Parathyroid: Science and Clinical Flashcards Preview

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Flashcards in Parathyroid: Science and Clinical Deck (50):
1

Main effect of parathyroid hormone

raise the blood calcium

2

What are the 3 main ways PTH raises blood calcium?

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

3

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

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

4

Where is cholecaliferol converted into calcidilol?

the liver

5

What is calcidilol?

25hydroxyVitamin D3

6

Where is 25hydroxyVitaminD3 activated?

the kidneys

7

What is 25hydroxyVitamin D3 converted into in the kidney?

1,25dihydroxyvitamin D3

8

What is 1,25dihydroxyvitamin D3 also known as?

calcitriol

9

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

PCT - proximal convoluted tubule

10

Calcitriol actis on the gut to...

increase calcium and phosphate absorption

11

Calcitriol acts on the bone to...

increase resorption of calcium and phosphate

12

Calcitriol acts on the parathyroid gland...

in a negative feedback manner - inhibiting further PTH release

13

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

DCT - distal convoluted tubule

14

PTH acts on the bone to...

activate the osteoblasts which subsequently activate the pre-osteoclasts

15

osteoclasts are a form of....

macrophage - they respond to macrophage colony stimulating factor

16

Action of calcitonin

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

17

Calcitonin is released from...

the parafollicular cells of the thyroid gland

18

the majority of cases of primary hyperparathyroidism are caused by...

a solitary adenoma

19

Symptoms which may be associated with primary hyperparathyroidism

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

20

What genetic condition is primary hyperparathyroidism associated with?

MEN 1

21

What are the 3 Ps associated with MEN 1?

Parathyroid hyperplasia, Pancreatic endocrine tumours, Pituitary tumour

22

The MEN1 gene is a...

tumour suppressor gene

23

Investigations for primary hyperparathyroidism

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

24

what should be avoided in primary hyperparathyroidism?

excess calcium and vitamin D intake, avoid thiazide diuretics

25

Surgery is always indicated with primary hyperparathyroidism - TRUE/FALSE

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

26

Indications for surgery to treat hyperparathyroidism

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

27

Drug that can be used in tertiary and carcinoma hyperparathyroidism

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

28

Results from secondary hyperparathyroidism

decreased calcium and appropriately raised PTH

29

Causes of secondary hyperparathyroidism

decreased Vit D intake and chronic renal failure

30

Results of tertiary hyperparathyroidism

raised Ca and very raised PTH

31

cause of tertiary hyperparathyroidism

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

32

What is malignant hyperparathyroidism?

the release of PTH-related protein from some cancers

33

Cancers associated with malignant hyperparathyroidism?

squamous cell lung cancer, breast and renal cell carcinomas

34

results in malignant hyperparathyroidism

decreased PTH and raised Ca

35

Brief causes of hypoparathyroidism

congenital absence, destruction, autoimmune, hypomagnesia, idiopathic

36

Symptoms of hypocalcaemia

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

37

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

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

38

Long term management of hypocalcaemia

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

39

Why is magnesium so important for calcium?

calcium release from cells is highly dependent on magnesium

40

Causes of hypomagnesia

alcohol, drugs, GI illness, pancreatitis, malabsorption

41

Drugs which may cause hypomagnesia

thiazides and PPIs

42

Pseudohypoparathyroidism is...

a genetic defect in the GNAS1 gene

43

Test results in pseudohypoparathyroidism

low Ca, high PTH - cells are PTH resistant

44

what is pseudopseudohypoparathryoidism?

all of pseudohypoparathyroidism but with normal calcium

45

Rickets and Osteomalacia are caused by...

vitamin D deficiency

46

potential causes of vitamin D deficiency

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

47

Clinical signs of vitamin D deficiency

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

48

Blood results with osteomalacia

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

49

malignancy associated with long term vitamin D deficiency

colon

50

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

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