Endocrine Gross Lab

Question 1

If the parathyroid glands are grossly obvious, either:

Answer 1

1) they are big
2) the thyroid gland is small

Question 2

pathogenesis of renal secondary hyperparathyroidism.

Answer 2

Loss of nephrons ->
* ↓ renal 1-α-hydroxylase -> ↓ activation of 25OHD to calcitriol -> ↓ Ca -> ↑ PTH
* ↓ Ca retention & ↓ P excretion (therefore in blood = ↓ Ca & ↑ P) -> ↑ PTH
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PTH:
* ↑ release of Ca from bones -> ↑ Ca blood
* ↑ Ca reabsorption & ↑ P excretion -> ↑ Ca & ↓ P blood
* ↑ calcitriol -> ↑ Ca absorption from gut -> ↑ Ca blood
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However, if inadequate mass of renal cells to respond
* Ca:P imbalance cannot be corrected by PTH

Question 3

Well circumscribed nodule in the thyroid gland of a horse > cannot be parathyroid neoplasia/hyperplasia in this species because why?

Answer 3

Horses do not have internal parathyroid glands!
> separated from thyroid, so circumscribed growth cannot be parathyroid gland

Question 4

what are the differentials for a thyroid nodule. When they are productive, what do they produce?

Answer 4

• Follicular Cell: thyroglobulin
• C-Cell: calcitriol
• Nodular hyperplasia, adenoma
  > Common geriatric horse, incidental
• carcinoma
  > dogs

Question 5

Adrenal gland Cortex:Medulla:Cortex ratio
- what if it is off?

Answer 5

~1:1:1
It is easiest just to remember that the medulla shouldn’t be thicker than the cortex!
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We discussed that when the ratio is off, there are typically 2 main options:
1) If cortex looks thin = cortical atrophy vs. medullary hyperplasia
2) If cortex looks thick = cortical hyperplasia vs. medullary atrophy
- (no hypoplasia please)

Question 6

adrenal gland tumour can sometimes grow into what important structure?

Answer 6

caudal vena cava