Week 5 - Calcium and Renal stones Flashcards Preview

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Flashcards in Week 5 - Calcium and Renal stones Deck (18):
1

How much of the Ca in the kidney is reabsorbed? Where does this occur?

-95-98%
-65% paracellular in PCT
-25% in ascending LoH
-10% in DCT under PTH

2

What is the connection between kidney and vitamin D?

-The kidney hydroxylates 25-hydroxycholecalciferol to 1,25-dihydroxycholecalciferol (active vit D) via 1a-hydroxylase

3

What are the functions of active Vit D3?

-Increase bone resorption
-Increase Ca uptake from gut
-Increase resorption in kidneys

4

What controls hydroxylation of active vitamin D?

-PTH which is under negative feedback by Ca and Pi

5

What are the functions of PTH?

-Increase 1a-hydroxylase
-Aids bone remodelling by stimulating osteoclastic activity and slowly osteoblastic activity (to release cytokines to stimulate osteoclasts)
-Increases Ca resorption in kidney

6

What is the function of calcitonin?

-Decrease Ca resorption

7

How do Ca and Pi feedback on PTH?

-High levels of Ca or PTH bind to receptors on PT cells and inhibit/stimulate its release

8

What is the main cause of hyperparathyroidism? How does it cause hypercalcaemia?

-Parathyroid adenoma
-Excess PTH secretion causes continual Ca resorption despite plasma concetration

9

What are the symptoms of hypercalcaemia?

-Stones -> real calculi
-Moans -> Depression and cognitive difficulty
-Groans-> constipation

10

Name a malignancy why commonly causes hypercalcaemia

-Squamous cell carcinoma of lung due to secretion of PTHrp

11

How do you treat hypercalcaemia?

-Hydration and loop diuretics

12

What are the symptoms of hypocalcaemia?

-Hyperexcitability of NMJ leading to tetany
-Paralysis, coma, death

13

Where can renal stoned lodge?

-Anywhere along UT but most common at pelviuretic junction, pelvic brim or ureteric orifice

14

Who are renal stones more common in?

-Men

15

What are the main types of renal stone?

-Calcium
-Magnesium ammonium phosphate
-Uric acid

16

What are the most common causes of renal stones?

-Supersaturation of urine with solute -> low urine volume with hypercalcuria
-Formation of crystals in filtrate cause retention

17

What is the presentation of renal stones?

-Extreme colic

18

Which type of Ca is mainly filtered by the kidney?

-Ionised Ca