Session 5 - Kidney, calcium and renal stones Flashcards

1
Q

What is the function of calcitriol?

A

Calcitriol increases Ca levels in blood by promoting absorption of Ca from intestine and reducing loss of calcium in kidneys.

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2
Q

outline the process which occurs if serum calcium is low.

A
  • Parathyroid gland secretes PTH
  • PTH pulls calcium and phosphate from bones and into blood and tells kidneys to produce calcitriol from calcifediol (25-(OH) vit D).

PTH also increases calcium and magnesium reabsorption in the kidneys and decreases phosphate and bicarbonate reabsorption.

Low Ca –> PTH –> Calcifediol –> calcitriol

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3
Q

Give 3 factors that can lead to stone formation

A
  • Low urine pH
  • Saturated levels of calcium oxalate in the urine
  • Inadequate fluid intake or excessive fluid loss
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4
Q

Describe the pathophysiology behind kidney stones

A
  • Urine becomes supersaturated (urine contains more solutes than it can hold in solution) with calculogenic substances
  • Through the process of nucleation, a crystal forms by adhering to a wall, and the seed crystal grows
  • Unusually high or low pH affects the solubility of certain ions in urine, making it more or less likely to form a crystal.
  • Normal urine contains chelating agents, e.g. citrate, that inhibit nucleation of crystals. Low levels of chelating agents = higher risk of renal stoness
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5
Q
A
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