Endo 5 Hypersecretory States of Anterior Pituitary

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					Endo 5 Hypersecretory States of Anterior Pituitary
Anterior Pituitary Hormones: makes 6 hormones
    1. Thyroglobulin: TSH
    2. Corticotropin: ACTH
    3. Gonadotropins: FSH & LH
    4. Prolactin: PL
    5. Growth Hormone: GH
Posterior Pituitary Hormones: stored here, not made here
    1. Arginine vasopressin: AVP(ADH)
    2. Oxytocin
Effects of Pituitary Tumors: Adenomas
     Lead to hormone excesses or deficiencies
     Cause mechanical problems by impinging on neighboring structures
Hypopituitarism: Causes
     Isolated hormone deficiencies, Tumors, Inflammatory diseases, Vascular diseases, Destructive-
         traumatic events, Developmental abnormalities, Infiltration, Idiopathic
Hypopituitarism: Causes
     Tumors
              Hypothalamic or pituitary or Pituitary apoplexy
     Inflammatory diseases
              Granulomatous diseases: Sarcoid, TB, Syphilis, Granulomatous hypophysitis
              Eosinophilic granuloma
              Lymphocytic hypophysitis (autoimmune)
     Vascular diseases
              Sheehan’s postpartum necrosis
              Diabetic peripartum necrosis
              Carotid aneurysm
     Infiltration
              Hemochromatosis
              Amyloidosis
Pituitary Hormone Control
     Simple end organ feedback inhibitory loops
              ACTH excess-Cushing’s disease
                   TSH excess-Hyperthyroidism
                    FSH/LH excess-Hypogonadism
     Absent simple end organ feedback inhibitory loops
                    PL excess  Galactorrhea and Hypogonadism
                    GH excess  Acromegaly and Gigantism, only effects height if before plates close
Effects of Large Pituitary Tumors
     Hypopituitarism (partial or complete) by compression of the adjacent normal gland or the
         pituitary stalk
     Neurologic disturbances: Visual fields-optic chiasm compression, Other-invasion of cranial
        fossae or cavernous sinuses: CNIII/IV/V/VI, ICA, Headache
Hypothalamic Diseases may cause hypopituitarism with the exception that PL secretion increases
Prolactin: numbers not necessary
     Normally 10-25% of anterior pituitary
     Increases to 70% with pregnancy
     Normal serum conc 2-15 ng/ml
     Essential for lactation
     PIF/Dopamine effect
     Other stimulatory factors: Stress, Estrogens, Opiates, Diseases problems w/ PL secretion
Hyperprolactinemia
     Hypogonandism-due to inhibition of GnRH release from hypothalamus
              Women: Irreg menses, infertility, osteoporosis           Men: Impotence, infertility
     Galactorrhea-milk production in a nonpostpartum patient
              Women: 30-90%          Men: Rare
     D/dx: Autonomous production-pituitary adenoma, Decreased dopamine/dop inhibitory action-
        hypothalamic ds, Stimuli that overcome normal dopamine inhibition-estrogens, hypothyroidism,
        Decreased PL clearance-renal failure, Unknown causes-cirrhosis, primary AI, Pit/Hypothal/Pit
        stalk ds, drugs (esp pych drugs)
     Lab eval: Hypogonadism/galactorrhea/other, Serum prolactin: <30 – stress, >300 – pit
        adenoma, > 100 and not preg = usu adenoma, hCG – Pregnant?, TSH – Hypothyroid?, Hx -
        Postpartum? RF? Cirrhosis? Drugs?
              If unexplained, get CT/MRI with contrast
                             • Macro: easily visualized
                             • Micro: if <10 mm, may not see: Follow!
Prolactinomas
     Most common type of functional pituitary adenoma
     Size correlates well with hormonal output
     Micro more common than Macro
              Micro: 90%female/10%male             Macro: 60%male/40%female
     May grow during pregnancy- watch for enlargement/ check levels, can’t live w/o TSH and ACTH
     Tx: Micro: treat if symptomatic: Bromocriptine (dopamine agonist)
              Macro: most require treatment: Bromocriptine, Tamoxifen, Transsphenoidal resection,
                 Radiation tx
Growth Hormone/Somatotropin
     Normal 50% of ant pit
     Normal serum conc varies: pulsitile release
     Fxns: Essential for normal linear growth, Acts indirectly through somatomedians or insulin-like
        growth factors, Trophic factor for insulin release, Anabolic hormone, Other
     Control: hypothal regulation: GRH, SRIF/Somatostatin
Growth Hormone Excess
     Gigantism: before epiphyseal closure in peds
    Acromegaly: insidious, chronic, debilitating ds assoc with boney and soft tissue overgrowth;
       uncommon; middle age; increased mortality rate (male: CV, resp; female: CVA, resp)
    Diagnosis: Usu 7-8 yrs before dx, Increased GH not sufficient for dx
            Must do GH inhibition test with standard glucose load, Should screen all pts with large
              pit adenomas for GH excess (CT/MRI), Check ant pit fxn for other hormones
    Treatment : Goals: Decrease GH levels to normal, Decrease tumor size, Preserve normal pit fxn
            Methods: Surgery: Transsphenoidal, Radiation: Heavy particle, conventional, Meds:
              Bromocriptine-adjunct to tx
    Labs: Hyperglycemia, Hypercalcuria, Hypercalcemia, Hyperphosphatemia, Hyperprolactinemia
    Pathophysiology: Adenomas: 75% macro at time of dx, Usually primary pit problem, Rare GRH
       induced, Rare ectopic
Growth Hormone Deficiency
    Often GH is first hormone to be lost with pit/hypothal probs
    Often dx only with stimulation tests for GH release
    Adults: if have DM, may see decreased insulin requirements, hypoglycemia
    Children: impaired growth, short stature

				
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posted:9/18/2012
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