Calcium and vitamin D Flashcards
Give the 5 main clinical indications for the use of calcium and vitamin D.
1) Osteoporosis
2) CKD
3) Severe hyperkalaemia
4) Hypocalcaemia
5) Vitamin D deficiency
Why are Calcium and vitamin D used in Osteoporosis?
To ensure a positive calcium balance when dietary intake and/or sunlight exposure are insufficient. Other treatments such as bisphosphonates may be given to reduce the risk of fragility fractures.
Why are calcium and vitamin D used in chronic kidney disease?
To treat and prevent secondary hyperparathyroidism and renal osteodystrophy.
Why is calcium gluconate used in severe hyperkalaemia?
In order to prevent life threatening arrhythmias. Other treatments such as insulin and glucose are given to actually lower the potassium concentration.
1) Calcium is essential for the normal functioning of what?
2) What is calcium homeostasis controlled by?
1) Muscle, nerves, bone and clotting.
2) PTH and vitamin D which increase serum calcium levels and bone mineralisation. Calcitonin which reduces serum calcium levels.
1) What happens in osteoporosis which increases the risk of fracture?
2) In CKD, what causes hyperphosphataemia and hypocalcaemia?
3) What then causes renal osteodystrophy in CKD?
1) There is a loss of bone mass.
2) Impaired phosphate excretion and reduced activation of vitamin D.
3) The electrolyte abnormalities stimulate secondary hyperparathyroidism which leads to a range of bone changes called renal osteodystrophy.
What may constitute treatment for renal osteodystrophy?
Oral calcium supplements to bind to phosphate in the gut and alfacalcidol to provide vitamin D that does not depend on renal activation.
Why is Calcium required in hyperkalaemia?
Because calcium raises the myocardial threshold potential which reduces excitability and therefore reduces the risk of arrhythmias.
1) What common adverse effects might oral calcium cause?
2) What might calcium gluconate administered intravenously too fast for hyperkalaemia cause?
3) What else might occur if IV calcium is given?
1) Dyspepsia and constipation.
2) Can cause cardiovascular collapse if administered too quickly.
3) Local tissue damage can occur if IV calcium is accidentally given into subcutaneous tissue.
1) When should calcium and vitamin D be avoided?
2) When administered IV, what must calcium not be allowed to mix with and why?
1) In cases of hypercalcaemia.
2) Sodium bicarbonate due to the risk of precipitation.
Name 4 drugs that oral calcium can reduce the absorption of.
1) Iron
2) Bisphosphonates
3) Tetracyclines
4) Levothyroxine
Name 3 symptoms of hypocalcaemia.
1) Paraesthesia
2) Tetany
3) Seizures
Below what level is hypocalcaemia considered to be severe?
<1.9 mmol/L
In severe hyperkalaemia, how should you prescribe calcium?
10mL calcium gluconate 10% for administration by slow IV injection. Repeat doses may be required if ECG changes persist.
1) Which foods might oral calcium preparations interact with?
2) How long should be left between ingesting calcium supplements and eating these foods?
3) How should calcium gluconate be administered?
1) Spinach, bananas and whole cereals.
2) About 2 hours.
3) By slow IV injection over 5-10 minutes into a large vein.
