General - Phosphate

Question 1

Hyperphosphatemia is a serum phosphate level of higher than what?

Answer 1

> 4.5mg/dL

Question 2

1) What is the commonest cause of hyperphosphatemia?
2) Name 3 other causes

Answer 2

1) Renal failure
2) Excessive phosphate load (excessive use of phosphate containing laxatives or enemas, vitamin D intoxication, tumour lysis syndrome), increased renal absorption (hypoparathyroidism, acromegaly, thyrotoxicosis) and transcellular shifts (lactic acidosis, diabetic ketoacidosis)

Question 3

What effect does high phosphate have on calcium?

Answer 3

Causes hypocalcemia because phosphate in the blood combines with calcium

Question 4

1) Hyperphosphatemia can be managed with a calcium based phosphate binder - name one of these
2) Name a non-calcium based phosphate binder

Answer 4

1) Calcium acetate, calcium carbonate
2) Lanthanum, sevelamer

Question 5

Hypophosphatemia is when there’s a serum phosphate level of lower than what?

Answer 5

<2.5mg/dL

Question 6

Name 3 causes of hypophosphatemia

Answer 6

• Redistribution into cells (refeeding syndrome, respiratory alkalosis, insulin, hungry bone syndrome)
• Increased renal loss (hyperparathyroidism, impaired Vitamin D metabolism, renal tubular disorders e.g. Fanconi’s syndrome)
• Reduced gut uptake (malnutrition, vitamin D deficiency, chronic diarrhoea, chronic malabsorption)