Chap 31 Thyroid and Antithyroid Drugs Flashcards
Thyroid Gland
Secretes three hormones essential for proper regulation of metabolism
Thyroxine (T4)
Triiodothyronine (T3)
Calcitonin
Parathyroid* gland is responsible for maintaining adequate levels of calcium* in the extracellular fluid
Thyroid* hormones regulate basal metabolic* rate, lipid* and carbohydrate metabolism.
They are essential for normal growth and development
They control* the heat-regulating system (thermoregulation in the brain)**
https://youtu.be/iNrUpBwU3q0
Hypothyroidism*: Deficiency in Thyroid Hormones
Primary: abnormality in the thyroid gland itself
Secondary: results when the pituitary gland is dysfunctional and does not secrete thyroid-stimulating hormone (TSH)
Tertiary: results when the hypothalamus gland does not secrete thyrotropin-releasing hormone, which stimulates the release of TSH
Congenital hypothyroidism
Hyposecretion of thyroid hormone during youth- cretinism
Low metabolic rate, retarded growth and sexual development, possible mental retardation
Hypothyroidism Symptoms**
Dry Hair*
Loss of eyebrow hair
puffy face
enlarged thyroid*
slow heatbeat*
arthritis
cold intolerance*
depression*
dry skin*
fatigue*
forgetfulness*
menstrual disorders*
infertility
muscle aches
weight gain*
constipation*
brittle nails*
Thyroid Replacement Drugs
Hypothyroidism is treated with thyroid replacement drugs
These drugs can be natural or synthetic in origin (natural thyroid preparations are derived from thyroid glands of cattle’s and hogs)- simply thyroid or thyroid desiccated.
Synthetic thyroid preparations are:
Levothyroxine** (Synthroid, Levoxyl)
Synthetic thyroid hormone T4* (chemically pure, 100% T4, predictable effects)
Drug of choice**, long half-life so administered once a day, oral and parenteral form, pregnancy category A, dosage monitored by thyroid function tests.
Liothyronine* (Cytomel)
Synthetic thyroid hormone T3
Liotrix (Thyrolar)**
Synthetic thyroid hormone T4 and T3 combined, 4:1 ratio
Orangutans Will Vomit On You Right Before They Become Large Proud Gorillas
Orange 25 mcg
White 50mcg
Violet 75mcg
Olive 88mcg
Yellow 100mcg
Rose 112mcg
Brown 125mcg
Turquoise 137mcg
Blue 150mcg
Lilac 175 mcg
Pink 200mcg
Green 300 mcg
Thyroid Replacement Drugs: *Adverse Effects
Adverse effects of thyroid medications are usually the result of overdose
Cardiac dysrhythmia** is the most significant adverse effect
May also cause:
Tachycardia, palpitations, angina, hypertension, insomnia, tremors, headache, anxiety, nausea, diarrhea, menstrual irregularities, weight loss, sweating, heat intolerance, fever, others
Interactions:* may enhance the activity of oral anticoagulants, dosage needs to be reduced; cholestyramine binds to thyroid hormone in GI tract, which possibly reduce the absorption of both drugs; decrease in digitalis levels.
Thyroid Replacement Drugs: Nursing Implications
Obtain baseline vital signs and weight (for comparative purposes)
Assess *T3, T4, and TSH** before and during drug therapy
Assess and document thoroughly patient history, medical problems, medications, drug allergies and physical exam
Cautious use is advised for those with cardiac disease.
Lifespan considerations: increased sensitivity of drugs in older adult patients (use decreased dosage)
During pregnancy, treatment for hypothyroidism should continue.
Fetal growth may be retarded if maternal hypothyroidism is untreated during pregnancy.
Adjust dosage every 4 weeks to keep TSH at the lower end of the normal range.
Teach patients the importance of alerting health care providers about other medication use.
Thyroid replacement medications may enhance activity of anticoagulants, patients with diabetes may need increased dosages of hypoglycemic medications & may decrease serum digoxin levels
Teach patients that therapeutic effects may take several weeks to occur.
Teach patients to take thyroid drugs once daily in the morning to decrease the likelihood of insomnia if taken later in the day.
Teach patients to take the medications at the same time every day (help maintain consistent blood levels) and not to switch brands without primary care provider approval.
Avoid** taking the thyroid replacement drugs with vitamins and supplements containing iron and /or calcium within 4 hr time frame; Antacids** and OTC preparations with iodine must be avoided
Iodized salt and iodine-rich foods, such as soybeans, tofu, turnips, high-iodine seafood and some breads should be avoided.
Hyperthyroidism*: Excessive Thyroid Hormones
Caused by several diseases
Graves’ disease** (common cause)
Plummer’s disease (rare)
Also called toxic nodular disease
Thyroid** storm (induced by stress or infection)
Severe and potentially life-threatening**
Exophthalmos(Bulging Eyes)**
Hyperthyroidism Symptoms
Intolerance to heat*
fine, straight hair
bulging eyes*
facial flushing
enlarged thyroid*
tachycardia*
increase systolic BP
breast enlargement
Weight Loss*
muscle wasting
Localized Edema*
Finger Clubbing*
Tremors*
increase in diarrhea*
Menstrual changes(Amenorrhea)*
Treatment of Hyperthyroidism
Radioactive iodine**
(I131) works by destroying the thyroid gland (ablation) https://youtu.be/04c4dXJRL1o
Surgery*
to remove all or part of the thyroid gland
Lifelong thyroid hormone replacement will be needed.
Antithyroid drugs: thioamide derivatives (decreases thyroid hormone)*
Methimazole (Tapazole)**
Propylthiouracil** (PTU)- generic only
Antithyroid Drugs Contraindication:
Drug allergy
Controversial to be used in pregnancy: according to FDA, propylthiouracil is to be used during the first trimester only and then methimazole is use for the remainder of the pregnancy (scalp abnormalities in fetus when methimazole is used).
Pregnancy category D
Adverse Effects: Most serious are Bone Marrow and Liver toxicity
Interactions: Additive leukopenic effects when taken in conjunction with other bone marrow suppressants and an *increase in activity of oral anticoagulants.**
Antithyroid Drugs
Methimazole and Propylthiouracil (PTU) act by inhibiting* the incorporation of iodine* molecules into the amino acid tyrosine, a process required to make the precursors of T3 and T4. By doing so, these drugs impede the formation of thyroid hormone.
PTU*
has added ability to inhibit* the *conversion of T4 to T3** in the peripheral circulation.
Overall effect is a decrease in the thyroid hormone level.
Normalization of the overall metabolic rate
Antithyroid Drugs: Nursing Implications
Assess vital signs for signs and symptoms of thyroid crisis or thyroid storm (muscle weakness, tremors, diarrhea, extreme sweating, palpitations, can progress to coma or cardiac failure)
PTU can be taken with meals to help decreased stomach upset.
Give at the same time each day to maintain consistent blood levels.
Never* stop these medications abruptly.**
Any fever, sore throat, mouth ulcers or sores, skin eruptions and bleeding/bruising should be reported to prescriber immediately (indicates liver or bone marrow toxicity).
LFTs and *CBC should be monitored *
Avoid use of iodized salt or eating shellfish (may alter drug effectiveness).
Report S/s of hypothyroidism
Monitor
Monitor for therapeutic*response.
Thyroid drugs: decreased symptoms of hypothyroidism, improved energy levels, improved mental* and physical* stamina
Antithyroid drugs: no evidence of hyperthyroidism
Monitor for adverse* effects.
Thyroid drugs: cardiac dysrhythmia**
Antithyroid drugs: leukopenia** (manifested as fever, sore throat, lesions)
