Endocrinology SA

Question 1

Addisons

Answer 1

Pituitary - lose ACTH
Immune mediated adrenal destruction (glomerulosa)

Question 2

Hyperthyroidism

Answer 2

Common for cats over 12
Aet - adenomatous hyperplasia of both lobes
Underlying cause not well defined

Question 3

Hyperthyroidism cats CS, Dx

Answer 3

CS -
Progressive
Weight loss
Hyperactive
PU/PD, tachycardia
Dx -
Palpation
Erythro and macrocytosis
More heinz bodies
Increased ALP, ALT, AST, LDH
Total T4 >90% of cases and to monitor
Free T4 (early cases, less sensitive)
T3 suppression test
Scintigraphy

Question 4

Hyperthyroidism Tx

Answer 4

Thiamazole - Inh. thyroid hormone synthesis
- check total T4 every 3 months
Carbimazole - Prodrug
Meds - reversible, don’t stop hyperplasia, pre op euthyroidism
Rapid recurrence if not compliant
Sx - uni/ bilateral thyroidectomy
Radioiodine- [] in thyroid hormone cells (best choice normally

Question 5

SHIM RAD

Answer 5

Severe hyperthyroidism
Huge thyroid tumour size
Intrathoracic Tumour
Multifocal Dz
Resistant to Antithyroid Drug

Question 6

CKD + Hyperthyroidism

Answer 6

Norm creatinine due to msc loss
Glomerular hyperfiltration
Tx can mask CKD
Thyroid storm - acute thyrotoxicosis
homeostasis overwhelmed with excess thyroid hormone

Question 7

Dogs hyperthyroidism

Answer 7

Functional tumour
Most common cause -
Iatrogenic 2° to oversupplementation (raw food)

Question 8

Thyroid hormone

Answer 8

Thyroid produces all T4, 40% T3
T3 and T4 plasma bound (99%)
Unbound thyroid hormone is active
T3 is more potent c.f. T4

Question 9

Hypothyroidism dogs

Answer 9

T3 and 4 deficiency
Mid-old age
Congenital - thyroid hypoplasia/ aplasia
1°-lymphocytic thyroiditis, idio atrophy
2°-pituitary/ hypothalamus defect, neoplasia/ iatrogenic

Question 10

Hypothyroidism Dx

Answer 10

Bio+Haemology-
Mild anaemia, hypercholoesterol, Mild up CK,
-increased ALP and ALT
Hrm-
Total/ free T4
Antibody measurement
Dynamic function tests (TSH stim)

Question 11

Hypothyroidism Tx

Answer 11

Levothyroxine - not with food or v. low bioavailability
CS clear-
Metabolic - weeks
Derm - months

Question 12

Endocrinopathies

Answer 12

Pituitary dwarfism
Acromegaly
Diabetes insipidus
Hyper/hypo PTH
Insulinoma (Panc)
Gastrinoma (Panc)
Phaeochromocytoma (adrenal)
Hyperaldosteronism (adrenal)

Question 13

PU/PD Ddx

Answer 13

DI - central, primary, secondary
Osmotic diureses- DM, 1°renal glycosuria, Fanconi’s syndrome, Post-Obst diuresis
Iatrogenic- glucocorticoids, diuretics, levothyroxine, phenobarbitone
Renal medullary wash out- loss of medullary hypertonicity
1° PD - Psychogenic
Def- PD >100ml/kg/day

Question 14

PU/PD work up

Answer 14

History (rule out iatrogenic)
Physical examination (evidence of renal dz, pyometra…)
Haematology (evidence of pyometra / pyelonephritis?)
Biochemistry (hyperCa? hypoNa? renal disease? diabetes?)
Bile acids (liver disease?)
T4 (hyperthyroidism?)
Urinalysis (diabetes, Faconi’s, renal glucosuria?. Culture to rule out pyelonephritis)
If none of above-
Hypercortisolism, Central DI, Primary NDI, 1° polydipsia
Rule out HAC then do water deprivation test

Question 15

Pituitary gland hormones

Answer 15

FSH
LH
ACTH
TSH
prolactin
Endorphoins
GH

Question 16

Pituitary dwarfism

Answer 16

GSD congenital lesion
Failure GH secretion
Proportionate dwarfism
-puppy coat, delayed dentition and growth plate closure
-immature gonads
Dx - routine testing, rule out other causes, IGF-1
Tx- progestagens- induce mammary GH secretion
-Adv effects
Don’t breed from

Question 17

Acromegaly

Answer 17

Excess GH
Cat- Old male pituitary tumour
Dog- FE, Mammary tissue response to progesterone

Question 18

Acromegaly pathogenesis

Answer 18

Chronic excess GH
Insulin antagonism-> DM
Anabolic effects (IGF-1)-> Organs, Cartilage, Bone

Question 19

Acromegaly Clinically, Dx, Tx

Answer 19

Clinical features-
Insulin resistant DM, Prognathism
Excess extremity growth
Dx-
Raised liver Ez, DM, Elevated IGF-1
Tx-
Bitch- OVH/ stop progestagens (bone change irreversible)
Cat- Control DM, hypophysectomy, Radiation of mass

Question 20

Central DI

Answer 20

Complete or partial deficiency in ADH (arginine vasopressin)
So collecting ducts are impermeable to water
Cause- neo/ trauma/ hypophysectomy sequelae

Question 21

1°Hyper PTH

Answer 21

Functional parathyroid tumour
So Hyper CA, PU/PD, dystrophic calcification
Dx- High total Ca, high PTH, mass detected
Tx- restore norm Ca levels, Sx mass removal

Question 22

2° Hyper PTH

Answer 22

Renal 2° Hyper PTH
Nutritional 2° Hyper PTH

Question 23

Pseudohyper PTH

Answer 23

PTH-rp secreting tumour
-Anal sac adenocarcinama
-lymphoma
-multiple myeloma

Question 24

Hypo PTH

Answer 24

Failure to produce PTH
1° - immune mediated
2° - Sx
CS- HypoCa signs
-Anxiety, muscle twitch, ataxia, tachycardia, weakness
Dx - low Ca, high PO4, low PTH
Tx-
Emergency- IVFT, IV Ca gluconate (slow, ECG)
Maintenance - Oral Ca and Vit D

Question 25

Insulinoma

Answer 25

Functional Beta cell tumour
So hypoglycaemia
CS- episodic, fasting, excitement, neuro, weight gain
Dx- persistent hypoglycaemia, elevated insulin
Tx- IV glucose, Prednisolone, Sx

Question 26

Gastrinoma

Answer 26

Functional pancreatic gatrin tumour
Gastric hyper acidity and ulceration risk
Sever GI signs
Dx- elevated gastrin, imaging, scoping
Tx- Sx (often metastasis)

Question 27

Phaeochromocytoma

Answer 27

Catecholamine adrenal medullary functional tumour
Episodic signs
-anxiety, tachycardia+pnoea, V&D, HYper BP (retinal detachment)
Dx- US, plasma metanephrines
Tx- radical excision (risky), BY meds
Often metastasise

Question 28

Hyperaldosteronism

Answer 28

Not in dogs
CS- PU/PD, weakness, neck ventroflexion (hypokalaemia)
- hypertension (Na retention)
Tx- restrict Na, supplement K
- Sx excision
- spironolactone (aldosterone antagonist)