Calcium Metabolism Extra

Question 1

What are the cellular roles of phosphate?

Answer 1

• Membrane phospholipid structure
• ATP
• Protein phosphorylation
• Bone formation
• Genetic information

Question 2

How is calcium absorption from GI tract regulated?

Answer 2

Controlled by hormones and is dependent on the Ca2+ status of body

Question 3

What are the blood test results for hypercalcaemia?

Answer 3

Serum Ca2+ above 2.6 mmol/L

Alkaline phosphatase > 120

Question 4

What is alkaline phosphatase?

Answer 4

• Enzyme present on osteoblasts in plasma
• Marker of bone turnover
• High plasma levels = increased bone formation

Will occur in cancer as more bone broken down means that more bone has to form

Question 5

How can malignancy cause hypercalcaemia?

Answer 5

• Haematological malignancies

- Production of parathyroid hormone related peptide

Question 6

How does PTHrP act?

Answer 6

• Binds to parathyroid hormone

- Does not increase C-1 hydroxylase

Question 7

How is vitamin D activated?*

Answer 7

Slide 16

Question 8

What is calcitonin?

Answer 8

Peptide hormone produced by the parafollicular cells of the thyroid gland that is secreted in response to high level of plasma Ca2+ and in response to GI hormones

Question 9

Summary of effects of hormones involved in Ca2+ and phosphate balance?

Answer 9

Slide 19