212B Thyroid & Parathyroid Disorders Overview

Thyroid & Parathyroid Disorders: Basic Concepts

• The pituitary gland is the "master gland" controlling other glands.
• The hypothalamus sends messages to the pituitary gland, which then directs other organs like the thyroid and adrenal cortex.

Endocrine Assessment

• Assess current and past medical history, including work location and recent events like accidents.
• Crucial to evaluate blood levels and urinalysis.

Endocrine Treatments

• Hormone replacement therapy is a common treatment.
• Suppressing hormone overproduction is another therapeutic approach.

Thyroid Gland

• Shaped like a butterfly, located in the neck.
• Requires iodine for hormone synthesis; dietary iodine is essential.
• High iodine intake can temporarily reduce thyroid hormone production as a protective mechanism (e.g., potassium iodide).
• The thyroid produces hormones triiodothyronine (T3) and thyroxine (T4).
• Thyroxine (T4) regulates metabolism.
• Thyroid disorders are more prevalent in women compared to men.

Goiter

• Enlargement of the thyroid gland
• May be associated with excess thyroid-stimulating hormone (TSH) or low iodine levels.

Hypothyroidism

• Low thyroid levels (insufficient T3 and T4).

• Common causes include Hashimoto's thyroiditis (autoimmune disorder), medications, genetics, postpartum thyroiditis, or congenital conditions.

• Symptoms: cold intolerance, weight gain, lethargy, fatigue, memory deficits, and poor attention span.

• Other symptoms include muscle cramps, constipation, decreased fertility, and brittle nails.

• Important to note that reduced LDL receptors lead to hyperlipidemia and elevated carotene levels can cause yellow/orange skin. Also, decreased renal function can increase susceptibility to drug toxicity due to impaired kidney filtration.

Diagnosis and Treatment

• Primary: High TSH, low free T3 & T4; thyroid is not responding properly to TSH, so hormone replacement therapy (e.g., levothyroxine) is vital.
• Secondary: Low TSH, low free T3 & T4; pituitary issue; treatment focuses on removing any tumor causing the issue.
• Hashimoto's Thyroiditis: levels gradually decline.

Hyperthyroidism

• Elevated free T3 & T4 levels.
• A common cause is Graves' Disease, where antibodies bind to and activate thyroid-stimulating hormone (TSH) receptors, causing the gland to enlarge and overproduce thyroid hormones.
• Other causes include subacute thyroiditis, postpartum thyroiditis, thyroid adenoma (tumors), excessive TSH, toxic multinodular goiter (TMG), or excessive iodine ingestion (Jod Basedow Syndrome).
• Symptoms include nervousness, insomnia, sensitivity to heat, weight loss, enlarged thyroid gland, increased heart rate, anxiety, and tremors. Exophthalmos (protruding eyes) and Graves ophthalmopathy(inflammation of the eye tissues) may also be observed.

Thyroid Medications

• Levothyroxine (Synthroid): replacement therapy for hypothyroidism (low thyroid hormone).
• Propylthiouracil (PTU) and Methimazole (Tapazole): antithyroid agents used to treat hyperthyroidism (high thyroid hormone).
• Radioactive iodine (RAI): used to treat hyperthyroidism by destroying part of the thyroid gland.

Parathyroid Gland and Disorders

• Located within the thyroid gland.
• Secretes parathyroid hormone (PTH), which regulates calcium levels in the blood. Low calcium levels trigger PTH secretion, which activates bone reabsorption and intestinal calcium absorption by the kidneys.
• Hypoparathyroidism: Rare; often due to inadvertent damage during thyroid surgery; symptoms mirror hypocalcemia.
• Hyperparathyroidism: Presence of a parathyroid tumor increases PTH and calcium levels, requiring surgical removal of the tumor to restore calcium balance.

Thyroid Nodules

• Can be symptomatic or asymptomatic.
• Single nodules may warrant further screening for potential cancerous growths.
• Multiple nodules often indicate benign conditions.
• Ultrasound, needle biopsy, and scans (hot, warm, or cold nodules) help identify potential problems.

Thyrotoxic Crisis (Thyroid Storm)

• Severe hyperthyroid condition with exaggerated metabolic effects triggered by stress, infections, surgery, trauma, medication interactions.
• Requires quick treatment to reduce thyroid hormone production, slow heart rate, and support overall body function.

Case Study Notes

• Antithyroid Agents: Administer medications at regular intervals, monitor patient response via blood tests, and watch for adverse effects (e.g., iodism, liver toxicity).
• Calcitriol: Monitor for GI effects (metallic taste, nausea, etc.), CNS effects (weakness, headache), and liver or kidney (renal) effects.
• Levothyroxine: crucial for replacing thyroid hormone for hypothyroidism.
• Children: thyroid and parathyroid considerations include monitoring growth and development, adjusting medication doses according to age, and closely tracking serum calcium levels.

This quiz covers basic concepts related to thyroid and parathyroid disorders, including the role of the pituitary gland and hypothalamus. It discusses the assessment and treatment options for endocrine disorders, such as hormone replacement therapy and dietary considerations for thyroid health.