ePathoPlusPage

Home

Lectures

Features

Plus

 

 

Thyroid and Adrenal

Outline

Thyroid
A. Review of Anatomy and Physiology

1. Diagram of Hypothalamus- Pituitary- Thyroid Interactions

2. thyroid gland made up of 2 lobes connected by isthmus,

3. synthesizes 3 hormones

    a. thryroxine (T4) = over 95% of circulating hormone

    b. triiodothyrionine (T3) = 5 % of circulating hormone

    c. thyrocalcitonin - decreases level of CA in blood by inhibiting resorption of calcium from bones (antagonizes effect of PTH )

4.Role of TSH

    a. released by posterior pituitary (in turn regulated by hypothalamus)         (negative feedback mechanisms)

    b. increases size and number of follicular cells

    c. increases ability of follicular cells to take up iodine

    d. promotes breakdown of thyroglobulin

5. parathyroid gland

    a. action of Parathyroid Hormone (PTH)

        1. increases bone resorption of calcium (increases level of Ca and phosphate in bloodstream)

        2. increases calcium absorption from GI tract

        3. decreases urinary excretion of calcium

        4. increases urinary excretion of phosphate

B. Goiters (enlargement of thyroid)

    a. simple - due to hypothyroidism

        1.. iodide deficiency

        2... congenital metabolic effects

        3.. blocking of hormone sysnthesis by chemical agents

    b. nodular vs diffuse

    c. toxic- cause hyperthyroidism

C. Cancer of Thyroid

    a. papillary (most common)- slow growing tumor

    b. follicular - involves blood vessels

    c. medullary- often occurs as a result of MEN (multiple endocrine              neoplasia)

D. Thyroiditis (inflammation of the thyroid)

    a. acute

    b. subacute

    c. chronic (Lymphocytic, Hashimoto’s struma), autoimmune disease

E. Hypothyroidism

    a. if congenital can lead to cretinism

            1. early symptoms = persistent physiologic jaundice, hoarse cry, somnolence, feeding problems, constipation

    b. adult hypothyroidism (affects almost all systems)

        1. early c/o sluggishenss, wgt gain, sleepiness

        2. intolerance to cold

        3. constipation

        4. stiff aching muscles

        5. pernicious anemia (12% of the time)

        6. elevation of diastolic BP, decreased C.O., enlarged heart

        7. coarsening of skin, hair

        8. weight gain

    c. myxedema (severest form of adult hypothyroidism)

F. Hyperthyroidism

    a. Causes

        1. toxic diffuse goiter (Graves Disease)

        2. toxic multi nodular goiter

        3. thyroiditis

        4. meatastic thyroid cancer

        5. pituitary hyperthyroidism

    b. clinical picture (related to increased metabolic rate, increased cardiac         and respiratory stimulation and increased nervous system activity)

        1. nervousness

        2. increased sweating

        3. intolerance to heat

        4. palpitations, tachycardia

        5. fatique, weakness

        6. wgt loss with increased appetitie

        7. dyspnea

        8. diarrhea

        9 goiter

        10. thyroid bruit

        11. fine tremors

        12. glucose intolerance

        13. increased serum clacium

    c. Thyroid Storm (life threatening complication of hyperthyoidism)

    d. Grave’s disease

        1. characterized by triad of goiter, hyperthyroidism, exopthalmous

        2. autoimmune disease

3. role of Long Acting Thyroid Stimulator (LATS)

Adrenal

A. Review of anatomy and Physiology

    1. Diagram of Hypothamic- Pituitary- Adrenal Interaction

    2. Circadian rhythm of Glucocorticoid Secretions

B. Addison’s Disease (hypoadrenalism)

    a. Causes

    b. distinguish between primary and secondary

    c. symptoms have gradual onset- asthenia (cardinal complaint), anorexia, n&v, abd pain

    d. mineralcorticoid defeiciency

        1. decreased extracellular fluid (leads to hypotension), hyperkalemia, mild acidosis

    e. glucorticoid deficiency

        1. hypoglycemia (leads to sluggishness)

    f. melanin pigmentation

    g. Addisonian crisis - severe exacerbation of adrenal insufficiency, characterized by hypotension, shock, coma

C. Cushing’s syndrome (Hyperadrenalism)

    a. Causes

    b. special characteristic is mobilization of fat from lower body parts with  concomitant extra deposition of fat in thoracic and upper abdominal regions leading to "buffalo torso"

    c. 80% have hypertension, edema of face ("moon facies") (due to excess aldosterone)

    d. other symptoms = hirsutism, acne, oligomenorrea, aenorrhea ( excess androgens, estrogens)

    e. effects on carbohydrate and protein metabolism (due to excess  cortisol)

            hyperglycemia, DM, protein catabolism, loss of lymphoid tissue, diminished immune response, loss of collagen (characteristic purple striae), osteoporosis

D. Pheochromocytoma (catecholamine producing tumor of adrenal medulla)

    a. symptoms- paroxysmal hypertensive episodes, plapitations, severe headache, profuse diaphoresis, flushing, n&v, wgt loss, tremors

    b. diagnosis- increased vanilmandelic acid (VMA) in urine after 24 hour  urine