Acromegaly Flashcards Preview

Endocrinology > Acromegaly > Flashcards

Flashcards in Acromegaly Deck (16):
1

Acromegaly

  • Excess GH
  • Overgrowth of bone and soft tissue

2

GH secretion

  • Controlled by negative feedback inhibition to Hypothalamus
  • GH negatively feeds back on Pituitary and Hypothalamus
  • Hypothalamus releases GHRH, stimulates Pituitary to release GH, goes to the liver and stimulates release of IGF 4
    • IGF 4 causes tissue growth

3

Main Causes acromegaly

  • Dogs: Progestins mainly
    • exogenous
    • Endogenous - females
    • Pituitary tumor (VERY RARE)
    • Hypothyroidism in dog can inc endogenous GH release
      • by decreasing pituitary somatostatin
  • Cats: pituitary tumor only

4

aside about hypothyroidism....

  • Can make a dog make acromegalic
    • hypothyroidism can inc GH release by decreasing pituitary release of somatostatin
    • Boxer gone Mastif!

5

Insulin resistence

  • Insuline resistance at postreceptor sites
    • predisposes to Diabetes Mellitus
  • All the cats will be diabetic

6

Pathophys of GH secretion

  • peripheral insuline resistance => hyperglycemia (DM)
  • Inc in somatomedin C (IGF 1) => proliferation bone, cartilage, soft tissues

7

GH can be _____

  • Oncogenic

8

Physical changes acromegaly

  • gingival hyperplasia
  • inc skin folds
  • laryngeal hyperplasia and stridor
  • enlarged maxilla, widening of teeth space
  • protruding jaw

9

Radiographic changes acromegaly

  • inc oropharyngeal soft tissue
  • Broadened metaphalanges
  • windened interdental spaces
  • inc head and limb soft tissue
  • calvarium hyperostosis

10

Clinical pathology acromegaly

  • anemia or polycythemia
  • mild hyperphosphatemia
  • elevated alkaline phosphatase
  • Elevated ALT
  • +/- Hyperglycemia
    • most acromegalic cats are diabetic
    • some dogs are diabetic
  • +/- glycosuria if diabetic

11

Acromegaly DX

  • Clinical features and PE
  • IGF-1
  • We don't measure GH, but Europe does

12

DM acromegaly cats are rarely

  • ketoacidotic
    • enough insulin gets to liver to deter ketogenesis

13

Feline Acromegaly signs

  • PD/PU/Polyphagia => earliest sign
  • Organ enlargement
    • liver, heart, tongue, kidneys
  • Cardiomyopathy
  • Lameness
  • CNS dysfunction => Late sign from pituitary tum

14

assoc pathology of acromegaly

  • Pituitary tumor
  • Myocardial wall hypertrophy
  • Arthropathy 
  • Glomerulopathy

15

Acromegaly Tx

  • Iatrogenic => D/C progesterone TX
  • Natural onset female dog => OHE
  • Pituitary tumor => surgery/radiation
  • no medical therapy
  • give insulin as needed, if diabetic

16

Acromegaly prognosis

  • Dog => good
  • Cat => poor