parathyroid

Question 1

parathyroid pathology revolved around

Answer 1

calcium - hypercalaemia
may be a cause or effect of parathyroid disease
parathyroid disease is not the only cause of hypercalcaemia

Question 2

normal parathyroid is made up of

Answer 2

thin capsule with islands of parathyroid cells with fat in-between

Question 3

parathyroid glands are located

Answer 3

four of the at the periphery of the thyroid

Question 4

cell types in they parathyroid

Answer 4

chief cells 
with variants (oxyphil and water clear) due to accumulation of other material

Question 5

parathyroid hormone is produced by

Answer 5

chief cells

Question 6

parathyroid hormone is released in response to

Answer 6

low serum calcium - free ionised calcium.

Question 7

actions of parathyroid hormones

Answer 7

• bone resorption
• renal tubular resorption of calcium
• increases conversion of vit D to active (hydroxy) form in the kidney
• with vitamin D, promotes calcium resorption from small intestine
• increases urnary phosphate excretion causing phosphaturia
• net effect is to increase serum calcium

Question 8

net effect of PTH

Answer 8

increase serum calcium

Question 9

hypocalcaemia

Answer 9

usually due to accidental damage/removal of parathyroids during thyroid surgery

Question 10

hypocalcaemia is usually due to

Answer 10

chronic renal failure, vit D deficiency, drugs, or intestinal malabsorption of Ca

Question 11

hypocalcaemia causes

Answer 11

neuromuscular irritability

calcium. blocks sodium channels, so lower calcium decreases depolarisation threshold

Question 12

symptoms of hypocalcaemia

Answer 12

CATs go numb
- convulsons, arrythmas, tetany, numbness/paresthesia

acute - syncope, cardiac arrhythmia, laryngospasm

Question 13

hypercalcaemia is caused by

Answer 13

accelerated bone resorption
excessive GI absorption
Decreased renal excretion of calcium

Question 14

diseases causing hypercalcaemia

Answer 14

• hyperparathyroidism
• hypercalcaemia of malignancy
• drugs, metabolic/genetic disorders, chronic granulomatous disease

Question 15

how is hypercalcaemia caused from malignancy

Answer 15

• bone osteolysis due to skeletal metastasis
• metabolic effects of malignant tumours - cytokine mediated
• PTHrP secretion from tumours

Question 16

excessive parathyroid hormone

Answer 16

increased PTH from parathyroid or PTHrP (parathyroid related protein) causes bone resorption

Question 17

excessive parathyroid hormone may be caused by

Answer 17

hyperthyroidism due to parathyroid tumours

extolc secretion of pTHrP by some other tumours

Question 18

disrupted Ca/PO4 homeostasis

Answer 18

retention of phosphate inappropriately activates feedback loop leading to increased PTH secretion

Question 19

disrupted Ca/PO4 is caused by

Answer 19

renal failure

Question 20

excess vitamine D

Answer 20

excess vit D causes increases absorption (gut) respiration (kidney) and mobilisation (bone)

Question 21

excess vit D is caused by

Answer 21

vit D intoxication, sarcoidosis, idiopathic hypercalcaemia of infancy

Question 22

clinical manifestations of hypercalcaemia

Answer 22

stones, bones, abdominal groans and psychiatric moans

cardiovascular, ocular, dermatological

Question 23

primary hyperparathyroidism

Answer 23

excesss PTH production from the parathyroid
feedback indepedant production of PTH
one or more involved gland increasing in size while the others atrophy

Question 24

secondary hyperparathyroidism

Answer 24

other disease process drives increase in PTH production
abnormal homeostatic regulation but normal feedback mehcniasms
glands become hyper plastic

Question 25

tertiary hyperparathyroidism

Answer 25

autonomous PTH secretion, caused by long standing secondary HP abnormal feedback mechanisms usually due to long standing kidney disease often autonomous nodule within hyper plastic glands

Question 26

ectopic secretion

Answer 26

parathyroid hormone related protein paraneoplastic from other malignancies feedback independent causing atrophy

Question 27

malignancy of parathyroid

Answer 27

rare

Question 28

parathyroid adenoma

Answer 28

benign neoplasm of parathyroid epithelium most hyperparathyroid usually solitary, occasionally multiple

Question 29

multiple parathyroid adenoma may indicate

Answer 29

MEN1

Question 30

parathyroid adenoma histological patterns

Answer 30

``` sheets, acini, follicles, trabecular uniformity of cell type loss of reticulum;in framework no intraglandular fat rim of normal ```

Question 31

parathyroid hyperplasia

Answer 31

increased numbers of cells - polyclonal typically involves all glands but may be asymmetrical - usually <1g mainly chief cells, may have mixed cell type, a nodular pattern - usually sporadic, may be familial

Question 32

familial parathyroid hyperplasia

Answer 32

- MEN1 - most patients - homozygous loss of suppressor gene on chromosome 11 - less commonly MEN 2a