Pharma W7 Part 3: Thyroid Gland

Study Notes

The thyroid gland is located across the larynx (voice box).
It produces three essential hormones for metabolism: T4 (Thyroxine), T3 (Triiodothyronine), and Calcitonin.
Dietary iodine is necessary for the synthesis of T3 and T4 hormones.
T3 and T4 are stored in the thyroid until released into circulation by the thyroid-stimulating hormone (TSH).
Thyroid hormones are crucial for energy metabolism. They energize the body by increasing metabolism and improving nutrient and oxygen utilization, enhancing energy levels.

Hyperthyroidism is characterized by excess T3 and T4 secretion, resulting in hypermetabolism.
- Symptoms include: increased heart rate, weight loss, sweating, and difficulty sleeping.
- A common cause of hyperthyroidism is Graves' disease, an autoimmune disease.
- Exophthalmos (bulging eyes) is sometimes seen in Graves' disease.
Hypothyroidism is characterized by low T3 and T4 secretion, resulting in hypometabolism.
- Symptoms include: fatigue, weight gain, cold intolerance, and depression.
- Myxedema is a severe form of hypothyroidism.
- Remember the mnemonic: "Hyper can't tolerate heat, Hypo can't tolerate cold."

Antithyroid drugs:
- Thiamazole and Propylthiouracil (PTU) are commonly used.
- Important: Take these drugs with food to improve tolerance.
- Avoid: foods high in iodine (seafood, soy sauce, tofu, iodized salt).
- Serious effects: liver and bone marrow toxicity should be monitored.
Iodine compounds:
- Radioactive iodine can be used for thyroid gland ablation (destruction).
- Potassium iodine decreases blood supply to the thyroid gland.
Thyroidectomy (surgical removal of the thyroid gland) requires lifelong thyroid hormone replacement to prevent hypothyroidism.

Thyroid replacement drugs:
- Levothyroxine (Synthroid) is the synthetic T4.
- Take it once daily in the morning to decrease the risk of insomnia.
- MOA: Levothyroxine works similarly to endogenous thyroid hormones.
- Indications: Used to replace thyroid hormones when the gland is removed, destroyed by radioactive iodine, or unable to effectively use iodine.
- Goal: Achieve euthyroidism (normal thyroid levels).
- Adverse effects: Cardiac dysrhythmias.
- Contraindications: Acute myocardial infarction (MI) and hyperthyroidism.

Maintaining hypothyroidism treatment during pregnancy is crucial.
This prevents complications like miscarriage and fetal growth restriction.
Regular monitoring of TSH levels is essential for both maternal and fetal health.

Consistent medication administration:
- Take at the same time each day for consistent blood levels.
- Don't switch brands without approval.
Discontinuation of medication: Do not stop taking the medications abruptly.
Unusual symptoms: Monitor for reports of chest pain or heart palpitations.
Therapeutic effects: It may take several weeks for therapeutic effects to occur.
Monitoring:
- Liver and bone toxicity (hyperthyroidism – anti thyroids)
- Cardiac dysrhythmias (hypothyroidism – thyroid replacement).