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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
Secondary causes of Hypothyroidism
1. TSH deficiency 2. TRH deficiency – Mass lesions, congenital/genetic abnormalities/acquired (concussions), functions (aging/anorexia)
26
HASHIMOTOS THYROIDITIS is the most common cause of what
Primary Hypothyroidism
27
What is HASHIMOTOS THYROIDITIS
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
Subjective (symptoms) and Objective findings (signs) in Hypothyroidism
* 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
Severe Adult Hypothyroidism is also known as _____
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
Myxedema Crisis is a ____ form of hypothyroidism
Life threatening Impaired cognition → Confusion → Somnolence → Myxedema coma
31
Most common population for to get Myexedema Crisis
elderly women who have had a stroke or stopped taking thyroxine medication
32
Characteristics of Hypo vs. Hyper thyroidism
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
Characteristics of Euthyroid Sick Syndrome
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 5. Critical illness 6. Liver/renal disease 7. Malnutrition
34
Laboratory tests for Thyroid Diagnostic testing
1. Thyroid-stimulating hormone (TSH) 1. Most sensitive test for primary hypo/hyper-thyroidism. 2. SINGLE best screening test for HYPOthyroidism. 2. Free Thyroxine (FT4) – commonly used along with TSH. 3. Free Triiodothyronine (FT3) – more sensitive for hyperthyroidism 4. Anti-thyroid antibodies – Anti-thyroglobulin (Tg) Ab – Anti-thyroid peroxidase (TPO) ab
35
SINGLE best screening test for HYPOthyroidism
Lab test for Thyroid-stimulating hormone (TSH)
36
You have low TSH and low serum T4/T3
Central Hypothyroidism
37
High TSH and Low T4/T3
Primary hypothyroidism
38
Low TSH and High T4/T3
Primary Hyperthyroidism
39
High TSH and High T4/T3
Secondary Hyperthyroidism
40
Imaging studies for Thyroid diagnostic testing
* 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
Additional Thyroid testing
* 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
Management of Hypothyroidism
* Levothyroxine (Synthroid®)– Synthetic T4 – MOST COMMON * Liothyronin (Cytomel®) – Synthetic T3 * Thyroid (porcine) (Armour Throid®) – Natural T3 & T4 mixture, 1:4 ratio
43
Instructions for levothyroxine (Synthroid®)
* Take in the AM, empty stomach with water (food ↓ absorption) * Take 30 minutes before any food or other medications * Food ↓ absorption (esp. grapefruit)
44
You should Retest TSH & T4 (or FT4) in _____ after medication initiation
6-8 weeks
45
Management of Hyperthyroidism
* 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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