTHYROIDISM

Caused by:

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

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Iodine

TSHR-blocking antibodies

exposure to high amounts of iodine

amiodarone; premature

ACQUIRED HYPOTHYROIDISM (AH)

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

Iodine deficiency (endemic goiter)

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Chronic lymphocytic

Goitrous ; Hashimoto’s

Atrophic; myxedema

Subacute

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

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Okay🌚

Acquired hypothyroidism- Aetiology
Secondary or tertiary hypothyroidism

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

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tumor

craniopharyngioma

Surgery

Radiation

Acquired hypothyroidism-Clinical Features
Typically ___________ in onset.

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

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insidious ; Goiter

dysphagia ; hoarseness, ;?pressure

Slow; Delayed osseous

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 _______.

gain ; decreased obesity growth rate ; weight gain.

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

Immature upper-to-lower Dey Coarse Delayed; Brittle; Puffiness obstructive sleep apnea Cold

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.

anterior pituitary TSH and prolactin

THYROIDITIS Inflammation of the thyroid gland. Major classes:  (1) ______________ thyroiditis  (2) ____________ thyroiditis (___________ Syndrome)  (3) _______________ thyroiditis (___________).

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

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.

bacterial infection. rare ; resistant to haematogenously spread infection.

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.

left; migration Staph aureus, Strep hemolyticus, and Pneumococcus

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

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

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.

Leucocytosis; normal

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 ______________________

prodromal viral illness Measles, mumps human leukocyte antigen (HLA)–Bw35.

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.

tenderness ; swelling hyperthyroidism. low

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.

increased. low or absent

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.

relieve discomfort abnormal anti-inflammatory ; corticosteroid

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.

Propranolol levothyroxine

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.

an environmental genetically determined

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.

female-to-male adolescence

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).

Down syndrome; Turner

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.

diffuse and non-tender 2-3 soft; firm; rubbery

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 “ ___________”).

hyperthyroidism; short thyrotoxic; Hashitoxicosis

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

Graves disease

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.

transient; exophthalmos hypothyroid

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

poor; short amenorrhea ; Delayed puberty Decreasing

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.

nontender profound hypothyroidism

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.

Serum TSH serum free T4 elevated

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.

5 years enhance catch-up growth final adult height

HYPOTHYROIDISM/THYROIDIT IS Flashcards

(48 cards)