BT_PO 1.88 Outline the regulation of plasma calcium including the actions and control of vitamin D, parathyroid hormone and calcitonin
T / F of the total calcium in plasma, 20% is present in the free ionised form
T / F a decrease in plasma calcium causes the release of parathyroid hormone
T / F PTH acts by directly (i) releasing calcium from bone, (ii) increasing calcium absorption from the GIT, and (iii) decreasing renal calcium excretion
T / F vitamin D is converted to 1,25-dihydroxy cholecalciferol by UV light, which then acts to increase calcium absorption from the GIT
T / F hypocalcaemia can prolong the QT interval
T / F 10 mL of 10% calcium chloride contains 6.8 mmol Ca++, and 10 mL of 10% calcium gluconate contains 2.2 mmol Ca++
Extra discussion questions:
- Following a total thyroidectomy, patients can develop hypocalcaemia. Can you explain why? What symptoms would develop, and what physiology explains these?
- Patients with bony metastases can develop hypercalcaemia. What is the mechanism of this? What symptoms would develop, and what physiology explains these?