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Endocrinology - Chapters > Chapter 66 starting with Hypothyroidism > Flashcards

Chapter 66 starting with Hypothyroidism Flashcards

1
Q

What is hypothyroidism?

A

Clinical syndrome by deficiency of thyroid hormones.

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2
Q

What effect does hypothyroidism have on infants and children?

A

It causes retardation of growth and development and may results in permanent motor and mental retardation.

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3
Q

What are some congenital causes of hypothyroidism?

A
  1. Agenesis- complete absence of thyroid tissue)
  2. Dysgenesis- ectopic or lingual thyroid gland
  3. Hypoplastic thyroid
  4. Congenital pituitary diseases.
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4
Q

What is adult-onset hypothyroidism?

A

Results in a slowing of metabolic processes and is typically reversible with treatment.

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5
Q

What are the two divisions of hypothyroidism?

A

Primary- thyroid failure

Secondary- hypothalamic or pituitary deficiency

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6
Q

What is the most common cause of hypothyroidism in adults?

A

autoimmune thyroiditis AKA Hashimoto thyroiditis

FYI: this can be an isolated condition, or this can indicate polyglandular autoimmune syndrome (PGA). This is a condition when immune dysfunction affects two or more endocrine glands and other non-endocrine immune disorders are present. One will have Hashimoto along with DM, adrenal insufficiency, gonadal failure…etc.

The book barely mentions this, but it is likely good to know.

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7
Q

What are some iatrogenic (caused by medication, medical treatment) causes of hypothyroidism?

A

Iodine therapy, thyroidectomy, treatment with lithium or amiodarone.

Iodine deficiency or excess can also cause hypothyroidism.

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8
Q

Clinical presentation of children/infants with hypothyroidism.

A

Congenital hypothyroidism might present with:

  • feeding problems
  • hypotonia (state of low muscle tone)
  • inactivity
  • edematous face and hands
  • learning disabilities
  • delayed bone age
  • delayed puberty
  • short stature

THESE typically depend on the age of onset and severity of thyroid deficiency.

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9
Q

Clinical presentation of adults with hypothyroidism.

A

Hypothyroidism typically develops gradually in adults. Pt’s often complain of the following:

  • fatigue
  • lethargy
  • gradual weight gain
  • DELAYED RELAXATION PHASE of deep tendon reflexes (hung-up reflexes) is a valuable clinical sign of SEVERE hypothyroidism. ex.a deep tendon reflex in which, after a stimulus is given and the reflex action takes place, the limb slowly returns to its neutral position.
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10
Q

Characteristics of severe untreated hypothyroidism in an adult are what?

A

Myxedema coma- loss of brain function as a result of severe, longstanding low level of thyroid hormone in the blood (hypothyroidism).

  • hypothermia
  • extreme weakness
  • stupor
  • hypoventilation
  • hypoglycemia
  • hyponatremia
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11
Q

List the subtypes (with causes) of Primary hypothyroidism.

A

Autoimmune- hashimoto’s, part of PGA (polyglandular failure syndrome)

Iatrogenic- Iodine therapy, thyroidectomy

Drug Induced- Iodine deficiency, iodine excess, Lithium, Admiodarone, antithyroid drugs.

Congenital- Thyroid agenesis, Thyroid dysgenesis, Hypoplastic thyroid

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12
Q

List the causes (subtypes) of secondary hypothyroidism

A

Hypothalamic Dysfunction: Neoplasms, TB, Sarcoidosis, Langerhans cell histocytosis, Hemochromatosis, radiation treatment.

Pituitary Dysfunction: Neopasms, pituitary surgery, Idiopathic hypopituitarism, Cushing’s syndrome, Radiation treatment.

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13
Q

Common laboratory abnormalities in patients with PRIMARY hypothyroidism?

A
  • Elevated serum TSH
  • low total and free T4

Hypothyroidism is often associated with hyper cholesterol and elevated creatine.

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14
Q

Common laboratory abnormalities in patients with SECONDARY hypothyroidism

A
  • low plasma thyroid hormone levels

- low or low/normal TSH should be suspected of having secondary hypothyroidism (i.e. pituitary failure).

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15
Q

A lady walks into your office complaining of irregular menstrual cycles and body aches, what could this be an early sign of?

A

Hypothyroidism.

explanation: The book reports the initial manifestations of hypothyroidism are subtle, the most common overlooked symptoms are irregular menstrual cycles, myalgia, arthralgias.

Any patient with two or more of the signs/symptoms of hypothyroidism should be tested for the disease.

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16
Q

What is the initial treatment for patients with Hypothyroidism?

A

L-thyroxine

This drug is T4 and is converted in the periphery to the active hormone T3.

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17
Q

What is the 1/2 life of L-thyroxine, and what is the typical dosing?

A
  • The 1/2 life is 8 days.
  • The drug is typically given once daily (qd).

FYI: In cardiac and older adults, you start at a lower dose than you would a healthy individual.

18
Q

T/F Serum TSH levels should be checked 10 weeks after dose adjustment.

A

FALSE. These levels should be checked at 6 weeks. The optimal level should be between .5 - 2 mU/L.

19
Q

Your patient comes into the ER unconscious, hypoventilating and hypothermic. You draw labs and notice a lo sodium levels. What does condition does this patient have, and what is the appropriate plan of treatment?

A

The condition: Myxedema coma (cause is from untreated, severe hypothyroidism).

Treatment: IV L-thyroxine 300-400 mg. This is the loading dose. You will follow it with 50mg of daily along with hydrocortisone (IV, 3x a day).

You will also treat her hypothermia with warm blankets, and treat the low Na levels.

20
Q

What is an enlargement of the thyroid gland?

A

Goiter

21
Q

What are the different types of goiters?

A
  • Euthyroid (simple goiter)
  • hyperthyroid (toxic nodular goiter or Graves disease)
  • hypothyroid (nontoxic goiter or Hashimoto thyroiditis)
22
Q

A patient with a smooth, symmetrical gland, often with a bruit and hyperthyroidism is suspicious for what disease?

A

Graves disease.

23
Q

A nodular thyroid gland on exam and lab values showing positive antithyroid antibodies associated with hypothyroidism is likely what disease?

A

Hashimoto’s thyroiditis

24
Q

When is the only time surgery is indicated in regards to a goiter?

A

For nontoxic goiter ONLY if obstructive symptoms develop or substantial substernal extension is present.

25
Q

What is the treatment for hypothyroid goiters?

A

Thyroid hormone at a dose that normalizes TSH

26
Q

What are benign thyroid nodules, typically felt as a single nodule on exam?

A

Follicular adenomas, colloid nodules, benign cysts, nodular thyroiditis.

27
Q

Is a child with previous head and neck radiation exposure at an increase risk for thyroid cancer over a child without radiation exposure?

A

YES The major etiologic factor for thyroid cancer is childhood or adolescent exposure to head and neck radiation.

FYI: Patients with history of irradiation should have a baseline thyroid US and their thyroid palpated every 1-2 years.

28
Q

Is a thyroid nodule <1.5 cm compatible with carcinoma?

A

NO. Anything >1.5cm is compatible with neoplasia and should undergo FNA.

75% of all FNAs are benign lesions. 5% are malignant.

FYI: Follicular neoplasms, however cannot be diagnosed as benign or malignant by FNA.

29
Q

Name the 5 types of Thyroid Cancers

A
  1. Papillary
  2. Follicular
  3. Medullary
  4. Anaplastic
  5. Lymphoma (not so sure about this)
30
Q

What is the most common type of thyroid cancer?

A

Papillary.

  • Associated with local invasion and lymph node spread. Good prognosis. Typically seen in pts 40-80. Will typically undergo thyroidectomy.
31
Q

What is the most aggressive type of thyroid cancer?

A

Anaplastic.

  • Makes up 1% of thyroid cancers
  • Seen in patients ages 50-80.
  • Very aggressive
  • Rapidly causes pain, dysphagia and hoarseness.
  • POOR prognosis
32
Q

Is Medullary Thyroid Cancer more malignant than Follicular or Papillary carcinomas?

A

YES. It is multifocal and spreads locally and distally.

  • Can be sporadic or familial.
  • When familial it is inherited by autosomal dominant pattern.
33
Q

What are the T4 and T3 levels in a patient with subclinical hypothyroidism?

A

These are both normal or low normal.

The TSH is slightly elevated.

34
Q

Treatment for isolated papillary microcarcinoma?

A

Lobectomy may be performed for ISOLATED papillary carcinoma.

HOWEVER, most papillary or follicular tumors require thyroidectomy with central compartment lymph node dissection/modified neck dissection (with evidence of lateral lymph nodes).

35
Q

Your hott PA friend Holly just performed her first thyroidectomy in a patient with LOW-RISK, small carcinoma. What post surgery medication will she most likely give the pt?

A

Levothyroxine.

In patients with low-risk carcinomas, levothyroxine is sufficient to keep the TSH level in the low-normal or slightly suppressed range. Continue to follow up pt with neck US.

36
Q

Your bad ASS friend Stephanie just performed her first thyroidectomy on a pt with large lesions who is at risk for persistence or metastatic disease. What is the best plan of treatment following surgery?

A

Radioactive iodine is the first treatment pt should undergo. This will follow with sufficient levothyroxine administration to suppress serum TSH to subnormal levels. FREQUENT clinical US of neck are required. This will also be accompanied by measurement of serum thyroglobulin levels.

37
Q

When monitoring a patient’s thyroglobulin levels post thyroidectomy, what does a high level of thyroglobulin indicate?

A

This suggests recurrence of thyroid cancer.

38
Q

Which type of thyroid carcinoma is treated with isthmusectomy to confirm the diagnosis?

A

Anaplastic carcinoma.

The isthmusectomy is also performed in order to prevent tracheal compression, followed by palliative x-ray treatment.

39
Q

What are the most important prognostic factors for well-differentiated thyroid carcinomas?

A
  • Age at time of diagnosis
  • Sex of the patient

Men older than 40 years of age and women older than 50 years of age have higher reoccurrence and death rates than do younger patients.

40
Q

In patients with Subclinical hypothyroidism, what is the aim of treatment?

A

To normalize the TSH

41
Q

The term Subclinical hypothyroidism means what?

A

Suggests the absence of normal “hypothyroidism” symptoms but with raised TSH levels in the presence of normal thyroid hormones.

Endocrinology - Chapters (20 decks)

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