Calcium and Bone Tutorial

Question 1

what 2 substances make up most of bone?

Answer 1

calcium phosphate

collagen

Question 2

which is the more dense of trabeclar and cortical bone?

Answer 2

cortical

Question 3

what is the general weight of total body calcium?

Answer 3

1.5kg

Question 4

what are the 3 main compartments of body calcium?

Answer 4

extracellular
intracellular
skeleton

Question 5

what compartment contains plasma calcium?

Answer 5

extracellular

Question 6

what secretes calcitonin?

Answer 6

parafollicular C cells in the thyroid gland

Question 7

where are the enzymes located that activate Vitamin D?

Answer 7

liver

kidneys

Question 8

what level of calcium in the body would trigger PTH?

Answer 8

(low) hypocalcaemia

Question 9

main functions of PTH?

Answer 9

increase serum Ca
decrease serum phosphate
activate vitamin D in kidney

Question 10

what kind of bone cell does PTH activate to cause resorption of bone and Ca?

Answer 10

osteoclast

Question 11

what does PTH do to the kidneys to increase Ca and decrease phosphate?

Answer 11

makes them undergo tubular resorption

Question 12

where is vitamin D synthesised?

Answer 12

intestine

Question 13

main role of vitamin D?

Answer 13

increases kidney absorption

Question 14

what 2 components make up vitamin D?

Answer 14

dehydrocholesterol from UV light

diet

Question 15

when is the only time that calcitonin is secreted?

Answer 15

only in extreme hypercalcaemia

Question 16

what is the main action of calcitonin?

Answer 16

decrease serum Ca

Question 17

how does calcitonin decrease serum Ca?

Answer 17

inhibits osteoclasts to decrease bone resorption AND decreases tubular resorption

Question 18

which substance has an opposing role to PTH?

Answer 18

calcitonin

Question 19

what areas of the body are stimulated in hypercalcaemia?

Answer 19

smooth muscle
heart
nerves
ALL INCREASE

Question 20

why do patients with hypercalcaemia get kidney stones?

Answer 20

increased levels of Ca in blood form stones with a high Ca content

Question 21

why do you get arrhythmias in hypercalcaemia?

Answer 21

increased excitability of the heart due to increased serum Ca

Question 22

why do patients get muscle weakness in hypercalcaemia?

Answer 22

although pts get stimulated smooth muscle, skeletal muscle is understimulated so they become weak

Question 23

what GI complaint is common of hypercalcaemia patients?

Answer 23

constipation

Question 24

what type of muscle is stimulated in hypocalcaemia? what are the symptoms of this

Answer 24

skeletal

tetany/cramp/pins and needles

Question 25

why are patients more prone to osteoporosis in hyperparathyroidism?

Answer 25

PTH increases osteoclasts which break down bone

Question 26

commonest cause of raised Ca?

Answer 26

primary hyperparathyroidism

Question 27

3 findings needed for a diagnosis of primary hyperparathyroidism?

Answer 27

raised serum Ca raised PTH raised urine Ca excretion

Question 28

most common cause of primary hyperparathyroidism?

Answer 28

adenoma of the parathyroid gland

Question 29

management of hyperparathyroidism?

Answer 29

high fluid intake low Ca/vit D diet surgery of adenoma if serious symotoms

Question 30

why do patients get hypoparathyroidism?

Answer 30

lack of cells secreting PTH

Question 31

what is di george syndrome?

Answer 31

condition causing congenital absence of the parathyroid glands

Question 32

how can autoimmune disease cause hypoparathyroidism?

Answer 32

destructs parafollicular cells

Question 33

what is chvosteks sign?

Answer 33

twitching of the facial muscle when gentle tapping is applied to the facial nerve

Question 34

what is trousseau's sign?

Answer 34

inflated blood pressure cuff causes tetany of the muscles of the hand and wrist

Question 35

why are hypoparathyroid patients still at a high fracture risk?

Answer 35

lack of bone remodelling due to low PTH

Question 36

treatment for hypoparathyroidism?

Answer 36

calcium/vit d supplements

Question 37

cause of pseudohypoparathyroidism?

Answer 37

genetic receptor abnormality leading to resistance of PTH

Question 38

why are PTH levels high in pseudohypoparathyroidism?

Answer 38

more is made to try to gain a response

Question 39

what hand abnormality is seen in pseudohypoparathyroidism?

Answer 39

blunting of digit 4

Question 40

what 2 problems can stop vitamin D from being ACTIVATED and why?

Answer 40

liver/kidney failure as these are where the enzymes that activate it are

Question 41

what happens to PTH levels when vitamin D is low?

Answer 41

will increase to maintain normal serum Ca

Question 42

why can bone become soft?

Answer 42

low vitamin D causes lack of mineralisation of bone

Question 43

how can you tell osteomalacia and rickets apart?

Answer 43

bone is NOT deformed | DO have a gait abnormality due to proximal myopathy

Question 44

what does a T score in a DEXA scan compare?

Answer 44

bone mineral density to the mean result of a young adult female population

Question 45

what does a Z score in a DEXA scan do?

Answer 45

mean bone mineral density compared to females of the same age

Question 46

what BMD values indicate osteopenia?

Answer 46

>1 but under 2.5 standard deviations below the young adult mean

Question 47

what BMD values indicate osteoporosis?

Answer 47

>2.5 standard deviations below the young adult mean

Question 48

oily fish is rich in what vitamin?

Answer 48

D

Question 49

what further investigations should be done into osteoporosis to figure out the cause?

Answer 49

``` bone biochem coeliac antibodies protein electrophoresis PTH levels testosterone ```

Question 50

is weight bearing or non weight bearing exercise better for osteoporosis?

Answer 50

weight bearing (preserves bone density)

Question 51

what do bisphosphonates do?

Answer 51

anti-resorptive ie they inhibit osteoclast activity

Question 52

main bisphosphonate taken by patients?

Answer 52

alendronate

Question 53

effect of an addisonian crisis on Na and K?

Answer 53

low Na | high K

Question 54

what should always be in the differential for someone with tachycardia and hypotension?

Answer 54

sepsis

Question 55

what 3 things are used to manage an addisonian crisis?

Answer 55

glucose IV fluids steroid replacement eg hydrocortisone

Question 56

main iatrogenic cause of an addisonian crisis?

Answer 56

taking a patient immediately off a long term steroid course

Question 57

when is the only time that a short synacthen test would be inaccurate?

Answer 57

immediately post acute pituitary apoplexy

Question 58

what are sick day rules?

Answer 58

if the patient is ill one day they should double their dose for that day

Question 59

why does a lesion in the pituitary stalk cause increased prolactin?

Answer 59

inhibits dopamine transmission from the hypothalamus

Question 60

why would you experience postural hypotension in hypopituitarism?

Answer 60

lack of ACTH release stops mineralocorticoid (eg aldsterone) production

Question 61

what would TFTs look like in someone with hypopituitarism?

Answer 61

low or normal TSH | low T4

Question 62

why are T4 levels low in hypopituitarism?

Answer 62

lack of TSH from the pituitary

Question 63

commonest cause of hypopituitarism?

Answer 63

pituitary tumour

Question 64

infective causes of hypopituitarism?

Answer 64

meningitis syphilis encephalitis

Question 65

treatment for hypopituitarism?

Answer 65

HRT eg thyroxine, steroids, testosterone

Question 66

what is TRAB?

Answer 66

TSH receptor antibodies