Calcium Control

Question 1

What is the normal range for calcium in the plasma?

Answer 1

2.2 to 2.6 mmol/L

Question 2

What proportion of the calcium in the blood is free?

Answer 2

45%

Question 3

What proportion of the plasma calcium is bound to albumin?

Answer 3

50%

Question 4

What two hormones are involved in calcium metabolism?

Answer 4

PTH

• increased tubular hydroxylation of vitamin D
• Mobilises calcium from bone
• Increase renal calcium resorption
• Increased renal phosphate excretion

Calcitriol

• Increased calcium and renal absorption from the gut
• Bone remodelling

Question 5

How does vitamin D get activated?

Answer 5

D3 in the skin goes to the liver, where it is converted into 25(OH)D3 by 25 hydroxylase. It then is transported to the kidney where it is converted into 1,25(OH)2D3 by 1 alphahydroxylase. This is the active form of vitamin D.

Question 6

Name causes of hypocalcaemia

Answer 6

• Hypoalbuminaemia
• Chronis kidney disease
• Hypomagnesaemia
• Osteomalacia/ricket’s
• Acute pancreatitis
• Overhydration

Question 7

What are the symptoms of hypocalcaemia?

Answer 7

• Perioral parasthesia
• Carpopedal spasm
• Neuromuscular excitability

Question 8

How is hypocalcaemia treated?

Answer 8

• Give calcium if mild
• Chronic kidney disease: alfacalcidol
• Severe: 10% calcium gluconate IV

Question 9

What are the symptoms of vitamin D deficiency?

Answer 9

Adults:

• Bone or muscle pain
• Increased risk of fractures

Children:

• Bowing of the long bones
• Myopathy

Question 10

What are the expected levels (relative to normal) of Ca, PO4, PTH, AlkPhos and VitD in primary hyperparathyroidism?

Answer 10

Calcium: high
Phosphate: low
PTH: high
Alkaline Phosphatase: high
Vitamin D: normal

Question 11

What are the expected levels (relative to normal) of Ca, PO4, PTH, AlkPhos and VitD in secondary hyperparathyroidism?

Answer 11

Calcium: low
Phosphate: high
PTH: high
Alkaline Phosphatase: high
Vitamin D: normal

Question 12

What are the expected levels (relative to normal) of Ca, PO4, PTH, AlkPhos and VitD in tertiary hyperparathyroidism?

Answer 12

Calcium: high
Phosphate: low
PTH: high
Alkaline Phosphatase: high
Vitamin D: normal

Question 13

What are the expected levels (relative to normal) of Ca, PO4, PTH, AlkPhos and VitD in hypoparathyroidism?

Answer 13

Calcium: low
Phosphate: high
PTH: low
Alkaline Phosphatase: low
Vitamin D: normal

Question 14

What are the expected levels (relative to normal) of Ca, PO4, PTH, AlkPhos and VitD in osteomalacia/ricket’s?

Answer 14

Calcium: low
Phosphate: low
PTH: high
Alkaline Phosphatase: high
Vitamin D: low

Question 15

What are the expected levels (relative to normal) of Ca, PO4, PTH, AlkPhos and VitD in Paget’s disease?

Answer 15

Calcium: normal
Phosphate: normal
PTH: normal
Alkaline Phosphatase: high
Vitamin D: normal

Question 16

What are the expected levels (relative to normal) of Ca, PO4, PTH, AlkPhos and VitD in osteoporosis?

Answer 16

Calcium: normal
Phosphate: normal
PTH: normal
Alkaline Phosphatase: normal
Vitamin D: normal

Question 17

What are the symptoms of hypercalcaemia?

Answer 17

• Polyuria and polydipsia
• Renal stones
• Bone pain
• Psychiatric disturbances
• Abdominal pain
• Muscle weakness

Question 18

Name some causes of hypercalcaemia

Answer 18

• Dehydration
• Primary hyperparathyroidism
• Tertiary hyperparathyroidism
• Malignancy
• Excess vitamin D
• Sarcoidosis
• Thyrotoxicosis

Question 19

How is hypercalcaemia treated?

Answer 19

• Fluids
• Fluids
• Fluids
• Correct cause
• Malignancy pts will get bisphosphonates to help with bone pain