Medications for thyroid disorders: Nursing Pharmacology

Thyroid disorders can be broadly divided into two categories which are on opposite ends of a spectrum: hypothyroidism, which describes a decrease in the thyroid hormones; and hyperthyroidism, which describes an increase in the thyroid hormones.

Now, thyroid hormones include triiodothyronine, or T3 for short, and thyroxine, or T4, and both contain iodine. The synthesis of these hormones is stimulated by another hormone, called thyroid stimulating hormone or TSH for short, which is released by the pituitary gland.

Okay, so on one side of the spectrum, there’s hypothyroidism. This is treated with thyroid hormone replacement therapy, which involves medications to replace the reduced thyroid hormones.

These medications include levothyroxine, which is a synthetic form of T4, and liothyronine, which is a synthetic form of T3.

Both of these medications may be given orally or intravenously, and levothyroxine can be administered intramuscularly too.

Once administered, they bind to intracellular thyroid hormone receptors in tissue cells to mimic the actions of thyroid hormones, such as increasing the metabolic rate, body temperature and cardiac output.

Now, the most common side effects of thyroid hormone replacement therapy include headaches, insomnia, nervousness, as well as weight loss, excessive sweating, and heat intolerance.

Some clients may also experience cardiovascular side effects, such as tachycardia, palpitations, and even cardiac arrest.

Alright, now contraindications of thyroid hormone replacement therapy include thyrotoxicosis or a high level of thyroid hormones, as well as in clients with adrenal insufficiency, and those who had a recent myocardial infarction. Also, as a boxed warning, these medications should not be used as obesity treatment.

Now, on the other side of the spectrum, there’s hyperthyroidism. This is treated with antithyroid agents like methimazole and propylthiouracil, which are administered orally.

Once administered, these medications inhibit the synthesis of thyroid hormones by decreasing iodine use.

Side effects of antithyroid agents include headaches, enlarged thyroid gland or goiter, and gastrointestinal disturbances like nausea, vomiting, and diarrhea.

In addition, clients may develop hepatitis and jaundice. In fact, propylthiouracil has a boxed warning for being highly hepatotoxic, potentially causing severe liver injury and acute liver failure.

Other important side effects include lymphadenopathy, vasculitis, and nephritis, as well as blood dyscrasias such as leukopenia and thrombocytopenia.

Some clients may also develop a skin rash, urticaria, and pruritus, as well as arthralgia, myalgia, and nocturnal muscle cramps.

Finally, contraindications of antithyroid agents include pregnancy and breastfeeding. However, as a boxed warning when absolutely necessary, propylthiouracil can be used during the first trimester of pregnancy.

Finally, antithyroid agents should be used with caution in infants, as well as in clients with bone marrow depression, bleeding disorders, or leukopenia.

Alright, when caring for a client with a thyroid disorder, first ask your client about their symptoms, such as changes in energy level, appetite, physical appearance, weight, and degree of heat or cold tolerance.