Parathyroid: Science and Clinical

Question 1

Main effect of parathyroid hormone

Answer 1

raise the blood calcium

Question 2

What are the 3 main ways PTH raises blood calcium?

Answer 2

1. breaking down bone 2. increasing absorption of calcium from food 3. increasing the kidneys ability to hold onto calcium

Question 3

7-dehydrocholesterol is converted by UV waves into ____________ or cholecalciferol

Answer 3

7-dehydrocholesterol is converted by UV waves into VITAMIN D3 or cholecalciferol

Question 4

Where is cholecaliferol converted into calcidilol?

Answer 4

the liver

Question 5

What is calcidilol?

Answer 5

25hydroxyVitamin D3

Question 6

Where is 25hydroxyVitaminD3 activated?

Answer 6

the kidneys

Question 7

What is 25hydroxyVitamin D3 converted into in the kidney?

Answer 7

1,25dihydroxyvitamin D3

Question 8

What is 1,25dihydroxyvitamin D3 also known as?

Answer 8

calcitriol

Question 9

Calcitriol acts on the ____ of the kidney to increase calcium absorption

Answer 9

PCT - proximal convoluted tubule

Question 10

Calcitriol actis on the gut to…

Answer 10

increase calcium and phosphate absorption

Question 11

Calcitriol acts on the bone to…

Answer 11

increase resorption of calcium and phosphate

Question 12

Calcitriol acts on the parathyroid gland…

Answer 12

in a negative feedback manner - inhibiting further PTH release

Question 13

PTH acts on the ____ of the kidney to increase calcium reabsorption

Answer 13

DCT - distal convoluted tubule

Question 14

PTH acts on the bone to…

Answer 14

activate the osteoblasts which subsequently activate the pre-osteoclasts

Question 15

osteoclasts are a form of….

Answer 15

macrophage - they respond to macrophage colony stimulating factor

Question 16

Action of calcitonin

Answer 16

released in response to raised plasma calcium and has opposite effects to PTH

Question 17

Calcitonin is released from…

Answer 17

the parafollicular cells of the thyroid gland

Question 18

the majority of cases of primary hyperparathyroidism are caused by…

Answer 18

a solitary adenoma

Question 19

Symptoms which may be associated with primary hyperparathyroidism

Answer 19

weak, tired, thirsty, dehydrated, polyuria, renal stones, abdominal pain, pancreatitis, duodenal (less gastric) ulcers, fractures, osteoporosis or osteopaenia, increase BP

Question 20

What genetic condition is primary hyperparathyroidism associated with?

Answer 20

MEN 1

Question 21

What are the 3 Ps associated with MEN 1?

Answer 21

Parathyroid hyperplasia, Pancreatic endocrine tumours, Pituitary tumour

Question 22

The MEN1 gene is a…

Answer 22

tumour suppressor gene

Question 23

Investigations for primary hyperparathyroidism

Answer 23

raised Ca, raised or normal PTH, decreased phosphate, increased Alk Phos, 24 hr urinary Ca, DEXA, X-ray, CT

Question 24

what should be avoided in primary hyperparathyroidism?

Answer 24

excess calcium and vitamin D intake, avoid thiazide diuretics

Question 25

Surgery is always indicated with primary hyperparathyroidism - TRUE/FALSE

Answer 25

FALSE - surgery is only indicated if there is end-organ damage

Question 26

Indications for surgery to treat hyperparathyroidism

Answer 26

bone disease, gastric ulcers, renal stones, osteoporosis, less than 50 years old, renal impairement (<60ml/min eGFR)

Question 27

Drug that can be used in tertiary and carcinoma hyperparathyroidism

Answer 27

cinacalet - increases the PT to increased calcium thus reducing the production of PTH

Question 28

Results from secondary hyperparathyroidism

Answer 28

decreased calcium and appropriately raised PTH

Question 29

Causes of secondary hyperparathyroidism

Answer 29

decreased Vit D intake and chronic renal failure

Question 30

Results of tertiary hyperparathyroidism

Answer 30

raised Ca and very raised PTH

Question 31

cause of tertiary hyperparathyroidism

Answer 31

prolonged secondary hyperparathryoidsim causes glands to start acting autonomously - chronic renal failure

Question 32

What is malignant hyperparathyroidism?

Answer 32

the release of PTH-related protein from some cancers

Question 33

Cancers associated with malignant hyperparathyroidism?

Answer 33

squamous cell lung cancer, breast and renal cell carcinomas

Question 34

results in malignant hyperparathyroidism

Answer 34

decreased PTH and raised Ca

Question 35

Brief causes of hypoparathyroidism

Answer 35

congenital absence, destruction, autoimmune, hypomagnesia, idiopathic

Question 36

Symptoms of hypocalcaemia

Answer 36

paraesthesia, muscle cramps, weakness, tetany, fatigue, bronchospasm, fits, Chovsteks sign, Trousseau sign, QT prolongation

Question 37

Acute hypocalcaemia is an emergency which is treated with...

Answer 37

IV calcium gluconate, 10ml, 10% over 10 mins in 50ml dextrose

Question 38

Long term management of hypocalcaemia

Answer 38

calcium supplement of 1-2g a day, Vit D tabs or depot injection

Question 39

Why is magnesium so important for calcium?

Answer 39

calcium release from cells is highly dependent on magnesium

Question 40

Causes of hypomagnesia

Answer 40

alcohol, drugs, GI illness, pancreatitis, malabsorption

Question 41

Drugs which may cause hypomagnesia

Answer 41

thiazides and PPIs

Question 42

Pseudohypoparathyroidism is...

Answer 42

a genetic defect in the GNAS1 gene

Question 43

Test results in pseudohypoparathyroidism

Answer 43

low Ca, high PTH - cells are PTH resistant

Question 44

what is pseudopseudohypoparathryoidism?

Answer 44

all of pseudohypoparathyroidism but with normal calcium

Question 45

Rickets and Osteomalacia are caused by...

Answer 45

vitamin D deficiency

Question 46

potential causes of vitamin D deficiency

Answer 46

gastric surgery, coeliac disease, liver disease, pancreatic failure, chronic renal failure, lack of sunlight, drugs i.e. anti-convulsants

Question 47

Clinical signs of vitamin D deficiency

Answer 47

low calcium, muscle wasting (proximally), dental defects (caries and enamel), bone tenderness with deformity, fractures or pseudofractures

Question 48

Blood results with osteomalacia

Answer 48

low Ca, low PO4, high Alk Phos, low Vit D, high PTH

Question 49

malignancy associated with long term vitamin D deficiency

Answer 49

colon

Question 50

Vitamin D3 tablets come in 2 forms which are...

Answer 50

calcitriol (1,25 Vit D3), alfacalcidilol (1a Vit D3)