Chapter 66 starting with Hypothyroidism Flashcards
What is hypothyroidism?
Clinical syndrome by deficiency of thyroid hormones.
What effect does hypothyroidism have on infants and children?
It causes retardation of growth and development and may results in permanent motor and mental retardation.
What are some congenital causes of hypothyroidism?
- Agenesis- complete absence of thyroid tissue)
- Dysgenesis- ectopic or lingual thyroid gland
- Hypoplastic thyroid
- Congenital pituitary diseases.
What is adult-onset hypothyroidism?
Results in a slowing of metabolic processes and is typically reversible with treatment.
What are the two divisions of hypothyroidism?
Primary- thyroid failure
Secondary- hypothalamic or pituitary deficiency
What is the most common cause of hypothyroidism in adults?
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.
What are some iatrogenic (caused by medication, medical treatment) causes of hypothyroidism?
Iodine therapy, thyroidectomy, treatment with lithium or amiodarone.
Iodine deficiency or excess can also cause hypothyroidism.
Clinical presentation of children/infants with hypothyroidism.
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.
Clinical presentation of adults with hypothyroidism.
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.
Characteristics of severe untreated hypothyroidism in an adult are what?
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
List the subtypes (with causes) of Primary hypothyroidism.
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
List the causes (subtypes) of secondary hypothyroidism
Hypothalamic Dysfunction: Neoplasms, TB, Sarcoidosis, Langerhans cell histocytosis, Hemochromatosis, radiation treatment.
Pituitary Dysfunction: Neopasms, pituitary surgery, Idiopathic hypopituitarism, Cushing’s syndrome, Radiation treatment.
Common laboratory abnormalities in patients with PRIMARY hypothyroidism?
- Elevated serum TSH
- low total and free T4
Hypothyroidism is often associated with hyper cholesterol and elevated creatine.
Common laboratory abnormalities in patients with SECONDARY hypothyroidism
- low plasma thyroid hormone levels
- low or low/normal TSH should be suspected of having secondary hypothyroidism (i.e. pituitary failure).
A lady walks into your office complaining of irregular menstrual cycles and body aches, what could this be an early sign of?
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.
What is the initial treatment for patients with Hypothyroidism?
L-thyroxine
This drug is T4 and is converted in the periphery to the active hormone T3.
What is the 1/2 life of L-thyroxine, and what is the typical dosing?
- 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.
T/F Serum TSH levels should be checked 10 weeks after dose adjustment.
FALSE. These levels should be checked at 6 weeks. The optimal level should be between .5 - 2 mU/L.
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?
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.
What is an enlargement of the thyroid gland?
Goiter
What are the different types of goiters?
- Euthyroid (simple goiter)
- hyperthyroid (toxic nodular goiter or Graves disease)
- hypothyroid (nontoxic goiter or Hashimoto thyroiditis)
A patient with a smooth, symmetrical gland, often with a bruit and hyperthyroidism is suspicious for what disease?
Graves disease.
A nodular thyroid gland on exam and lab values showing positive antithyroid antibodies associated with hypothyroidism is likely what disease?
Hashimoto’s thyroiditis
When is the only time surgery is indicated in regards to a goiter?
For nontoxic goiter ONLY if obstructive symptoms develop or substantial substernal extension is present.
