Disorders of Calcium, Phosphate and Magnesium (Endocrine system)

Question 1

Why is calcium physiologically important?

Answer 1

• muscle contraction
• neuronal excitation
• enzyme activity
• blood clotting

Question 2

Why is Phosphate physiologically important?

Answer 2

• required for ATP

- intracellular signalling

Question 3

Why is Magnesium physiologically important?

Answer 3

• cofactor for ATP
• neuromuscular excitability
• enzyme function
• regulates ion channels

Question 4

What are the 4 factors / pillars of homeostasis?

Answer 4

1) Intake
2) Storage
3) Excretion / loss
4) Tissue Redistrabution

Question 5

What are the 2 controlling factors of calcium levels?

Answer 5

1) ParaThyroid Hormone

2) Vitamin D

Question 6

Which fraction of the total plasma calcium is physiologically active?

Answer 6

• the ionised fraction
  (it is fundamental for the release of PTH)

Total Ca = Ionised + bound + complexed.

When calcium is bound to albumin it cannot interact in reactions/

Question 7

What is the effect of Acidosis on the fraction of bound calcium?

Answer 7

Acidosis reduces the amount of bound calcium and increases the fraction of ionised calcium

Question 8

What is the effect of alkalosis of the fraction of bound calcium?

Answer 8

Alkalosis increases the bound calcium and decreases ionised calcium

Question 9

What could affect the levels of calcium in the blood?

Answer 9

1) PTH and Vitamin D
2) Bone Metastases
3) GI (malabsorption)
4) Kidney (excess excretion / reabsorption)
5) Diet

Question 10

What is the role of Magnesium and PTH?

Answer 10

Magnesium helps PTH to be secreted from the para thyroid gland

Question 11

What are the causes of HYPOcalcaemia?

Answer 11

• Hypoproteinaemia (Ca binds to protein)
• Vit D deficiency
• HypoParaThyroidism
• inadequate intake of Calcium.

Question 12

What are the causes of HYPERcalcaemia?

Answer 12

• HyperParaThyroidism
• Malignancy (lytic)
• Drugs
• Vit D excess

Question 13

What are some of the causes of Phosphate deficiency?

Answer 13

• HyperParaThyroidism
• Excess loss via renal tubular damage, GI (not absorbed), diabetes.
• Poor intake

Question 14

What are some the of the symptoms of phosphate deficiency?

Answer 14

• Haemolysis
• Thrombocytopenia
• muscle weakness
• respiratory muscle failure
• confusion / irritability

Question 15

What are the causes of Magnesium depletion?

Answer 15

Renal (excretion)
Drugs
GI (malabsorption)
Insufficient intake

Question 16

What are the effects of Mg depletion?

Answer 16

• reduced respiration
• impaired DNA synthesis
• Hypocalcaemia (as Mg stimulates release of PTH)
• cardiac irritability
• CNS problem
• Muscle weakness