Pituitary Gland Endocrinopathies Flashcards
What endocrinopathies may be connected to the pituitary gland. What hormones from the hypophysis affect the pituitary.
A) Anterior lobe - ACHT, GH, PRL, TSH, LH, FSH Posterior lobe - alphaMSH, AVP, oxytocin B) GHRH, TRH, LHRH, CRH...
Name the endocrinopathies in connection with the growth hormone
- congenical hyposomatotropism (GH deficiancy)
- alopecia-X (GH responsive dermatosis, lacking GH in 2/3)
- acromegaly (GH excess in mature animals)
Congenital Hyposomatotropism - signalment and pathogenesis
- German shepherds and Carelian bear dogs
- Autosomal recessive inheritance
- GH AND cyst formation in pit -> other hormones affected too, TSH decr - Secundary hypothyroidism, decr T4)
Congenital Hyposomatotropism Clinical signs
~ Poor growth of puppies (3-5. months)
~ Normal body proportions (!!)
~ Retention of lanugo/puppy fur (missing guard hairs/part of coat)
~ Later: alopecia (lanugo gone), hyperpigmentation, thin skin
~ Fox-like face (shorter mandible) brachygnathia inferior
~ (megaoesophagus, cryptorchidism)
~ From 2-3 years of age: Poor differentiation of tissues - deficient kidney deveopment
activity⬇️, appetite⬇️, renal failure –> euthinasia!
Congenital Hyposomatotropism - Diagnosis
(Main indication is lack of GH and less elastic fibers)
🔺 Skin biopsy: elastic fibres ⬇️
🔺 Xylazine-, clonidine-, GHRH-stimulation tests
➡️ GH-measurement (frozen sample! Unstable hormone, not really used!)
🔺 Insulin-like growth factor (IGF-I)
– Bound to carrier proteins ➡️longer plasma half-life (a substance produced in proportion to GH - we can measure this instead! But ref range differ btw breeds, we have for german shepard.)
🔺 (TSH- / TRH-stimulation tests)
Congenital Hyposomatotropism - Treatment
🔺 Bovine- / porcine- / human-GH
– 0,1-0,3 IU/kg three times weekly SC
– Antibody development ➡️ no permanent cure
(There is no Ca version so the immune system will recognize the GH as alien at some point)
🔺 T4-therapy
Congenital Hyposomatotropism - prognosis
3-5 years old: euthanasia requested due to kidney problems, anorexia
Describe the background of alopecia-X
= GH responsive dermatosis?
~ Many unresolved questions
Usually due to GH deficiancy. Sometimes no decr in GH - subclinical cushings with abn picture disease might be.
- GH low in 2/3
- IGF-I usually normal!
- incr. androgen production of adrenals - mild Cushing’s syndrome is the cause?
What are the signs of alopecia-X
Very typical!! Lion-like
Symmetrical alopecia, hyperpigmentation(dark) on the neck, trunk, caudal surfaces of thighs
How do you treat alopecia-X
~ GH-replacement? (If certain deficiancy is present, if not can trigger DM! GH is diabetogenic)
~ Some cases recover without any treatment
~ Other dogs respond to castration or testosterone therapy
~ Trilostane, (mitotane) - reduce activity of adrenal cortex - sometimes favorable results
~ Melatonin (Pomeranian with alopecia-x melatonin wokrs! Makes further questions about the pathogenesis, pineal gland issue aswelll?
No SE - worth a try in dogs)
Describe the background of acromegaly
🔺 GH excess in mature animals, aka hypersomatotropism
🔺 Middle-aged bitches (⬆️ P4 > ⬆️ GH: ectopic prod. In mammary gland!!)
- Exogenous progestagens
- Mammary tumor
- Metestrus + Ovarian cyst: ⬆️P4
🔺 Middle-aged and old male cats
–Pituitary tumors (GH prod)
Signs of acromegaly
~ Body dimensions change:
big head, large paws, loose skin abdominal size⬆️(hepato- & renomegaly)
~ Protruding tongue, prognathia inferior, interdental spaces wider
~ Snoring, insp dyspnea (soft palate growth)
~ PD/PU (GH excess is connected to insulin resistence dm!)
~ Glycosuria (diabetes mellitus)
~ Cats: insulin-resistant diabetes mellitus (above signs are usually mild)
➡️ Acromegaly, dm, igf-1 high = GH excess - investigation of soure of insulin resistance needed!
Acromegaly treatment
🔺 Discontinuation of progestagens + aglepristone (Alizin inj. A.U.V.) or total mammectomy?
🔺 Ovariectomy, excision of mammary tumor
🔺 (Temporary) insulin therapy (much higher dose needed!)
🔺 Cats: (always pit tumor overprod GH!)
– Hypophysectomy (only microadenomas(?))
– Cobalt irradiation (conservative - shrink tumor)
– Somatostatin? (frequent administration, expensive) – Insulin therapy
Prognosis of acromegaly
Usually good in dogs, guarded to poor in cats
Diabetes insipidus - what is it?
Antidiuretic hormone (ADH) = arginine-vasopressin (AVP)
➡️ produced and stored in pituitary gland
~ action of ADH decrease causing diabetes insipidus (DI)
