CP 52 - Disorder of Calcium, Phosphate & Magnesium

Question 1

What chemical property does calcium have?

Answer 1

Divalent cation - Ca2+

Question 2

why is calcium important physiologically?

Answer 2

Muscle contraction, neuronal excitation, enzyme activity (Na/K ATPase, hexokinase), Blood Clotting

Question 3

Why is calcium structurally important?

Answer 3

key component of hydroxyapatite - Ca10(PO4)6(OH)2 - predominant mineral in bone

Question 4

How is calcium used in blood clotting

Answer 4

calcium is being caught by anti-coagulant so can not be used for clotting.

Question 5

What chemical property does phosphate has?

Answer 5

Monovalent anion - Po4-

Question 6

why is phosphate important physiologically?

Answer 6

The P in ATP, intracellular signalling, cellular metabolic process eg glycolysis

Question 7

Why is phosphate structurally important?

Answer 7

backbone of DNA, component of hydroxyapatite - ca10(PO4)6(OH)2, Membrane phosholipids

Question 8

is phosphate intracellular/extracellular

Answer 8

intracellular

Question 9

What chemical property does magnesium have?

Answer 9

Divalent Cation - Mg2+

Question 10

why is magnesium important physiologically?

Answer 10

cofactor for ATP (important), neuromusclar excitability, enzymatic function, regulates ion channels

Question 11

Why is magnesium structurally important?

Answer 11

comprises 0.5% -1& of bone matrix

Question 12

which ion does alk phos rely on?

Answer 12

Zinc

Question 13

what are the 4 things which are related to unbalanced homeostasis

Answer 13

intake from guts, storage in bone, excretion/loss from intestines & kidneys, tissue redistribution of ions

Question 14

normal range of calcium?

Answer 14

2.20.2.60 mmol/L

Question 15

what are the 2 controlling factors for calcium

Answer 15

PTH, Vit D and metabolites

Question 16

what are the 3 complex reaction between calcium with?

Answer 16

GI uptake of Ca2+, Renal clearance & bone as storage

Question 17

Total Ca = ?

Answer 17

Total Ca = ionised Ca + bound Ca+ complexed Ca

Question 18

what is ionised ca

Answer 18

physiologically active fraction eg ca sensing receptor, cellular effects, regulation of PTH

Question 19

what is bound ca?

Answer 19

physiologically inactive eg albumin main binding protein ~ 50%

Question 20

what is complexed ca?

Answer 20

salts eg calcium phosphate & calcium citrate

Question 21

what is routine measurement for Ca?

Answer 21

total calcium (but does not reflect ionised calciu)- cost effective & convenience

Question 22

what factor affect Ca?

Answer 22

total Ca - by [albumin], ionised Ca - by pH

Question 23

what compete for albumin binding site with Ca?

Answer 23

H+ ions - acidosis - reduces Ca-albumin, Alalosis - increase Ca-albumin

Question 24

what disorders can affect ca conc?

Answer 24

PTH, Vit D, Bone Metastases, GI tract - malabsorption, kidney & diet

Question 25

what is the amount of Ca present in bone

Answer 25

25Mol - 99% of the whole body's conc

Question 26

what is the role of oestrogen for ca absorption?

Answer 26

oestrogen stimulates Ca reabsorption in the kidney

Question 27

what does FGF23 stimulate?

Answer 27

it stimulate the phosphate excretion (by decreaseing phosphate reabsorption)

Question 28

Which UV light is absorbed to be used or Vit D production?

Answer 28

UV-B

Question 29

What form of Vit D is produced in the skin?

Answer 29

D3

Question 30

what enzyme convert D3 in the liver?

Answer 30

25-Hydroxylase

Question 31

What form of Vit D is produced in liver?

Answer 31

25(OH)D3

Question 32

where is 25(OH)D3 transported to after being produced in the liver?

Answer 32

kidney

Question 33

what form of Vit D is produced in the kidney?

Answer 33

1,25(OH)2D3

Question 34

which organ does PTH take effect to affect production of Vit D ?

Answer 34

Kidney

Question 35

what is the role of PTH have on production of Vit D?

Answer 35

PTH essential for production of Vit D as it convert the inactive form of Vit D - 25(OH)2 D3 into 1,25(OH)2D3

Question 36

what is the physiological function of 1,25(OH)2D3

Answer 36

essential for Ca and PO4 absorption, increase bone mineralisation, induces differentiation of immune cells, inhibts proliferation of tumor cells, induces differentiation of tumor , inhibits angiogenesis

Question 37

What does increase in 1,25(OH)2D3 do to your body?

Answer 37

decrease production of PTH

Question 38

what are the uses of PO4 & Ca to the kidney?

Answer 38

PO4 & Ca are correlated to the production of active form of Vit D

Question 39

what is calcium - PTH loop?

Answer 39

PTH - (+) - bone, gi & kidney (uptake & reabsorption) - Ca - (-) - PTH production.

Question 40

what are the relationship between Vit D and BMi

Answer 40

Vit D is hydrophobic & can deposit in the adipose tissue

Question 41

What are the causes of hypocalcaemia?

Answer 41

hypoproteinaemia, Vitamine D deficiency (dietary/malabsorption), hepatic disease, renal disease, diabetes, hypoparathyroidism (1o & 2o to mg depletion), pseudohypoparathyroidism (End organ PTH resistance)

Question 42

Causes of hypercalcaemia?

Answer 42

hyperparathyroidism, malignancy, drugs, vit D excess (1aplha cholecalciferol, sarcoidossi), bone disease+ immobilisation

Question 43

what is adjusted calcium?

Answer 43

Ca conc accounted for changes in albumin

Question 44

what is the formula for adjusted ca?

Answer 44

adj ca = total ca +(40- Alb)X0.025

Question 45

what does high Cac & PTh and low Pi indicate?

Answer 45

1o hyperparathyroidism

Question 46

what does high ca and low PTH indicate?

Answer 46

malignancy

Question 47

What are the causes of phosphate deficiency?

Answer 47

hyperparathyroidism, excess loss (renal tubular damage, GI loss, diabetes -diuresis), poor intake (malnutrition, inadquate IVN), ECF/ICF redistribution

Question 48

symptoms of phosphate deficiency?

Answer 48

Haemolysis, thrombocytopenia, ppor granulocyte function, severe muscle wakness, respiratory muscle failure, confusion, irrability and coma, renal dysfunction

Question 49

what is treatment of phosphate deficiency?

Answer 49

IV fluid including TPN (total parental nutrient) formulations

Question 50

What are hypomagnesaemia associated to?

Answer 50

hypokalaemia, hyponatraemia(Na+), hypophosataemi, hypocalcemia

Question 51

Causes ofMagnesium depletion?

Answer 51

renal disease, hypercalcaemic states, drugs eg diuretics,cisplatin(chemotherapty), antibiotics (gentamicin), GI tract malabsorption problems

Question 52

Effects of magnesium depletion

Answer 52

cellular - reduced mitochondrial respiration, impaired phosphrylation, defective NA-K ATPase activity, Biochemical - hypocalcaemia, hypophosphataemia, hypokalaemia, Endocrine - impaired PTH release, PTH resistance in bone, CVS - cardiac irritability, reduced contractility, CNS - hyperreflexia, tetany, Muscle - weakness, muscle fibrilliation

Question 53

what is good indication for Mg level in the body

Answer 53

leucocyte Mg - good correlation, good predictive value