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Flashcards in Physiology 4 Deck (54):
1

What is acute renal failure?

Occurring suddenly eg one or several days.
Stop urinating for a period of 24 hours

2

Is ARF reversible?

ARF is often reversible The longer it lasts…less likely is recovery

3

What is consistent about chronic renal failure?

It always has the same specific gravity of plasma

4

What is CRF?

A reduction in GFR - it is considered significant it is less than 50ml/min =

5

Is the degree of tubular impairment fixed or rlative?

The degree of tubular impairment relative to filtration impairment is highly variable…… from “glomerular” disease to “tubular” disease

6

what happens when there is a loss of GFR?

Loss of GFR is invariably accompanied by impairment in tubular processes; reabsorption and secretion

7

What are the most important endocrine dysfunction which occurs in renal failure?

RAS
Vit D
Erythropoeitin

8

Is urea a good guide to GFR?

No its a poor guide

9

How much urea is absorbed?

50% - variable

10

Where does urea come from?

Protein

11

When are urea levels up?

Elevated in numerous situations other than CRF! Eg catabolic states, steroid Rx

12

When are urea levels down?

Malnutrition
Liver disease

13

How is GFR measured?

Creatinine Clearance = UV/P = GFR

14

Why is creatinine used as a measure of GFR?

1 Creatinine production is constant
2 Filtered, but 15% bound to plasma proteins (underestimates GFR)
3 Not reabsorbed
4 Small amount of secretion (overestimates GFR)
5 (2) and (4) tend to cancel out

15

What are the normal creatinine levels?

50-120 µM/L

16

Why is a baseline creatinine important?

It should stay the same, if it rises then GFR is falling

17

What happens when nephrons are destroyed?

The remaining nephrons tend to filter more. This tends to worsen the failure (i.e. it puts more pressure on the remaining nephrons)

18

What are the types of acute renal failure?

•Pre-renal
•Renal
•Post-renal

19

What causes pre-renal ARF?

If the MAP drops far enough the GFR will drop and urine output will be insufficient.

20

What is olguria?

Is the low output of urine

21

What is anuria?

No urine output

22

What is rhabdomyolysis?

Leads to leakage of enough products into the urine which were not present

23

What are the specific causes of pre-renal ARF?

Shock
Sepsis
Haemolysis Rhabdomyolysis
Nephrotoxic drugs

24

What is the most common nephrotoxic drug?

Gentomycin

25

What is acute tubular nephritis?

ARF not due to volume depletion

26

What Intrinsic acute renal failure

Glomerular disease
Interstitial nephritis (Tubulo-interstitial)
Tubular damage

27

What are the specific causes of tubular damage?

Ischemia
Toxins

28

What are the specific causes of interstitial nephritis?

Inflammatory reaction, often drug-related

29

What is the most common cause of ARF?

Acute tubular necrosis

30

What is the major concern of someone with Acute tubular necrosis?

acidosis and ↑K+

31

What is post-renal acute renal failure?

Outlet Obstruction
– Ureteric, cystic or urethral
– stones, clots, fibrosis, tumors

32

What is chronic renal failure?

Irreversible loss of renal function • Reduction in functional renal mass • Develops over months to years (highly variable rates of decline)

33

What is another name for chronic renal failure?

uraemia

34

What happens to nephrons in CRF?

Remaining nephrons hypertrophy

Glomerular hyperfiltration
– loss of functional reserve
– glomerular hypertension
– further damage and glomerulosclerosis

35

What happens to the fluid in CRF?

The leaves the nephron largely unchanged

36

What can happen to people with CRF?

Are susceptible to both dehydration and hypertension if their water and salt intake adjusts

37

What are the symptoms of uremia?

– Fatigue
– Loss of appetite
– Skin pigmentation (lemon)

38

What causes skin pigmentation?

Crystallisation of urea on the skin surface

39

What are the causes of CRF?

• Diabetes
• High blood pressure
• Chronic glomerulonephritis
• Cystic disease (poly-cystic kidney disease)

40

What is uremia?

Accumulation of “uremic” toxins
• Mostly urea

41

When is uremia symptomatic?

Symptomatic with less than 30% of normal renal function

42

What are the salt and water imbalances observed in CRF predominantly of the glomerulus?

Sodium retention and hypertension

43

What are the salt and water imbalances observed in CRF predominantly of the tubules?

– Sodium wasting and low BP
– Impaired concentrating ability & polyuria

44

What happens to K in CRF?

Tends to rise, esp late-stage (not as fast as ARF)
– Higher in diabetes

45

What happens to pH in CRF?

falls i.e. H+ accumulates; failure to excrete non-volatile acids • Produced at high rate in normal metabolism • Excretion requires high GFR • reduced ammonia production • low [HCO3-]

46

What happens to phosphate when GFR falls?

Reduced phosphate excretion
Tubular capacity to reabsorb stays the same concentration secreted reduced which results in a slow rise in [PO4]
Reciprocal reduction in [Ca]

47

How is phosphate excreted?

Sodium and Phosphate co-transporter

48

What does [PO4] signal?

Parathyroid ---

49

What happens when there is low vit D?

Reduced renal mass and Vit D activation
– Hyperphosphatemia
– Renal “rickets”: osteomalacia with fractures and subperiosteal resorption

50

What causes secondary hyperparathyriodism?

Excessive secretion of parathyroid hormone (PTH) by the parathyroid glands in response to hypocalcemia

51

What affect does 2nd degree have on bone?

hyperparathyroidis (excessive osteoclastic activity)

52

What is osteomalacia?

Osteomalacia refers to a softening of your bones, often caused by a vitamin D deficiency

53

What are the symptoms of uremia?

Fatigue
Loss of appetite
Skin pigmentation (lemon)

54

What are some common causes of CRF?

• Diabetes
• High blood pressure
• Chronic glomerulonephritis
• Cystic disease