Calcium Homeostatsis

Question 1

How does parathyroid gland know when to secrete PTH?

Answer 1

Calcium sensing receptor changes shape to different levels of calcium in blood

Question 2

Low magnesium prevents?

Answer 2

PTH release

Question 3

PTH works on?

Answer 3

PTH type 1 receptor

Question 4

Where are PTH1 receptors?

Answer 4

Bone/kidney

Question 5

How does calcium release work?

Answer 5

PTH receptors on osteoblasts, then produces cytokines RANK ligand on rank receptor osteoclasts activation

Question 6

PTH causes in kidneys?

Answer 6

Increased calcium reabsorption

Decreased phosphate reabsorption

Question 7

What does hypocalcaemia do to neurons?

Answer 7

Destabilises

Make sure someone with seizures is checked for hypocalcaemia and hypoglycaemia

Question 8

Trousseau’s sign

Answer 8

Blood cuff above systolic, nerves fire more in hypocalcameia, hand cramps

Question 9

Chvostek’s sign

Answer 9

Tap face, facial nerve present, twitching of mouth

Low plasma calcium increases the permeability of neuronal membranes to sodium

Question 10

Hypercalcaemia consequences?

Answer 10

Abdominal pain
Thirst 
Polyuria
Musculoskeletal aches
Neurobehavioual symptoms
Renal calculus 
And osteoporosis

Question 11

40% of calcium is bound to proteins, which ones?

Answer 11

Albumin 90%

globulin 10%

Question 12

When does corrected albumin Ca not work?

Answer 12

Albumin conc over 20g/l

In severe acute illness

Question 13

Calcium level?

Answer 13

2.15 and 2.55 mmol/l

Question 14

Parathyroid glands have which cells?

Answer 14

Chief

Question 15

Osteoclasts releases?

Answer 15

H+
CATK
TRAP
And calcium

Question 16

In kidney PTH converts?

Answer 16

25OH vitamin D to 1,25 OH Vitamin D

Question 17

What does 1, 25 OH vitamin D do in gut?

Answer 17

Stimulates calcium transporters and Binding protein (calbindin) in gut cells cause greater absorption of calcium

Question 18

PTH is inhibited by?

Answer 18

1,25 OH vitamin D in chief cells

Question 19

Osteocytes cause inhibition?

Answer 19

have receptors for 1, 25 OH vitamin D and produce FGF 23 inhibit conversion of 25 to 1,25 vitamin D

Question 20

FGF23 causes?

Answer 20

Phosphate excretion

Question 21

Complications of hyperparathyroidism?

Answer 21

Osteoporosis and bone cysts

Question 22

Complications of hypercalcaemia?

Answer 22

Renal stones

Question 23

Indications of parathyroidectomy?

Answer 23

Osteoporosis
Renal calculus
Less than 50 years
Serum calcium over 2.8 mmol/l

Question 24

How to scan for parathyroid adenoma?

Answer 24

Ultrasound, sestamibi parathyroid scan (nuclear medicine scan)

Question 25

Hypoparathyroidism causes?

Answer 25

Iatrogenic- thyroidectomy, radical neck surgery Autoimmune Hypomagnesaemia Genetic mutations

Question 26

Secondary hyperparathyroidism?

Answer 26

Low serum 25 OH vitamin D, lack of sun exposure, GI problems and renal failure

Question 27

Rickets is when you have deficiency of

Answer 27

Vitamin D

Question 28

Osteomalacia?

Answer 28

Looser zones, small fractures lack of calcium

Question 29

Vitamin d deficiency increases risk of

Answer 29

Falls and fractures

Question 30

Hypocalcaemia can cause?

Answer 30

Seizures

Question 31

Trousseau sign?

Answer 31

Blood pressure cuff above systolic hand cramps

Question 32

Chvostek sign?

Answer 32

Tap on face near facial nerve twitching of the mouth

Question 33

What percent of calcium is bound to anions phosphate citrate?

Answer 33

10

Question 34

Parathyroid gland detects calcium through?

Answer 34

Calcium sensing receptor, change in shape

Question 35

Where does PTH bind?

Answer 35

PTH type 1 receptor

Question 36

Rapid ca2+ release in bone happens by?

Answer 36

Osteocytes squeezing out calcium

Question 37

If someone has a seizure what should you check?

Answer 37

Calcium because it can destabilise neurons

Question 38

Physical signs of hypocalcaemia?

Answer 38

``` Trousseasu’s sign- carpopedal spasm, cuff inflated over systolic Tetany Seizures Muscle cramps Bronchial spams Irritability Confusion Psychosis Parkinsonism ```

Question 39

In 10% of people with hypocalcaemia what is seen?

Answer 39

Chvostek’s sign- tap jaw where facial nerve is and the muscle will contract

Question 40

Consequences of hypercalcaemia?

Answer 40

Acute: thirst/polyuria Abdominal pain Constipation musculoskeletal aches weakness Neurobehavioural symptoms Renal calculus Osteoporosis

Question 41

How do parathyroid chief cells detect calcium?

Answer 41

Calcium sensing receptor

Question 42

When osteoclasts break down bone they release?

Answer 42

H+ CATK- cathepsin K TRAP- tartrate resistant acid phosphatase And calcium