Calcium disorders

Question 1

What triggers secretion of PTH?

Answer 1

Low serum calcium levels or high phosphate

Question 2

Actions of PTH?

Answer 2

Increased Ca absorbed in the distal tubule
Activates Vit D to give more calcium absorbtion
increased osteoclast activity to release ca from bone

Question 3

Overall effect of increased PTH?

Answer 3

Increased Serum Ca and decr. phosphate

Question 4

how is PTH regulated?

Answer 4

Transcription is inhibited by activated vit D

Translation is inhibited by serum CA

Question 5

Where do we get Vit D from?

Answer 5

Diet: oilky fish, eggs

UV radiation: 7 dihydrocholesterol -> Vit D

Question 6

Where is vit D hydroxylated?

Answer 6

first one is in the liver, second requires PTH in the kidney

Question 7

What does the vit d assay look for?

Answer 7

25 oh D3, active frm is rarely measured

Question 8

what does calcitonin do?

Answer 8

produced by thyroid C cells and released in hypercalcaemia. Inhibits resorption of bone by acting on osteoclasts, NOT essential to life

Question 9

3 types of cell in bone?

Answer 9

osteoblast, marker is carbonic anhydrase

osteoclast, marker is alk phos

osteocyte

Question 10

Normal calcium range

Answer 10

2.25-2.5

Question 11

Presentation of hypercalcaemia?

Answer 11

Polyuria and polydipsia
dyspepsia ( releases gastrin)
depression
mild cognitive impairment
-
Muscle weakness, constipation, anorexia
-
abdo pain, vomiting, dehydration, lethargy, shortened QT, coma, pancreatitis

renal stones and ulcers

Question 12

Causes of Hypercalcaemia?

Answer 12

Common: HYperPTH
Malignancy- myeloma, mets, humoral hypercalaemia

Less common- vit D intoxication, familial hypocalciuric hypercalaemia, sarcoid,

Uncommon- thiazides, lithium, renal failure, vit A, milk alkali

Question 13

Ix in Hypercalcaemia?

Answer 13

corrected calcium (tends to be longstanding and lower if non malignant)
PTH

FOr underlying illness: cxr, bloods, Vit D, protein incl. serum electrophoresis, cortisol

end organ damage: renal US, skeletal radiographs. bone tumour markers

Question 14

DIfferent types of hyperPTH?

Answer 14

1o: excessive secretion by gland, 80% are a single adenoma with 0.5% ca, association with MEN
2o: PT glands increase in activity due to low ca2+. chronic renal failure is the most common cause but also drugs such as lithium, thiazides- hypo as cannot activate vit D (kidneys fucked)
3o: usually when renal disease is corrected, hyperplasia then get hypercalcaemia when fixed. more likely to have hyper

Question 15

Signs of hyper PTH?

Answer 15

relate to ca or asymptomatic
weak, tired, depressed, thirsty
renal stones, abdo pain, duodenal ulcers
bone pain, #, osteoporosis
check in hypertention

Question 16

What can you see on imaging of hyperPTH?

Answer 16

osteitis fibrosa cystica (rare(, subperiosteal erosions, cysts, pepper pot skull in 3o

Question 17

ix in hyperPTH?

Answer 17

diagnostic is high PTH in high/normal Ca
24hr urine collection will show raised ca, unless familial hypocalciuric hypercalcaemia

U+Es
Abdo kub for renal stones
dexa for osteoprosis

Question 18

aim of ix in hyperPTH?

Answer 18

identify end organ damage and see candidates for surgery

Question 19

Diagnosis of 1o PTH?

Answer 19

Ca>2.65
U+Es normal
Not on lithium or thiazide
PTH>3
24hy urinary CA >2.5

Question 20

Management of hyperPTH?

Answer 20

observation in mild disease, see 6 monthly, increase fluid intake and avoid thiazides.

Medical: cinacalet (calcimomimetic) increases senstivity of cells to CA so PTH goes down (s/e myalgia and low test)

Surgery: prevents ulcers and fractures.

Question 21

Indications for surgery in hyperPTH?

Answer 21

high serum ca
high urinary
bone disease
renal calculi
decr. renal fx
<50

Question 22

Complications of parathyroidectomy

Answer 22

metabolic: hypoparathyroid
hypocalcaemia

mechanical: tracheal compression from haematoma
r. laryngeal n damage

recurrance is 8% in 10 yr

Question 23

Malignant hyperPTH?

Answer 23

PTrP is secreted by some squamous cell lung cancers and breast and renal. mimcs pth so incr, ca. PTH appears low as not detected on assay

Question 24

Familial hypocalciuric hypocalcemia?

Answer 24

AD condition, reduced sensation to ca so think ca is normal when is actually high
generally benign and asymptomatic
dont benefit from surgery

Question 25

Factors suggesting hypercalcaemia of malignancy?

Answer 25

low pth
low albumin
high alk phos
raised PTrP 
increased PTH

Question 26

Management of acute hypercalcaemia~?

Answer 26

Correct dehydration with saline
bisphosphonates- pamindronate slowly infused. 2-3 days to work, max effect 1 week
steroids are used in sarcoid eg pred 40-60mg
cemo may help in malignancy