Endocrine Pathology

  1. What are the three types of intercellular signalling?
    Autocrine, paracrine and endocrine signalling
  2. What is an endocrine gland?
    A group of specialised epithelial cells that synthesise, store and release their secretions directly into the bloodstream for them to have physiological effects on distant target cells
  3. What are the 5 mechanisms of endocrine disease?
    • 1. Hypofunction
    • 2. Hyperfunction
    • 3. Endocrine dysfunction due to neoplasia
    • 4. Failure of target cell response
    • 5. Abnormal hormone degredation
  4. What type of clinical signs can commonly be seen in the following body systems due to endocrine disease? a) skin b) nervous system c) urinary system d) skeletal system
    • a) alopecia, hirsutism
    • b) seizures 
    • c) PU, PD
    • d) fractures
  5. List some of the main endocrine organs
    Pituitary, parathyroid, adrenal, thyroid, gonads, pancreatic islets,
  6. Which hormones are secreted from the a) anterior pituitary b) posterior pituitary?
    • a) GH, ACTH, TSH, FSH, LS, MSH, PRL
    • b) ADH and oxytocin
  7. Give possible causes of a) primary b) secondary anterior pituitary hypo function?
    • a) Aplasia/hyperplasia or destruction secondary to a space occupying lesion e.g. cyclic Rathke's pouch
    • b) hypothalamic malfunction
  8. What is a clinical condition caused by pituitary hypo function?
    Pituitary dwarfism
  9. What are the clinical signs of pituitary dwarfism?
    • Decreased growth rate
    • Abnormal hair coat - retention of puppy coat > alopecia, bilaterally symmetrical alopecia, hyper pigmentation
    • Hypoplasia of gonads and genitalia 
    • Delayed permanent dentition and epiphyseal closure
  10. Give an example of a breed that suffers from congenital cysts of Rathke's pouch leading to pituitary dwarfism?
    GSD, Spitz, Toy pinscher, carellian bear dogs
  11. What is the clinical syndrome of posterior pituitary hypo function?
    Diabetes insipidus (watery urine)
  12. Give examples of causes of a) primary b) secondary posterior pituitary hypo function?
    • a) destruction of the neurohypophysis or central diabetes insipid us
    • b) nephrogenic diabetes insipidus - renal tubules no longer respond to ADH
  13. How does posterior pituitary hypo function result in diabetes insipidus?
    • Primary - defect in hypothalamus, lack of secretion of ADH, diabetes insipidus i.e. PU, PD, low urine specific gravity
    • Secondary - renal tubules insensitive to ADH, adequate ADH,  diabetes insipidus i.e. PU, PD, low urine specific gravity
  14. Give possible causes of pituitary hyperfunction
    Functional neoplasms within the pituitary (adenoma, adenocarcinoma).  Can also be due to pituitary hyperplasia.
  15. What clinical condition can pituitary hyper function cause in dogs?
    Cushing's syndrome
  16. What are the clinical signs of Cushing's syndrome?
    • Bilaterally symmetrical non-pruritic alopecia
    • Comedones with dystrophic calcification
    • Flaccid abdominal wall due to muscle wasting
  17. What clinical condition can pituitary hyperplasia cause in horses?
    Equine pituitary pars intermedia dysfunction (Equine PPID)
  18. List some clinical signs seen with equine PPID
    • Polyphagia, polyuria, polydipsia
    • Hyperglycaemia
    • Laminitis
    • Generalised sweating
    • Somnolence
    • Striking hypertrichosis
  19. What clinical condition should you be careful not to confuse equine PPID with?  How would you tell them apart?
    • Equine metabolic syndrome
    • EMS occurs at a younger age than equine PPID. A positive diagnostic test for PPID is increased plasma ACTH without pain or stress.
  20. Give some examples of causes of hypoadrenocorticism?
    • Idiopathic
    • Damage - infectious, vascular, drug induced, etc
    • Secondary to pituitary hypofunction
  21. What is the clinical syndrome of hypoadrenocorticism?
    Addison's disease
  22. When might horses experience sudden severe adrenocortical hypo function?
    When there is massive, diffuse, often bilateral haemorrhage in overwhelming sepsis
  23. What is the most common cause of adrenal cortical hyper function or hyperadrenocorticism?
    Functional neoplasms within the adrenal cortex
  24. What clinical syndrome is caused by hyperadrenocorticism?
    Cushing's syndrome
  25. If the adrenal cortex is hyper functional concentrations of what hormones are likely to be affected?
    Cortisol, aldosterone and sex steroids
  26. Which hormones is likely to have the most immediate and profound effects clinically?
  27. What are the three forms of Cushing's Syndrome?
    • Pituitary dependent 
    • Adrenal dependent
    • Iatrogenic
  28. Describe what happens in pituitary dependent Cushing's syndrome
    The pituitary produces excessive ACTH eg pituitary tumour.  This stimulates the adrenal glands to produce more cortisol and results in bilateral adrenal enlargement.
  29. Describe what happens in adrenal dependent Cushing's syndrome
    The adrenal tumour produces increased cortisol which has negative feedback on the pituitary gland so less ACTH is produced by the pituitary
  30. How common is pituitary dependent vs adrenal dependent Cushings syndrome?
    85% vs 15% of cases
  31. What can cause iatrogenic Cushing's syndrome?
    Administration of exogenous steroids which act in lieu of the adrenal cortex
  32. True or false: adrenal medulla hypo function is common?
    False - it is rare
  33. What is the cause of adrenal medulla hyper function?
    Funcional neoplasia - phaeochromocytoma
  34. If the adrenal medulla is hyper functional concentrations of which hormones are likely to be affected?
    Catecholamines, adrenaline and noradrenaline
  35. Describe normal thyroid function
    The hypothalamus releases TRH which stimulates the pituitary to release TSH which acts on the thyroid gland and causes production of T4 and T3
  36. Is hypothyroidism common in cats or dogs?
  37. What are the possible a) primary b) secondary causes of hypothyroidism?
    • a) idiopathic follicular atrophy, lymphocytic thyroiditis (immune mediated)
    • b) decreased TSH from pituitary disease, Goitre
  38. What are the clinical signs of hypothyroidism?
    Lethargy, weight gain, exercise intolerance, hair thinning, poor quality coat, hyper pigmentation, pyoderma
  39. What is Goitre?
    A special type of thyroid dysfunction that results in inadequate T3/T4 synthesis and bilateral enlargement of the thyroid glands
  40. What causes Goitre?
    Iodine deficiency, iodine toxicity or goitrogenic plants
  41. Why is there bilateral enlargement of the thyroid glands during goitre?
    TSH production leads to thyroid enlargement but as there is no available iodine there is decreased T4 and T3 production.  This feeds back to the pituitary and leads to increased TSH production, and the cycle continues.
  42. What family of plants is goitrogen found in?
    Brassica eg kale, rape
  43. Give an example of when excess iodine is fed in the diet
    Seaweed fed to mares
  44. Is hyperthyroidism common in cats or dogs?
  45. What is the most common cause of hyperthyroidism?
    Functional neoplasms
  46. Parathyroid hypo function is rare but when might this occur?
    When the thyroid is surgically removed
  47. What are the three causes of secondary hyperparathyroidism?
    • Renal - decreased GFR, increased phosphate retention and relative hypocalcaemia, continued stimulation of the parathyroid gland
    • Nutritional - diet high in phosphate/low in calcium/low in vitamin D
    • Psuedohyperparathyroidism - tumours of non endocrine origin secreted PTHrP
  48. What can cause primary hyperparathyroidism?
    Functional neoplasm
  49. What are the four causes of pancreatic islet hypo function?
    Vacuolar degeneration, amyloidosis, immune mediated destruction, secondary to pancreatitis
  50. What clinical syndrome is caused by pancreatic islet hypo function?
    Diabetes mellitus
  51. What causes pancreatic islet hyper function?
    • Tumours
    • Non functional neoplasms and hyperplasia less common
  52. What type of tumour is more common: a cell or b cell pancreatic tumours?  And what hormone do they secrete?
    B cell - insulin
Card Set
Endocrine Pathology
Vet Med - Module 12