Endocrine and Rheumatological Conditions

Endocrine System Overview

  • The endocrine system acts as mission control, regulating vital functions through hormone release.

Thyroid Hormone Regulation

  • Hypothalamus: Releases thyrotropin releasing hormone (TRH).
  • Anterior Pituitary Gland: TRH stimulates the release of thyroid stimulating hormone (TSH).
  • Thyroid: TSH signals the thyroid to produce T3 and T4.
  • Function: T3 and T4 regulate metabolism.

Hypothyroidism

  • Definition: Too little active thyroid hormones.
  • Primary Hypothyroidism: Malfunctioning thyroid gland.
  • Most Common Cause: Hashimoto's thyroiditis (autoimmune).
  • Signs and Symptoms:
    • Slow metabolism.
    • Weight gain.
    • Cold intolerance.
    • Constipation.
    • Hair loss.
    • Brittle nails.
    • Slow reflexes.
    • Bradycardia.
    • Heavier, irregular menstrual periods.
    • Facial swelling and fluid retention.
    • Possible goiter.
  • Labs:
    • High TSH.
    • Low T3 and T4.
  • Normal TSH range: 0.5 - 5
  • Initial Lab: TSH (cost-effective).
  • Management:
    • Levothyroxine (Synthroid): Synthetic T4.
    • Cardiac Side Effects: Start low, go slow, especially in older adults and those with cardiac history.
    • Standard Daily Dose: 50 - 200 \mu g per day.
    • Older Adults Starting Dose: 25 - 50 \mu g per day.
    • Cardiovascular History Starting Dose: 12.5 - 25 \mu g per day.
    • Recheck TSH levels at 6 weeks.

Hyperthyroidism

  • Definition: Oversecretion of active thyroid hormone.
  • Most Common Cause: Graves' disease (autoimmune).
  • Labs:
    • Elevated T3 and T4.
    • Decreased TSH.
  • Signs and Symptoms:
    • Weight loss.
    • Heat intolerance.
    • Diarrhea.
    • Blurry or double vision.
    • Tremors and palpitations.
    • Amenorrhea.
    • Possible goiter.
  • Management:
    • Managed by endocrinology.
    • Medications: Propylthiouracil (PTU) or methimazole (Tapazole).
    • Other options: Radioiodine therapy or surgery.
    • Beta blockers: Alleviate palpitations, tachycardia, and anxiety.
  • Pregnancy:
    • Surgery and radioiodine are inappropriate.
    • First trimester: PTU (less placental crossing).
    • Second trimester: Methimazole.
    • Mnemonic: P (Pregnancy) and PTU comes first.

Parathyroid Gland

  • Location: Posterior to the thyroid.
  • Function: Secretes parathyroid hormone (PTH), controlling calcium and phosphate levels.
  • Calcium Importance: Bone, nerve, and muscle health.
  • Hyperparathyroidism: Too much PTH, leading to elevated calcium.
  • Clinical Practice: Check PTH if abnormal calcium levels are present.
  • Referral: Endocrine or ENT referral for suspected parathyroid dysfunction.
  • Bonus Tidbit: Elevated calcium may indicate underlying malignancy.

Adrenal Glands

  • Location: On top of the kidneys.
  • Function: Hormone production for stress response, blood pressure, electrolyte balance, and androgen development.

Addison Disease (Primary Adrenal Insufficiency)

  • Definition: Underproduction of cortisol and other vital hormones.
  • Cause: Autoimmune.
  • Mnemonic: Add more steroids.
  • Signs and Symptoms:
    • Weakness.
    • Diarrhea and vomiting.
    • Abdominal pain.
    • Muscle pain.
    • Amenorrhea.
    • Skin hyperpigmentation.
  • Labs:
    • Hyponatremia.
    • Hyperkalemia.
  • Treatment:
    • Steroid replacement.
    • Emergency medical kit with steroids.
    • Medical alert bracelet.
  • Acute Adrenal Crisis: Life-threatening if steroids are not administered during illness, injury, surgery, or stress.

Cushing Syndrome and Disease

  • Cushing's Syndrome: Excessive cortisol, typically from long-term steroid use.
  • Cushing's Disease: Cushing's syndrome caused by a benign pituitary tumor secreting excess ACTH.
  • Labs:
    • High cortisol levels.
    • Hypokalemia.
    • Hypernatremia.
    • Hyperglycemia (impaired glucose tolerance).
  • Signs and Symptoms:
    • Moon face.
    • Buffalo hump.
    • Truncal obesity.
    • Purple striae.
  • Treatment:
    • Depends on the cause; surgery if ACTH-secreting tumor is present.

Pheochromocytoma

  • Definition: Rare tumor on adrenal glands secreting epinephrine and norepinephrine (catecholamines).
  • Catecholamines: Regulate fight or flight response.
  • Signs and Symptoms:
    • Hypertension.
    • Headaches.
    • Perspiration.
    • Heart palpitations.
    • Anxiety.
  • Diagnosis:
    • Difficult due to episodic symptoms.
  • Treatment:
    • Surgery.
    • Management of blood pressure and dysrhythmias pre-surgery.

Rheumatological Conditions

  • Definition: Inflammatory, often autoimmune disorders where the body attacks itself.

Lupus

  • Definition: Inflammatory autoimmune condition affecting many body systems.
  • Nickname: The great imitator.
  • Demographics: Common in younger women of childbearing age.
  • Signs and Symptoms:
    • Joint pain.
    • Fever.
    • Malaise.
    • Butterfly-shaped malar rash (spares nasolabial folds).
    • Sun sensitivity with rash on exposed areas.
  • Organ Involvement: Kidneys (can lead to end-stage kidney disease).
  • Diagnosis:
    • Antinuclear antibody (ANA) test.
    • Note: ANA can be positive in other diseases.
  • Referral:
    • Positive ANA and clinical findings warrant referral to rheumatology.

Sjogren's Syndrome

  • Definition: Autoimmune condition causing dryness of eyes and mouth (dysfunction of salivary and lacrimal glands).
  • Mnemonic: S for Sahara (dry eyes and mouth).
  • Treatment:
    • Supportive methods: artificial tears, sugar-free mints and gum, frequent fluid intake.