Chapter 49: Hypothyroidism Flashcards
Cite the effect of hypothyroidism on one’s metabolic rate.
It causes a general slowing of the metabolic rate
Compare primary and secondary classifications of hypothyroidism.
*Primary hypothyroidism is caused by destruction of thyroid tissue or defective hormone synthesis
*Secondary is caused by pituitary disease with decreased TSH secretion or hypothalamic dysfunction with decreased thyrotropin releasing hormone (TRH) secretion
*Hypothyroidism can be brief and related to thyroiditis or stopping thyroid hormone therapy
Cite 2 autoimmune conditions that cause atrophy of the thyroid gland.
*Iodine deficiency is the most common cause of hypothyroidism worldwide
*In the US the most common cause of primary hypothyroidism is atrophy of the thyroid gland
*This atrophy is the result of Hashimoto’s thyroiditis or graves disease
*These autoimmune diseases destroy the thyroid gland
Describe how the treatment of hyperthyroidism can lead to hypothyroidism.
*Hypothyroidism can develop after treatment for hyperthyroidism, specifically thyroidectomy or RAI therapy
*Drugs such as amiodarone, which contains iodine and lithium, which blocks hormone production, can cause hypothyroidism
Describe the general effects of hypothyroidism on major systems and daily activities: cardiovascular (7)
*Decreased cardiac contractility
*Decreased cardiac output
*Low exercise tolerance
*Shortness of breath on exertion
*High serum cholesterol and triglyceride levels
*Coronary atherosclerosis
*Anemia
Describe the general effects of hypothyroidism on major systems and daily activities: neuro 7
*fatigue
*Personality and mental changes
*Impaired memory
*Slowed speech
*Decreased initiative
*Somnolence
*Weight gain
Define myxedema, how it develops, and how it alters one’s appearance. (4)
*Pts with severe, long standing hypothyroidism may have myxedema
*Results from accumulation of hydrophilic mucopolysaccharides in dermis and other tissues
*Alters physical appearance – puffiness, facial and periorbital edema, mask like effect
*In the older adult it may be attributed to normal aging
myxedema common features 6
Dull, puffy skin. Coarse, sparse hair. Periorbital edema, prominent tongue.
Describe how myxedema coma can cause cardiac collapse and how it is treated. 5
*What it is: Mental sluggishness, lethargy, and drowsiness of hypothyroidism gets really bad essentially
*precipitated by things like infection or drugs like opioids and barbs →
*S/S: low temp, hypotension, hypoventilation
*Cardio collapse can result from hypoventilation, hyponatremia, hypoglycemia, and lactic acidosis
*For the patient to survive myxedema coma, vital functions must be supported and IV thyroid hormone replacement given
Cite the most reliable laboratory tests to assess thyroid function 4
*TSH and Free T4
*These values correlated with symptoms obtained from the history and physical examination confirm the diagnosis of hypothyroidism
*TSH high: defect is in the thyroid
*TSH low: defect is in the pituitary or the hypothalamus
Discuss other laboratory values that are helpful to determine hypothyroidism. 4
high cholesterol and triglycerides, anemia, increased creatinine kinase
Discuss the treatment goal of hypothyroidism; identify the drug of choice. 3
*Restore a euthyroid state as safely and rapidly as possible with hormone therapy
*A low calorie diet can promote weight loss or prevent weight gain
*Drug of choice: Levothyroxine (Synthroid). May take up to 8 weeks until full effects of hormone therapy are seen. It is usually life long.
Explain the rationale behind the need for lifelong management in the case of hypothyroidism.
*Educate that patient must not abruptly stop taking meds
*Some patients notice weight loss and are tempted to increase dosing to achieve a desired weight. Advise against this.
*Teach patient about unexpected side effects and when to report to HCP
*this is a chronic disease
