Vitamin D, Calcium And Stone Formation

Question 0

Describe how calcium levels in the plasma are regulated by hormones

Answer 0

PTH, active Vit. D –> bone (osteoclasts), intestine, kidney

Question 1

Describe the process which allows the kidneys to regulate calcium and phosphate

Answer 1

95-98% reabsorption of calcium
PTH control (intercalated cells of DCT) increases calcium
Reabsorption of Pi in PCT

Question 2

Describe the process that can lead to stone formation and the treatment

Answer 2

Process - dehydration (low fluid intake), high dietary intake of protein, sodium etc., metabolic condition e.g. hyperparathyroidism –> supersaturation
Type - calcium, magnesium, ammonium, phosphate, urate, cystine
Treatment - increased fluid intake, dietary changes

Question 3

Describe the process of Vit. D absorption and deficiency ranges

Answer 3

D2 (diet), D3 (sun) –> 24,25-(OH)2 D (inert form) -liver, kidney-> 1,25-(OH)2 D (active form)
Daily requirement - 800-1000 IU (adults)
Deficiency ranges:
Severe 50 nmol/L