Hypothyroidism - NUR 425 Week 6 Notes PDF

**[Hypothyroidism]** - Occurs because of dec amounts of thyroid hormone in the blood  - Multiple possible causes  - Primary  - Destruction of the thyroid tissue or defective hormone synthesis  - Secondary  - Related to pituitary disease (dec secretion of TSH) or...

**[Hypothyroidism]** - Occurs because of dec amounts of thyroid hormone in the blood  - Multiple possible causes  - Primary  - Destruction of the thyroid tissue or defective hormone synthesis  - Secondary  - Related to pituitary disease (dec secretion of TSH) or hypothalamic dysfunction (dec secretion of TRH)  - Outside of thyroid but effects how hormone is produced  ***Causes of hypothyroidism*** - Iodine deficiency is the most common cause of hypothyroidism WW (and is a primary cause)  - Most common cause in Canada: **Hashimoto's thyroiditis ** - Autoimmune disease which can destroy the thyroid gland  - Atrophy: may be due to treatment for hyperthyroidism, such as surgical removal of the thyroid gland or use of Radioactive Iodine Therapy  ***Clinical manifestations of hypothyroidism *** - Can occur suddenly such as with a thyroidectomy  - Typically appears slowly over months to years  - Usually first present as fatigue and lethargy  - Dec cardiac output and reduced cardiac contractility  - Personality changes, impaired and/or slowed speech, decreased initiative  - Goiter - body attempts to signal thyroid to produce more hormones  - Anemia  - Dyslipidemia - elevated cholesterol  - Decreased GI motility - constipation or abdominal discomfort  - Menorrhagia - increased bleeding due to hormone imbalance  - Symptoms of cold intolerance, hair loss, dry coarse skin, brittle nails, hoarseness, muscle weakness, and weight gain may be due to decreased metabolic rate  ***Myxedema*** - Longstanding hypothyroidism may lead to myxedema  - In myxedema, there is an abnormal accumulation of substances (hydrophilic mucopolysaccharides) in the dermis and other tissues, which leads to mucinous edema  - Myxedema presents with puffiness, periorbital edema and a mask-like affect  ***Hypothyroidism complication: Myxedema coma*** - Rare, life-threatening condition  - Mental sluggishness, drowsiness & lethargy proceed to decreased LOC and coma  - May be precipitated by infection, trauma, drugs, exposure to drugs  - Manifestations: subnormal temperature, hypotension & hypoventilation  - Treatment includes: addressing precipitating factors, supporting vital functions (ABCs), IV thyroid hormone replacement, supportive care (e.g. temperature management, fluid and electrolyte management)  ***Hypothyroidism: Evaluation*** - History and physical assessment  - TSH  - Used to screen for hypothyroidism and to monitor thyroid replacement therapy  - Inc with primary hypothyroidism  - May be decreased with secondary hypothyroidism  - Free T4 -  decreased (more important in assessment and management than fT3)  - fT4 directly shows if thyroid is working properly  - Free T3 - decreased  ***Pharmacotherapy for Hypothyroidism *** - Goal is to restore euthyroid state  - Oral levothyroxine (synthroid)  - Synthetic preparation of T4 (thyroxine)  - Usually started at lower dose and increased slowly every 4-6 weeks according to lab reports and AEs  - Need to assess for cardiac manifestations such as chest pain and arrhythmias due to increase in myocardial oxygen demand  - **Levothyroxine** - Administered on empty stomach to ensure optimal absorption  - Treatment is usually life-long  - With dose changes, must check TSH level in 4-6 weeks  - **Signs of levothyroxine toxicity ** - Orthopnea, dyspnea, tachycardia, palpitations, insomnia - Need for management of hypothyroidism during pregnancy  - Have increased metabolic needs especially in first trimester