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PCF Exam 3 > Thyroid Disorders > Flashcards

Thyroid Disorders Flashcards

1
Q

In the Hypothalamic-Pituitary Thyroid axis, the ____ secretes thyroid-releasing hormone (TRH)

A

Hypothalamus

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2
Q

The thyroid gland utilizes ______ & _____ to produce T3 & T4

A

Iodine & Thyroglobulin

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3
Q

Upon entering _____ , T3/T4 are cleaved via enzymes into a lipophilic structure

A

target tissues

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4
Q

Once T3 & T4 enter the blood stream they will ______ pituitary TSH secretion

A

INHIBIT

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5
Q

T3 & T4 are produced in what cells

A

Follicular Cell (responsible for
synthesizing & releasing)

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6
Q

Calcitonin is produced in what cells

A

Para-follicular cells

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7
Q

Solubility of T3 and T4 hormones

A

Lipid-Soluble
99% these hormones circulate within
the blood BOUND to thyroxine
binding globulin (TBG) and/or
albumin
* The unbound hormone, 1%, is
PHYSIOLOGICALLY ACTIVE
* T3 is more physiologically active
* T4 is changed in to T3

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8
Q

Solubility of Calcitonin

A

Peptide hormone (water soluble – travel
in the blood & binds on receptor
proteins)

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9
Q

FOUR main METABOLIC FUNCTIONS of T3/T4

A
  1. ↑ in Basal Metabolic Rate = ↑ ATP production by all cells in the
    body, ↑ heat generation & O2 consumption.
  2. ↑ CARDIAC OUTPUT = ↑ heart rate & contractility, ↑ blood pressure
  3. Stimulates BONE maturation & growth = ↑ RBC’s
  4. Increases metabolism (↑ gluconeogenesis, ↑ glycolysis, ↑ glucose
    absorption, ↑ lipolysis, ↑ protein turnover)
    * BRAIN = clear thinking, improved mood, & energy
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10
Q

Thyroid follicles are formed by thyroid epithelial cells surrounding _____ , which contains thyroglobulin.

A

proteinaceous colloid

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11
Q

Follicular cells, which are polarized, synthesize thyroglobulin & carry out
______

A

thyroid hormone biosynthesis

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12
Q

Subclinical hyper/hypo-thyroidism is

A

– Normal FT4 with ↑ or ↓TSH
– No physical symptoms

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13
Q

What is Euthyroid

A

Euthyroid
– Normal TSH
– Euthyroid sick syndrome
* ↓ T4 + symptoms

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14
Q

Secondary thyroidism refers to the _____

A

Pituitary

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15
Q

Hypothyroidism (Central Hypothyroidism) is

A

Insufficient stimulation of the thyroid gland by TSH (hypothalamic or pituitary disease)

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16
Q

Secondary hyperthyroidism involves what

A

TSH producing tumor

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17
Q

Hyperthyroidism Epidemiology

A

Prevalence
– 1.3%, more common in women than men at 5:1 ratio
– 4-5% in older women
– More common in smokers.

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18
Q

Primary vs. Secondary Hyperthyroidism Etiology

A

Primary
– Graves Disease (autoimmune)
– Subacute thyroiditis
* “DeQuervain” thyroiditis
– Cause = viral infection
– ↑ iodine intake
– ↑intake of exogenous thyroid
hormone
– Drugs (Amiodarone)

Secondary
– ↑ TSH
* Anterior pituitary
adenoma
– ↑ TRH secretion
* Hypothalamic tumor

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19
Q

An Autoimmune disorder of the thyroid gland, characterized by ↑ synthesis & release of thyroid hormones

A

Grave’s disease

20
Q

Features of Graves Disease

A

Autoimmune disorder of the thyroid gland, characterized by ↑
synthesis & release of thyroid hormones.
* More common in women than men 8:1
* Onset 20-40 years
* Associated with ↑ antibodies, exophthalmos, pretibial myxedema,
onycholysis (separation of nail from its bed)
* ↑ risk other autoimmune disorders

21
Q

Subjective (symptoms) and Objective findings (signs) in Hyperthyroidism

A

Subjective complaints (SYMPTOMS):
– Sweating, weight loss or gain, anxiety, palpitations, loose stools,
heat intolerance, irritability, fatigue, weakness, menstrual
irregularity.

  • Objective Findings (Signs):
    – Tachycardia; warm, moist skin; stare; tremor; exophthalmos -
    (abnormal protrusion of the eyeball or eyeballs d/t retro-orbital
    eye fat/infiltration)
22
Q

exophthalmos is

A

abnormal protrusion of the eyeball or eyeballs d/t retro-orbital
eye fat/infiltration

23
Q

Epidemiology of Hypothyroidism

A

Prevalence: >1% of population, >5% over 60 yo

24
Q

Primary causes of Hypothyroidism

A

PRIMARY CAUSES
1. Failure of the thyroid gland
(95% of all cases)
* Autoimmune disease
* HASHIMOTOS THYROIDITIS
– MOST COMMON CAUSE

  1. Iodine deficiency/excess
  2. Drugs (Amiodarone, interferon)
  3. Iatrogenic
    – Resection and/or
    radioiodine therapy
25
Q

Secondary causes of Hypothyroidism

A
  1. TSH deficiency
  2. TRH deficiency
    – Mass lesions,
    congenital/genetic
    abnormalities/acquired
    (concussions),
    functions
    (aging/anorexia)
26
Q

HASHIMOTOS THYROIDITIS is the most common cause of what

A

Primary Hypothyroidism

27
Q

What is HASHIMOTOS THYROIDITIS

A

Autoimmune disease
* Patients can frequently have other side effects due to co-occurring
autoimmune diseases:
* Eg// Addison disease, hypoparathyroidism, diabetes mellitus I,
pernicious anemia, sjorgen syndrome, vitiligo
* 5% have celiac disease

28
Q

Subjective (symptoms) and Objective findings (signs) in Hypothyroidism

A
  • Subjective complaints (SYMPTOMS):
    – Weakness, fatigue, lethargy, arthralgia’s, cold intolerance,
    constipation, weight gain, depression, menorrhagia, headache,
    carpal tunnel syndrome, Raynaud’s syndrome.
  • Objective findings (SIGNS):
    – Bradycardia; thin, brittle nails, thinning of hair; peripheral
    edema, puffy face & eyelids, skin pallor or yellowing; delayed
    deep tendon reflexes, palpably enlarged thyroid (GOITER),
    hoarseness
  • Also known as: mild to severe MYXEDEMA
29
Q

Severe Adult Hypothyroidism is also known as _____

A

Myxedema Crisis
* Swelling of the skin & underlying tissues
– Waxy consistency (firm & inelastic)
– Non-pitting edema,
– Dry skin & hair (frowzy hair)
– Dull apathetic appearance, swollen lips, thickened nose.

30
Q

Myxedema Crisis is a ____ form of hypothyroidism

A

Life threatening
Impaired cognition → Confusion → Somnolence → Myxedema coma

31
Q

Most common population for to get Myexedema Crisis

A

elderly women who have had a stroke or
stopped taking thyroxine medication

32
Q

Characteristics of Hypo vs. Hyper thyroidism

A

Hypothyroidism
* Foggy thinking
* Depressed
* Low heart rate
* Low blood pressure
* Anemia → cold, pale, tired
* Low energy/fatigued
* Obesity (↓ use of fatty acids 2°↓ ATP)

Hyperthyroidism
* Agitated
* Irritable
* Rapid Heart rate/palpitations
* High blood pressure
* Polycythemia → hot, flushed, restless
* Restless
* Thinner

33
Q

Characteristics of Euthyroid Sick Syndrome

A

Pt without known thyroid disease, with ↓ serum FT4 & normal TSH
1. Pregnancy
2. Major surgery
3. Chemotherapeutic agents
4. Viral thyroiditis
* Initial (typically) hyperthyroid state then → hypothyroid

  1. Critical illness
  2. Liver/renal disease
  3. Malnutrition
34
Q

Laboratory tests for Thyroid Diagnostic testing

A
  1. Thyroid-stimulating hormone (TSH)
  2. Most sensitive test for primary hypo/hyper-thyroidism.
  3. SINGLE best screening test for HYPOthyroidism.
  4. Free Thyroxine (FT4) – commonly used along with TSH.
  5. Free Triiodothyronine (FT3) – more sensitive for hyperthyroidism
  6. Anti-thyroid antibodies
    – Anti-thyroglobulin (Tg) Ab
    – Anti-thyroid peroxidase (TPO) ab
35
Q

SINGLE best screening test for HYPOthyroidism

A

Lab test for Thyroid-stimulating hormone (TSH)

36
Q

You have low TSH and low serum T4/T3

A

Central Hypothyroidism

37
Q

High TSH and Low T4/T3

A

Primary hypothyroidism

38
Q

Low TSH and High T4/T3

A

Primary Hyperthyroidism

39
Q

High TSH and High T4/T3

A

Secondary Hyperthyroidism

40
Q

Imaging studies for Thyroid diagnostic testing

A
  • Imaging is usually not needed in most cases of thyroid disease
  • Ultrasound = Test of Choice (no radiation)
    – Thyroid nodules
  • fluid vs. solid
  • to guide biopsy
  • Radioiodine scan – Confirm cancerous nodule or Graves dz
  • Chest X-ray – Metastatic thyroid cancer to the lungs (typical)
  • CT/MRI = (MRI preferred) Metastatic thyroid cancer throughout
    the body
41
Q

Additional Thyroid testing

A
  • Fine-needle Aspiration (FNA)
    Biopsy
    – Best diagnostic method for
    thyroid cancer
  • Thyroid uptake scan (131I)
    – Cancers are usually found
    as “cold” spots
  • 99mTc scan
    – Evaluates nodule vascularity
    – Ultrasonography
    – Used to get FNA
    – Helps assess malignancy
    – Useful for nodule
    monitoring
42
Q

Management of Hypothyroidism

A
  • Levothyroxine (Synthroid®)– Synthetic T4 – MOST COMMON
  • Liothyronin (Cytomel®) – Synthetic T3
  • Thyroid (porcine) (Armour Throid®) – Natural T3 & T4 mixture, 1:4 ratio
43
Q

Instructions for levothyroxine (Synthroid®)

A
  • Take in the AM, empty stomach with water (food ↓ absorption)
  • Take 30 minutes before any food or other medications
  • Food ↓ absorption (esp. grapefruit)
44
Q

You should Retest TSH & T4 (or FT4) in _____ after medication initiation

A

6-8 weeks

45
Q

Management of Hyperthyroidism

A
  • Thiourea Meds
    – Methimazole (Tapazole®): Inhibits thyroid hormone synthesis
    – Propylthiouracil: Inhibits thyroid hormone synthesis
  • Propranolol ER (Inderal LA®) – Treat symptoms of tachycardia & anxiety
  • Thyroid ablation – Radioactive Iodine (131I), Destroys thyroid tissue
  • Thyroidectomy

PCF Exam 3 (7 decks)

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