Session 5 - Kalcium and the Cidney (intentional, promise) Flashcards Preview

Semester 3 - Urinary > Session 5 - Kalcium and the Cidney (intentional, promise) > Flashcards

Flashcards in Session 5 - Kalcium and the Cidney (intentional, promise) Deck (48)
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1
Q

Give five functions of Calcium

A
  • Muscle contraction
    • Inactivation/activation of enzymes
    • Nerve conduction
    • Exocytosis
    • Hormone secretion
    • Haemostasis
2
Q

What is the physiologically active from of Ca2+?

A

• Ionised form

3
Q

Give the three forms in which Ca2+ is found in the body

A
  • Free ionised species
    • Protein bound
    • Complexed
4
Q

How much of dietary calcium is absorbed?

A

• 20-40% is absorbed (25mmol)

5
Q

When does calcium absorption increase? (3)

A
  • Growing children
    • Pregnancy
    • Lactation
6
Q

How much calcium do the kidney filter per day?

A

• 250mmol

7
Q

How much of the body’s calcium reservoir is found in the ECF?

A

• 1%

8
Q

What chemical is responsible for the absorption of calcium from the gut?

A

• 1,25 - OH 2D control

9
Q

Where is the majority of calcium reabsorption in the kidney?

A
  • 65% reabsorbed in proximal tubule
    • 20-25% recovered in ascending loop of henle
    • 10% recovered in DCT under control of PTH
10
Q

What is the standard 24hr urinary calcium excretion?

A

• <10 mmol

11
Q

How much calcium filtered by kidney per day?

A

250 mmol

12
Q

Give the actions of PTH

A
  • Increases reabsorption in kidney
    • Increases breakdown of bone

Converts calciferol to calcitriol in kidney

13
Q

What is the inactive form of Calcitriol called?

A

Calciferol

14
Q

What are the actions of calcitriol?

A
  • Increase breakdown of bone
    • Increase reabsorption in kidney

Increase absorption of calcium from gut

15
Q

How is vitamin d2 produced?

A

• By gut

16
Q

How is vitamin d3 produced?

A

• By skin

17
Q

How does vitamin D become calciferol?

A

• Hydroxylation in the liver

18
Q

When does calciferol become calcitriol?

A

• After 2nd hydroxylation

19
Q

How is Calcium release regulated?

A
  • Negative feed back to parathyroid gland
    • Gq receptor inhibit PTH release
    • Reduce further calcium absorption
20
Q

What are the three major causes of hypercalcaemia?

A
  • Primary hyperparathyroidism
    • Haemtological malignancies
    • Non-haematological malignancies
21
Q

How do malignancies cause hypercalcaemia?

A
  • PTHrp released

* Does not convert calciferol to calcitriol

22
Q

Give four systems that hypercalcaemia causes symptoms in

A
  • Gastrointestinal
    • Cardiovascular
    • Renal
    • CNS
23
Q

Give four gastrointestinal symptoms of hypercalcaemia

A
  • Anorexia
    • Nausea/Vomiting
    • Constipation
24
Q

Give three cardiovascular consequences of hypercalcaemia

A
  • HypertensionShortened QT

* Enhanced sensitivity to digoxin

25
Q

Give three renal consequences of hypercalcaemia

A
  • Polyuria
    • Polydipsia
    • Nephrocalcinosis
26
Q

Give three cognitive effects of hypercalcaemia on the CNS

A
  • Cognitive difficulties
    • Apathy
    • depression
27
Q

Outline treatments for hypercalcaemia

A

General measures
• Hydration - Increase Ca2+ excretion
• Loop diuretics - Increase Ca2+ excretion
Specific measures
• Bisphosphonates - Inhibit breakdown of bone
• Calcitonin - Opposes the action of PTH
Treat underlying condition

28
Q

What percentage of people will develop kidney stones in their life?

A
  • 20% mean

* 5-10% of women

29
Q

What is the most common form of kidney stone?

A

• 70-80% made of calcium

30
Q

What factors are involved in the formation of kidney stones?

A
  • Low urine volume
    • Hypercalcuria

Low urin pH

31
Q

What does the mechanism of stone formation involve?

A

• Super-saturation of urine with calcium oxalate

32
Q

What does conservative management of kidney stones involve?

A
  • Increasing fluid intake
    • Restricting dieatary oxalate and sodium
    • Restrict calcium and animal protein
33
Q

What calcium conc do we want to measure in the blood?

A

• Ionised calcium

34
Q

What are the problems with measuring ionised calcium?

A

Degrades quickly

35
Q

What hormone is responsible for calcium absorption from the gut?

A

Calcitriol (a derivative of vitamin D)

36
Q

How is excess vitamin D stored?

A

• Converted to 24,25 - (OH)2 vitamin D

Inert

37
Q

Why do people with HIV get vitamin D deficiency?

A

• Anti-retroviral treatment induces liver enzymes to break down vitamin D

38
Q

Where is calcium reabsorbed in the most part?

A
  • PCT - 65%

* TAL - 25%

39
Q

What three things regulate calcium reabsorption in the kidney?

A
  • PTH
    • Vitamin D
    • Plasma Ca2+ levels
40
Q

What can be used to treat hypercalcaemia that acts on the kidney?

A

• Loop diuretics which inhibit Ca2+ reabsorption

41
Q

Whyshould thiazide not be used in hypercalcaemia?

A

• Increases Ca2+ reabsorptio in kidney

42
Q

What percent of men get renal stones?

A

• 20%

43
Q

What is the main type of renal stone?

A

• Calcium

44
Q

Give three types of renal stone other than calcium

A
  • Magnesium Ammonium Phosphate
    • Urate
    • Cystine
45
Q

What is gout?

A
  • Too much alcohol
    • Alcohol competes with urate in kidney
    • Urate accumulated in tissues
46
Q

Give five promoters of kidney stone formation?

A
  • Urine supersaturation with calcium oxalate
    • Low ionic strength
    • Low citrate
    • Magnesium
    • Low pH
47
Q

What is nephrolithiasis?

A

• Calculi in the kidney

48
Q

What is the classic presentation of kidney stones?

A
  • Loin to groin pain
    • Renal colic
    • Hydronephrosis