Clinical Calcium Homeostatis

Question 1

what are the general functions calcium is needed for in the body

Answer 1

bone formation
cell division and growth
muscle contraction
neurotransmitter release

Question 2

what percentage of calcium is found in the intracellular fluid

Answer 2

0.9%

Question 3

what percentage of calcium is found in the extracellular fluid

Answer 3

0.1%

Question 4

in plasma, what proportion of calcium is bound to albumin

Answer 4

45%

Question 5

in plasma, what proportion of calcium is ionised

Answer 5

45%

Question 6

what is the normal range of plasma calcium

Answer 6

220-2.60 mMol/L

Question 7

what effect does increased albumin have on free calcium

Answer 7

increased albumin decreases free calcium

Question 8

what effect does decreased albumin have on free calcium

Answer 8

decreased albumin increases free calcium

Question 9

how do we calculate free plasma calcium if it is not 40g/l

Answer 9

Adjust Ca2+ by 0.1mmol/l for each 5g/l reduction in albumin from 40g/l

Question 10

what effect does acidosis have on ionised calcium

Answer 10

acidosis increases ionised calcium thus predisposing to hypercalcaemia

Question 11

what cells of the parathyroid gland secrete parathyroid hormone

Answer 11

cheif cells

Question 12

what triggers chief cells to produce PTH

Answer 12

chief cells respond directly to changes in calcium concentration. PTH os secreted in response to a fall in calcium

Question 13

what effects does PTH have on calcium at the renal tubules

Answer 13

promotes reabsorption of calcium from renal tubules

Question 14

what effect does PTH have on bone

Answer 14

promotes reabsorption of calcium from bone

Question 15

what effect does PTH have on vitamin D

Answer 15

converts vitamin D from its inactive form to active

Question 16

what neuromuscular clinical features may you find in acute hypocalcaemia

Answer 16

paresthesia
muscle twitching
seizures
laryngospasm/bronchospasm

Question 17

what cardiac clinical features may you find in acute hypocalcaemia

Answer 17

prolonged QT
hypotension
heart failure
arrythmia
papilloedema

Question 18

what clinical features may you find in chronic hypocalcaemia

Answer 18

ectopic calcification
extrapyramidal signs
dementia

Question 19

what can cause hypocalcaemia

Answer 19

disruption of parathyroid gland

severe vitamin D deficiency

Mg2+ deficiency

pancreatitis

Question 20

what can cause low parathyroid hormone

Answer 20

genetic disorders
post surgery
autoimmune

Question 21

what can cause high PTH

Answer 21

vitamin D deficiency
renal disease
pancreatitis

Question 22

when investigating hypocalcaemia what important things should be asked in the history

Answer 22

neck surgery
autoimmune disorders
ca2+ and Vit D intake

Question 23

what investigations should be done for hypocalcaemia

Answer 23

ECG
serum calcium
albumin 
phosphate
PTH
U&E's
Vit D
Magnesium

Question 24

what can cause hypoparathyroidism

Answer 24

digeorge syndrome
destruction
infiltration
reduced secretion PTH

Question 25

what is pseudohypoparathyroidism

Answer 25

disorder that presents in childhood, defined by target organ unresponsiveness to PTH

Question 26

what are Ca2+ PO4- and PTH levels in pseudohypoparathyroidism

Answer 26

low Ca2+ high PO4- elevated PTH

Question 27

severe hypocalcaemia is a medical emergency what level would Ca2+ be

Answer 27

<1.9mmol/l

Question 28

what is the treatment for severe hypocalcaemia

Answer 28

IV calcium gluconate

Question 29

what Ca2+ level in hypercalcaemia requires urgent treatment due to risk of dysrhythmia and coma

Answer 29

>3.5mmol/L (requires urgent correction due to risk of dysrhythmia)

Question 30

what are causes of hypercalaemia

Answer 30

primary hyperparathyroidism MEN syndromes tertiary hyperparathyroidism hypercalcaemia of malignancy Vit D intoxication

Question 31

what are clinical features of hypercalcaemia

Answer 31

polyuria polydipsia nephrolithiasis anorexia nausea&vomiting constipation muscle weakness

Question 32

what are neurological features of hypercalcaemia

Answer 32

decreased concentration fatigue confusion

Question 33

what are cardio features of hypercalcaemia

Answer 33

shortening of QT interval bradycardia hypertension

Question 34

what should be looked out for during examination in hypercalcaemia

Answer 34

signs of underlying malignancy

Question 35

what investigations should be done for hypercalcaemia

Answer 35

``` U&E's Ca2+ PO4- alk phosphate myeloma screen serum ACE PTH ```

Question 36

what are the causes of 90% of hypercalcaemia cases

Answer 36

primary hyperparathyroidism or tertiary hyperparathyroidism malignancy or drug causes

Question 37

what investigations should be done for hyperparathyroidism

Answer 37

U&E's check renal function check for kidney stones osteoporosis Ca2+, PTH, vit D

Question 38

what are the Indications for surgery in primary hyperparathyroidism

Answer 38

serum Ca2+ 0.25mmol/l above the normal limit osteoporosis eGFR<60 or presence of kidney stones if <50 years

Question 39

what is the treatment of primary hyperparathyroidism

Answer 39

generous fluid intake cinacalcet (leads to a fall in PTH and therefore Ca2+ levels)

Question 40

what is Familial Hypocalciuric | Hypercalcaemia

Answer 40

Autosomal dominant disorder of the calcium sensing receptor | benign disorder no therapy is needed

Question 41

what is the treatment of hypercalcaemia

Answer 41

rehydration-consider dialysis if severe renal failure after rehydration IV bisphosphonates

Question 42

Bisphophonates are often prescribed for osteoprosis, what is their effect on Ca2+ levels

Answer 42

Bisphosphonates act to inhibit bone resorption therefore they can cause hypocalcemia

Question 43

Multiple Endocrine Neoplasia (type 1 and 2) often presents with primary hyperparathyroidism true or false

Answer 43

true, MEN type 1 (95%) Men type 2 (20-30%)