Disorders of Calcium, phosphate and magnesium Flashcards Preview

Clinical Pathology > Disorders of Calcium, phosphate and magnesium > Flashcards

Flashcards in Disorders of Calcium, phosphate and magnesium Deck (31):
1

Why is calcium physiologically important?

Muscle contraction
Neuronal signalling
Coagulation
Enzyme activity

Key mineral component of bone (hydroxyapatite)

2

What is the importance of phosphate?

ATP
Intracellular signalling
Cellular metabolic process
Backbone of DNA

INTRACELLULAR

3

What is the importance of magnesium?

Cofactor for ATP
Neuromuscular excitability
Enzyme fucntion
Ion channel regulation

INTRACELLULAR

4

What mechanisms are involved in homeostasis of ions?

-Storage
-Tissue redistribution
-Intake (dietary)
-Excretion

5

What are the key factors that control calcium levels?

PTH
Vit D

6

What is the only fraction of calcium that is physiologically active?

Ionised calcium

7

What other forms of calcium are there?

Bound calcium e.g. to albumin

Complexed - salts e.g. calcium phosphate, calcium citrate

8

What is the normal range for total calcium>

2.2-2.6 mol/L

9

What is the distribution for physiologically active Ca and inactive (i.e.bound/complexed)

50:50

10

How does alkalosis and acidosis change proportion of bound calcium?

Alkalosis - increased calcium-albumin, reduced ionised calcium

Acidosis - reduced calcium-albumin, increases ionised calcium

Because H+ ions compete with Ca++ for albumin binding sites

11

What can alkalosis cause?

Tetany - increased ionised calcium

12

What are the endogenous factors for vit D

Endogenous - skin colour, ageing

13

What are the exogenous factors for vit D

Ozone, sunscreen and clothing (cultural), season, time of day, supplements

14

What else does fit D fall with?

Age
BMI
body fat

15

Whats effect does PTH have on the gut?

Increased vit D release from kidney

Increased bit D increases calcium absorption from gut

16

What effect does PTH have on the kidney?

Reduced calcium clearance but increase phosphate excretion

17

What effect does PTH have on bones?

Increased bone turnover with net reabsorption

18

What its the plasma Ca?

Total Ca = ionised calcium + bound calcium + complexed calcium

19

What is magnesium required for?

Release of PTH from zymogens

20

What are the causes for hypocalcaemia?

Hypoproteinaemia - reduced album

Reduced vit D - dietry/malabsorption, hepatic/renal disease, end organ bit D resistance

Hypoparathyroidism - primary, secondary - Mg deficiency

Inadequate intake of calcium

21

What does a low Ca but high PTH indicate?

Vit D deficiency

22

What does a low Cal, high phosphate and low PTH indicate?

Hypothyroidism (primary or secondary to magnesium def)

23

What are the simple clinical features of hypercalcaemia?

Stones bones (pain) moans (ab pain) and groans (load mood/depression)

24

What are the causes of hypercalcaemia?

Hyperparathyroidism
Malignancy e.g. primary tumour of PT
Bone disease and immobilisation
Excessive vit D
Drugs e.g. lithium

25

If you have high Ca, high PTH and low phosphate, whats the cause?

Hyperparathyroidism

26

If you have high calcium and low PTH, whats the cause?

Bone malignancy

27

What are the main causes of phosphate deficiency?

-Hyperparathyroidism
-Excess losses - renal tubule damage, GI, diabetes (diuresis)
- Insufficient intake - malnutrition
ECF/ICF redistribution e.g. refeeding

28

What are the symptoms of phosphate deficiency?

-Haemolysis, thrombocytopenia, poor granulocyte function

- Muscle weakness, resp muscle failure, rhabdomyolysis

- confusion/irritability

29

What is hypomagnesaemia associated with?

Hypokalaemia
Hyponatraemia
Hypophosataemia
Hypocalcaemia

LOOK AT THESE!!!

30

What is the major causes of hypomagnesaemia?

Renal - acute tubular necrosis
Hypercalaemic states
Drugs e.g. antibiotics, diuretics
GI - malnutrition, diarrhoea, malabsorption

31

What are the effects of magnesium depletion?

Cofactor of ATP - so anything requiring ATP in effected!

Impaired PTH release - required for PTH release from zymogens

Decks in Clinical Pathology Class (50):