Calcium Vitamin D and Phosphate

Question 1

What is the trigger for release of PTH?

Answer 1

Low calcium

Question 2

What is the action of PTH?

Answer 2

Increase bone resorption, increases conversion to 1,25 vitamin D to increase calcium absorption, inhibits phosphate reabsorption in the kidney, increases calcium reabsorption in the kidney

Question 3

What is the most common cause of primary hyperparathyroidism?

Answer 3

Solitary adenoma

Question 4

What are the differential diagnoses for primary hyperparathyroidism?

Answer 4

Multiple adenomas, hyperplasia and familial hypocalciuric hypercalcaemia

Question 5

What is familial hypocalciuric hypercalcaemia?

Answer 5

A mutation in calcium sensing receptor which means that parathyroid cells are insensitive to inhibition by calcium

Question 6

What are the indications for surgery in primary hyperparathyroidism?

Answer 6

Calcium > 2.8
BMD T < - 2.5
Age < 50
eGRR < 60
24 hour urine calcium > 10mmol/24 hours

Question 7

What are the effects of severe hypophosphataemia?

Answer 7

Bone mineralisation defects
Reduced conscious state
Impaired cardiac and skeletal muscle function

Question 8

What are the causes of hypophosphataemia?

Answer 8

Refeeding syndrome
Treated ketoacidosis
Sepsis
Hungry bone syndrome
Repiratory alkalosis
Eating disorders
Alcoholism
Antacids
Severe vitamin D deficiency
Diarrhoea/malabsorption
Renal phosphate wasting

Question 9

What are the congenital causes of renal phosphate wasting?

Answer 9

PHEX
FGF23
Vitamin D receptor mutation

Question 10

What are the acquired causes of renal phosphate wasting?

Answer 10

Hyperaparathyroid syndrome
Fanconi syndrome
Volume expansion
Vitamin D deficiency
Thiazide diuretics
Oncogenic osteomalacia