unit 3,4,5

• Endocrine system


  A network of glands throughout your body that make hormones
• Hormones


  Chemical messengers that travel through your bloodstream to your organs, tissues, and cells and regulate different bodily functions
• Endocrine disorders discussed


  • Hypothyroidism
  • Hyperthyroidism
  • Diabetes mellitus
• Thyroid gland


  • Butterfly-shaped gland located in the front of your lower neck, just below your Adam's apple
  • Produces thyroid hormones (T4 and T3) that affect nearly every cell in your body
• Functions influenced by thyroid hormones

  • Heart rate
  • Breathing
  • Digestion
  • Muscle control
  • Bone health
  • Mood
  • Weight
  • Body temperature
• Thyroxine (T4)


  Thyroid hormone containing four iodine atoms, about 90% of thyroid hormone output
• Triiodothyronine (T3)


  Thyroid hormone containing three iodine atoms, about 10% of thyroid hormone output
• Common thyroid function tests


  • Thyroid-stimulating hormone (TSH)
  • Thyroxine (T4)
  • Free thyroxine (FT4)
  • Triiodothyronine (T3)
• TSH test


  Measures the level of TSH in your blood, the most sensitive indicator of thyroid function
• T4 test


  Measures the level of total thyroxine in your blood, the main thyroid hormone produced by the thyroid gland
• FT4 test


  Measures the level of free thyroxine in your blood, the active form of T4 that can enter your cells and affect your metabolism
• T3 test


  Measures the level of triiodothyronine in your blood, a more potent form of thyroid hormone than T4
• Thyroid function tests may be ordered if you are experiencing symptoms of a thyroid disorder or to monitor the effectiveness of treatment for a thyroid disorder
• Hypothyroidism


  A condition where the thyroid gland doesn't produce enough thyroid hormone, slowing down metabolism
• Causes of hypothyroidism


  • Hashimoto's thyroiditis
  • Treatment for an overactive thyroid
  • Thyroiditis
  • Iodine deficiency
  • Congenital hypothyroidism
  • Pituitary or hypothalamus problems
• Symptoms of hypothyroidism


  • Fatigue
  • Weight gain
  • Cold intolerance
  • Dry skin
  • Hair loss
  • Constipation
  • Irregular periods
• Types of hypothyroidism


  • Primary hypothyroidism
  • Secondary hypothyroidism
  • Tertiary hypothyroidism
• Primary hypothyroidism


  The most common type, occurs when the thyroid gland itself isn't producing enough thyroid hormone
• Secondary hypothyroidism


  A less common type that occurs when the pituitary gland doesn't produce enough thyroid-stimulating hormone (TSH)
• Tertiary hypothyroidism


  A rare type that occurs when the hypothalamus doesn't produce enough thyrotropin-releasing hormone (TRH)
• Diagnosis of hypothyroidism


  Blood tests (TSH, T4 levels)
• Normal ranges for thyroid function tests

  • TSH: 0.5 to 5.0 mIU/L for adults
  • T4: 0.7 to 1.9 ng/dL for adults
  • T3: 80 to 220 ng/dL for adults
  • FT4: 0.7 to 1.9 ng/dL for adults
• Normal ranges for thyroid function tests can vary slightly depending on the specific lab performing the test and age
• Medications that can affect thyroid function tests

  • Increase TSH: Dopamine agonists, steroids, somatostatin analogs, amiodarone, psychiatric medications
  • Decrease TSH: Thyroid hormone replacement therapy, dopamine antagonists
  • Increase T4 and FT4: Estrogens, steroids
  • Decrease T4 and FT4: High doses of biotin
  • Affect T3 levels: Fasting, severe illness, androgens, glucocorticoids
• Levothyroxine (Synthroid, Levothroid)


  Synthetic thyroid hormone used to replace missing hormone in hypothyroidism, long-term treatment taken daily on an empty stomach
• LT3 (liothyronine)


  Active form of thyroid hormone that directly affects cells throughout the body
• LT4 (levothyroxine)


  Inactive form of thyroid hormone that is converted to LT3 in the liver and other tissues, the primary hormone used in most thyroid replacement medications
• Balanced diet and regular exercise can help manage weight and energy levels in hypothyroidism
• Hyperthyroidism


  An overproduction of thyroid hormone, causing the body's processes to speed up
• Causes of hyperthyroidism


  • Graves' disease (autoimmune)
  • Thyroid nodules
  • Excess iodine intake
• Symptoms of hyperthyroidism


  • Weight loss
  • Increased appetite
  • Fatigue
  • Anxiety
  • Irritability
  • Rapid heartbeat
  • Heat intolerance
  • Diarrhea
  • Frequent urination
  • Bulging eyes (Graves' disease)
• Diagnosis of hyperthyroidism


  Blood tests (TSH, T4 levels), radioactive iodine uptake test, thyroid scan
• Pharmaceutical treatments for hyperthyroidism

  • Antithyroid medications (Methimazole, Propylthiouracil)
  • Beta-blockers (Propranolol, Atenolol)
  • Radioactive iodine therapy
  • Thyroid surgery
• Methimazole


  Preferred antithyroid medication, can be taken once, twice, or three times a day
• Propylthiouracil (PTU)


  Antithyroid medication that may be used in specific situations, such as during pregnancy or if you cannot tolerate methimazole, typically taken two or three times a day
• How antithyroid medications work

  They interfere with the incorporation of iodine into thyroid hormones
• Treatment goal for antithyroid medications

  To bring your thyroid hormone levels back into the normal range and alleviate symptoms of hyperthyroidism
• Lol)


  Don't affect thyroid function but manage symptoms like rapid heart rate and tremors
• Radioactive iodine therapy


  • Destroys overactive thyroid tissue
  • May require lifelong thyroid hormone replacement later
• Thyroid surgery


  • In severe cases, removal of part or all of the thyroid gland
  • Requires lifelong thyroid hormone replacement therapy