06 - Hyperadrenocorticism

Question 1

(C. Hyperadrenocorticism - Cushing’s Syndrome and disease)

(CANINE)

(background - HPA axis)

1. Cushing’s syndrome involves chronic over-production of cortisol by what?
2. The clinical signs and sequelae are related to what?

(clinical signs)

a. Clinical signs: (1) Polyuria (PU) and compensatory polydipsia (PD), (2) polyphagia (PP; increased appetite and food intake), (3) abdominal distension (“pot-bellied”; secondary to muscle weakening/atrophy and hepatomegaly associated with deposits of glycogen/water and/or lipid), (4) muscular weakness, (5) alopecia/acne/calcinosis cutis, (6) increased panting, (7) testicular atrophy/anestrus, (8) myopathy (muscle wasting/catabolism)

b. Clinical laboratory findings:
CBC: mature neutrophilia, monocytosis, lymphopenia
Serum chemistry: elevated alkaline phosphatase (ALP), alanine aminotransferase (ALT), cholesterol, glucose, insulin, and lipids; decreased BUN.
Fasting serum cortisol–Although as a group, dogs with Cushing’s syndrome have significantly elevated serum cortisol levels, there is sufficient overlap with normal animals that this test is often of little practical value.
Other tests used include 24 hour urine cortisol levels, cortisol:creatinine ratios, ACTH stimulation test.

Answer 1

1. hyperactive cells of the adrenal cortex
2. the gluconeogenic, lipolytic, protein catabolic, and anit-inflammaotry effects of the glucocorticoid hormones on many organs

Question 2

(C. Hyperadrenocorticism - Cushing’s Syndrome and disease)

(CANINE)

(common etiologies)

1. What accounts for about 85% of spontaneous cases?

Associated mostly with what?

large macroadenomas may expand beyond the pitutiary and do what?

are malignant pituitary tumors common?

Answer 2

1. pitutiary dependent bilateral adrenal cortical hyperplasia/hypertrophy (diffusely widened adrenal cortex, esp. zona fasciculata)

functional (ACTH-secreting) microadenomas (<1cm in diameter) of pituittary gland (most from pars distalis, some from pars intermedia) or macroadenomas

damage adacent hypothalamus

no they are rare

Question 3

(C. Hyperadrenocorticism - Cushing’s Syndrome and disease)

(CANINE)

(common etiologies - cont)

1. what accounts for 10-15% of cases?

the non-neoplastic remnant adrenal cortical tissue in both the affected gland and in the contralateral gland are atrophied due to what?

2. also iatrogenic (often chronic administration of corticosteroids)

Answer 3

1. primary functional adrenocortical ademona/carcinoma

negative feedback inhibition of pituitary ACTH secretion by the increased blood cortisol concentration

Question 4

(C. Hyperadrenocorticism - Cushing’s Syndrome and disease)

(CANINE)

(Lesions in other body systems)

1. Liver steroid hepatopathy (hepatocellular vacuolar degeneration; glycogen and/or water) is a frequent finding in dogs exposed to what?

what does the liver look like?

microscopically?

Answer 4

1. high levels of corticosteroids

enlarged and pale

there are scattered clusters of extremely enlarged and vacuolated hepatocytes that are surrounded by normal or mildly vacuolated hepatocytes. Vacuoles are composed of glycogen and water; lipidosis is not a feature.

Question 5

(C. Hyperadrenocorticism - Cushing’s Syndrome and disease)

(CANINE)

(Lesions in other body systems)

(Skin)

b. Skin–The pattern of “endocrine dermatosis” (see under hypothyroidism) is a consistent feature of canine Cushing’s syndrome. Unique features of Cushing’s syndrome include calcification of dermal collagen (calcinosis cutis) and atrophy of sweat glands.

Question 6

(C. Hyperadrenocorticism - Cushing’s Syndrome and disease)

(EQUINE)

(background)

There is some disagreement as to whether the syndrome observed in horses with tumors of the pars intermedia (pituitary) is truly Cushing’s syndrome/disease (ie., signs attributable to hypercortisolism) or if they are principally due to tumor damage to the adjacent hypothalamus, or both. There is also autonomous production of excess pro-OMC-derived peptides. Cushing’s syndrome/disease in horses is distinctly different from the disease in dogs, cats, and humans.

Question 7

(C. Hyperadrenocorticism - Cushing’s Syndrome and disease)

(EQUINE)

(clinical features)

1. age?
2. ponies more commonly affected than horses
3. sex prediletion?
   b. Clinical signs: chronic laminitis and sole abscesses, polyuria/polydipsia (PU/PD), polyphagia (PP), muscle weakness/wasting, somnolence (drowsiness), intermittent hyperpyrexia, and generalized hyperhidrosis (abnormally increased sweating/perspiration). Hirsutism (irregular/excessive hair coat/hypertrichosis throughout the year) is a common manifestation and is due to failure of seasonal shedding.
   c. Clinical laboratory findings may include hyperglycemia and glucosuria (likely the result of down-regulation of insulin receptors on target cells induced by chronic excessive intake of food and hyperinsulinemia and increased cortisol and other hormones that are insulin antagonists). Plasma cortisol levels are normal to modestly elevated, do not show normal diurnal variation, and are not suppressed by dexamethasone.

Answer 7

1. 19 yrs (range 7-40)
2. NO

Question 8

(C. Hyperadrenocorticism - Cushing’s Syndrome and disease)

(EQUINE)

(etiology)

1. what is it?
2. these tumors contain what?

Answer 8

1. pituitary tumor of the pars intermedia
2. pro-opiomelanocortin (POMC) and several of its cleavage products such as beta-endorphin, beta-melanocyte stimulating hormone, and ACTH

Question 9

(Diabetes Mellitus)