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214.201 > Renal Failure > Flashcards

Renal Failure Flashcards

1
Q

What are the 5 major functions?

A
  • Removal of water and wastes from the blood
  • Maintains electrolyte balance
  • Maintains acid-base balance
  • Regulates blood pressure by renin secretion
  • Stimulates production of red blood cells by erythropoietin secretion
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2
Q

What is the GFR?

A
  • The glomerular hydrostatic (blood) pressure is the major factor forcing fluids out of the blood
  • This pressure has to overcome the colloid osmotic pressure and the capsular hydrostatic pressure
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3
Q

What are factors determining GFR?

A
  1. Total surface area available for filtration (number of nephrons)
  2. Filtration membrane permeability
  3. Net filtration pressure (glomerular blood hydrostatic pressure minus the combined pressure of the osmotic and capsular hydrostatic pressure)
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4
Q

What changes affect GFR?

A
  • Blood flow

- Blood pressure

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5
Q

How does hypertension affect GFR?

A
  • Hypertension may impair blood flow to the kidney by causing hypertrophy of the smooth muscles in the afferent arterioles reducing the lumen and therefore the blood flow
  • Hypertension can also cause damage to the endothelium that accelerates the progress of atherosclerosis, which can decrease lumen of the blood vessels and therefore decrease blood supply to kidneys
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6
Q

How much cardiac output do the kidney receive?

A

20-25% of the cardiac output to provide enough plasma for high rates of glomerular filtration needed for regulation of body fluid volumes

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7
Q

What can decreased renal blood flow cause?

A
  • Oliguria <300-500mls a day
  • Anuria <50 mls a day
  • Decreases the work of the kidney and therefore also O2 requirements of cells (Blood flow below 20% of normal does not meet O2 requirements at rest and renal cells die)
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8
Q

What is renal failure?

A

A decrease or cessation of glomerular filtration

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9
Q

What is chronic kidney disease?

A

A progressive and irreversible decline in glomerular filtration rate

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10
Q

What is acute kidney disease?

A

An abrupt decrease or cessation of glomerular filtration rate or kidneys stop working - which is reversible if the patient gets correct and prompt treatment

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11
Q

What are causes of acute kidney injury?

A
  • Complications of surgery, severe burns, trauma
  • Renal ischaemia caused by blood clots, hypovolemia
  • Drugs (antibiotics-gentamycin, streptomycin, NSAID- aspirin, ibuprofen)
  • Toxins (heavy metals, alcohol)
  • Heatstroke
  • Multiple organ failure
  • Sepsis
  • Obstructed urine flow
  • Acute pyelonephritis
  • Kidney stones
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12
Q

What are the causes of kidney disease (3 groups)?

A
  • Pre-renal: mostly associated with lack of blood supply/ low BP
  • Renal: affecting the nephrons directly
  • Post-renal: mostly due to back pressure due to obstructions
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13
Q

What are the phases of acute kidney injury?

A

1) Oliguric - decreased urine output (severe deficiency is anuria)
2) Diuretic - filtration is increased but absorption is impaired
3) Recovery - gradual return to normal functioning

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14
Q

What are the causes of chronic kidney disease (CKD) (Renal failure) (3 groups) ?

A

1) Pre-renal: shock, ischaemia
2) Renal: direct damage to nephrons due to infection,
nephrotoxic injury
3) Post-renal: increased hydrostatic pressure in Bowmans capsule, slowing filtration due to the obstruction of ureters

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15
Q

What are causes of chronic kidney disease?

A
  • Diabetes
  • Hypertension
  • Obstructive nephropathy (caused by kidney stones, prostate tumour)
  • Kidney disease (chronic glomerulonephritis, pyelonephritis, polycystic kidney disease)
  • Renal artery stenosis
  • Lead poisoning
  • Fatty plaque deposits -atherosclerosis in kidney artery
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16
Q

What are some examples of urinary tract obstructions?

A
  • Urethral stricture
  • Foreign body (stone)
  • Benign prostatic hyperplasia
  • Urethral stricture
17
Q

What are the stages of chronic kidney disease?

A

1) Diminished renal flow
- No signs or symptoms
2) Renal insufficiency
- Waste products build up
- Inability to concentrate or dilute urine
- 75% or more nephrons are lost
3) End stage
- Oliguria present
- Waste products build up
- Treatment required
- 90% or more nephrons are lost
Issue: lack of biochemical markers to identify developing renal failure

18
Q

What are some renal function tests?

A
  • GFR
  • Creatinine clearance rate (Ccr or CrCl)
  • Blood urea nitrogen
19
Q

What is GFR and the equation?

A
  • The volume of fluid filtered through the glomerular capillaries into the Bowman’s capsule per unit time
    Equation: (urine concentration x urine flow) / plasma concentration
  • Usually estimated from creatinine clearance
20
Q

What is the creatinine clearance rate?

A
  • The volume of blood plasma that is cleared of creatinine per unit time
  • Creatinine clearance or estimates of creatinine clearance based on the circulating creatinine level are used to measure GFR
  • Creatinine is the broken-down product of creatine phosphate in muscle, and is usually produced at a fairly constant rate by the body
21
Q

What is the normal range for GFR?

A

100-130 ml/min/1.73m2

22
Q

What do blood urea nitrogen and creatinine indicate?

A

Raised levels indicated 60% of kidney function is lost

23
Q

What is the equation for creatinine clearance?

A

Cockcroft-Gault formula:

eCCr = [(140 – Age) x Mass (kg) x Constant in ml/min] / Serum creatinine (in umol/L)

24
Q

What is treatment for renal failure?

A
  • Continuous ambulatory peritoneal dialysis (CAPD)
  • Haemodialysis
  • Renal transplant
25
Q

What is CAPD?

A

Cleaning of the peritoneal cavity to remove wastes from the body

26
Q

What is needed for a kidney transplant?

A
  • Suitable donor matching tissue and blood group
  • Third (donated) kidney is transplanted into the abdominal cavity
  • Regular check for rejection and function
  • Immunosuppressive medication (prednisone & cyclosporine)
27
Q

What is haemodialysis?

A

Removal of wastes via fistula in the arm which process blood through dialysis machine

28
Q

What are the diet interventions when on dialysis?

A
  • Decreased fluid intake- replace insensible loss only
  • Decreased sodium
  • Decreased potassium
  • Decreased protein
  • Adequate carbohydrate/ calorie intake
29
Q

How does salt build up affect the body?

A
  • Increase BP

- Increase thirst

30
Q

How does potassium build up affect the body?

A
  • Bad for the heart

- In extreme cases may stop the heart

31
Q

How does phosphate build up affect the body?

A
  • Can cause itching
  • Long-term, can damage blood vessels
  • Works with calcium
32
Q

How does lack of protein affect the body?

A
  • Fluid retention

- Low immunity

33
Q

How does lack of iron affect the body?

A
  • Anaemia
34
Q

How do phosphate and calcium interact in renal failure?

A

1) Phosphate builds up and binds to calcium, lowering calcium levels
2) Kidney can not produce the active form of vitamin D causing less calcium absorption from the gut
3) High urea levels suppress vitamin D absorption in the gut
4) Low calcium levels cause parathyroid levels to increase, calcium released from bones leading to osteoporosis
- Vitamin D should be administered to prevent this

35
Q

What are hypocalcemia causes and signs?

A
  • Increased capillary permeability
  • Neuromuscular excitability
  • Decreases blood coagulation
  • If severe, tetany can result
    1) Chvostek’s sign- contraction of facial muscle in response to light tap on facial nerve
    2) Trousseau’s sign- carpal spasm induced by inflating a blood pressure cuff
36
Q

How does anaemia develop?

A
  • Anaemia can develop due to low erythropoietin (EPO) levels, & deficiencies in iron & folate (treatment with each of these can be effective)
  • Platelet abnormalities which may lead to bleeding (and in turn aggravate anaemia)
37
Q

What are other consequences of renal failure?

A
  • Increased uric acid may lead to kidney stones or gout
  • Metabolic acidosis may develop (less excretion of H+)
  • Nausea, vomiting, fatigue and neuropathy due to uremia and electrolyte imbalances
  • Infertility due to decreased hormone levels and neuropathy
  • Yellow-gray skin due to absorption of urinary pigments, dry skin due to decreased oil and sweat gland activity, pruritis due to calcium-phosphate deposition in the skin
  • Hypertension and heart failure due to fluid overload

214.201 (17 decks)

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