hypocalcaemia

Question 1

albumin in alkalosis

Answer 1

tends to be negatively charged
calcium is more likely to latch onto calcium
more bound calcium and less free ionised calcium
total calcium is the same
may lead to symptoms of hypocalcaemia

Question 2

hypoalbuminaemia

Answer 2

free ionised calcium stays the same due to hormonaal regulation
less total calcium due to less. bound calcium
false/psuedo hypocalcaemia

Question 3

less calcium entering the blood

Answer 3

hypoparathyroidism - caused by surgical removal or autoimmune destruction, congenital problems or deficiency in magnesium
low vitamin D

Question 4

things causing low vit D

Answer 4

deficient diet
malabsorption
cirhhosis
lack of sunlight
chronic renal fialure

Question 5

things causing hypoparathyroidsim

Answer 5

magnesium deifiency (need this to make parathyroid hormone)
congenital problems eg. di george syndrome
autoimmune destruction
surgical removal

Question 6

to much calcium leaving the blood

Answer 6

too much ionised calcium gets excreted
eg. in kidney failure because the nephron doesnt effectively reabsorb calcium
tissue injury - burns, rhabdomyalysis, tumour lysis syndrome
inflammatory. processes - acute pancreatitis

Question 7

why does tissue injury cause hypocalcaemia

Answer 7

cells die and release. intracceullar phosphate into the blood
phosphate binds calcium and makes it insoluble in the blood
effectively decreasing calcium in blood

Question 8

why does inflammation cause hypocalcaemia

Answer 8

eg. acute pancreatitis
free fatty acids binds ionised calcium which precipitates out

Question 9

blood transfusions

Answer 9

blood transfusions can cause chelation
bind with calcium
forms complex calcium which is an inactive molecule

Question 10

tetany

Answer 10

involuntary muscle contraction
happens in hypocalcaemia

Question 11

chvostek’s sign

Answer 11

facial muscles twitch

Question 12

troussaes sign

Answer 12

blood pressure cuff cause a relfex

Question 13

other symptoms of hypocalcaemia

Answer 13

muscle cramps
abdominal pain
perioral tingling
seizures

Question 14

diagnosis of calcaemia

Answer 14

ECG may show prolonged QT
hypocalcaemia in blood
parathyroid hormone labs
vit D, albumin, phosphorus, magnesium

Question 15

factitious hypocalcaemia

Answer 15

asymptomatic. decrease in total calcium with a normal ionised calcium level
typically occurs due to low serum albumin

Question 16

causes of hypoptroteinaemia

Answer 16

nephrotic syndrome, liver cirrhosis, severe malnutrition. malabsorbtion

Question 17

function of parathyroid hormone

Answer 17

kidneys: incraesed calcium resorbtion, decreases phosphate resorbtion, increases vit D production
GI: increases calcitriol (vit D) synthesis which increases calcium absorbtion
bone: releases calcium and phosphate brom the bones

Question 18

what does parathyroid hormone do in bone

Answer 18

increases expression of RANKL on osteoblasts
RANKL binds osteoclastic RNK receptor, which increases osteoclast activity, and results in increase bone resorption and calcium release

Question 19

caalcitriol

Answer 19

A form of vitamin D that becomes hormonally active in the kidneys. Increases calcium absorption in the small bowel and renal tubules and increases calcium release from bones.

Question 20

PTH secretion is stimulated by

Answer 20

decrease in serum Ca
hyperphosphataemia
mild hyppomagnesaemia
low calcitriol levels

Question 21

PTH secretion is inhibited by

Answer 21

increase in serum Ca
marked hypomagnesaemia

Question 22

action of calcitriol

Answer 22

GI: increases calcium and phosphate absorption
kidneys: increases calcium and phosphate resorption
bone: enhances bone mineralisation

Question 23

calcitonin action

Answer 23

opposes the effects of PTH
inhibits bone resorption, decreasing serum calcium

Question 24

what triggers calcitonin scretion

Answer 24

increase in serum Ca

Question 25

what is calcitonin

Answer 25

A hormone produced by parafollicular cells (C cells) in the thyroid gland that inhibits osteoclast activity and renal reabsorption of calcium and phosphate to reduce serum calcium; it may be used therapeutically, e.g., in osteoporosis, or diagnostically, as it is often elevated in medullary thyroid cancer.

Question 26

neurological manifestations of hypocalcaemia

Answer 26

tetany
parasthesis
spasms
chvostek sign: twitching of the facial muscles ellicited by tapping the facial nerve below and iin fron to fhte ear
trousaeu sign: spasm occuring after iinflation of te pressure cuff
seizure

Question 27

cardiovascular manifestaations

Answer 27

congestiva heart failure (hypocalcaemia may lead to myocardial dysfunction)
hypotension
cardiac arrythmias (prolonged QT)

Question 28

manifestations of chronic hypocalcaemia

Answer 28

physiatric manifestations
opthalmological manifestations
dental changes: altered morphology, dental enamel hypoplasia
growth plate abnomrlaities

Question 29

diagnsotics

Answer 29

diagnostics should not delay treatment - acute symptomatic hypocalcaemia may be fatal
confimr hypocalcaemia - measure total and ionised calcium, check serum albumin
electrolyte abnormalities - BMP, serum phosphate and magnesium
serum intact PTH

Question 30

serum intact PTH

Answer 30

low or normal: suggests hypoparathyroidism
high: suggests parathyroid function is preserved

Question 31

why is a normal level of PTH in hypocalcaemia considered low

Answer 31

When serum calcium is low, the physiological response for the parathyroid gland is to secrete more PTH; therefore, a PTH value within normal laboratory range is considered inadequately low in hypocalcemia.

Question 32

aetiologies of hypocalcaemia when PTH is high

Answer 32

hyperphosphataemia (high phosphate)
chronic kidney disease (high phosphate and high creatinine)
malaborbtion (low magnesium)
vit D deficeincy

Question 33

findings on fundoscopy

Answer 33

papilloedema

Question 34

mainstay of hypocalcaemia therapy

Answer 34

calcium supplimentation and treatment of underlying caause

Question 35

for severe or symptomatic hypocaalcaemia

Answer 35

eg. with tetany, seizures, prologed QT interval
IV calcium supplimentation
continuous telemetry - IV calcium can trigger life threatening arrythmias in patients simultaneously receieving cardiac glycosides (digoxin or digitoxin)

Question 36

loop diuretics

Answer 36

loop duiretics lose caclium
lose them in hypocalcaemia

Question 37

CKI effect on calcium

Answer 37

hypocalcaemia
decreased renal hydroxylation of Vit D, reduced calcium absorbtion in the gut, decreased renal excretion of phosphate, hyperphosphhataemia, caclium phosphate precipitation in tissues

Question 38

milk-alkali syndrome

Answer 38

A syndrome caused by excessive consumption of calcium and absorbable alkali (most commonly calcium carbonate). Presents with hypercalcemia, metabolic alkalosis, and acute kidney injury.

Question 39

bisphosphonates

Answer 39

Bisphosphonates such as zoledronic acid reduce serum calcium levels by reducing osteoclast-mediated bone resorption and are considered first-line in malignancy-associated hypercalcemia.