CHRONIC KIDNEY DISEASE AND RENAL FAILURE

Question 1

List homeostatic functions of the kidneys

Answer 1

Electrolyte balance
Acid-base balance
Volume homeostasis

Question 2

List endocrine functions of the kidneys

Answer 2

Erythropoietin

1 alpha-hydroxylase vitamin D

Question 3

List excretory functions of the kidneys

Answer 3

Nitrogenous waste
Hormones
Peptides
Middle sized molecules
Salt and water

Question 4

List glucose functions of the kidneys

Answer 4

Gluconeogenesis

Insulin clearance

Question 5

What occurs in kidney failure?

Answer 5

Homeostatic function failure:

• increased potassium
• decreased bicarbonate
• decreased pH
• increased phosphate
• salt and water imbalance

Endocrine function failure:

• hypocalciaemia (decreased 1-25 Vit D)
• anaemia (reduced EPO)
• increased parathyroid hormone (decreased 1-25 Vit D)

Excretory function failure:

• increased urea
• increased creatinine
• decreased insulin requirement

Increased cardiovascular risk

Question 6

How does a chronic kidney failure present compared to an acute kidney failure?

Answer 6

In chronic, patient might not feel as bad as they’re bodies have had time to adapt to the effects. Small, shrunken kidneys

In acute, the presentation is sudden and obvious. Normal sized kidneys

Underlying causes of the kidney failure will also have their own presentations

Question 7

How can chronic kidney failure present on examination?

Answer 7

Pale
Cold hands
Capillary refill decreased
Tachypnea/Dyspnea
Lethargy, weakness and anorexia
Hypotension due to hypovolemia
Oedema

Question 8

Why might a patient with kidney failure be tachypnoeic/ have kussmaul respiration?

Answer 8

Tachypnea indicates metabolic acidosis. This is because patients with kidney failure will have reduced excretion of H+ leading to increased H+ in blood and they don’t have enough HCO3- to neutralise it. Therefore the body tries to reduce H+ by decreasing CO2 via increased respiration rate

Decreasing CO2 forces this equation left to reduce H+
CO2 + H2O –> HCO3- + H+

Question 9

Will patients with respiratory acidosis have high or low CO2?

Answer 9

High since they aren’t ventilating well which forces the equation right

CO2 + H2O –>

Question 10

How can acute kidney failure/injury (AKI) present on examination?

Answer 10

Low respiration rate - bradypnoeic
Oedema
Feeling sick or being sick
Diarrhoea
Dehydration
Peeing less than usual
Confusion
Drowsiness

Question 11

Why might hypertension, oedema and pulmonary oedema occur in a patient with kidney failure?

Why might this not happen?

Answer 11

Reduction in salt and water secretion

Salt and water loss maybe seen in tubulointerstitial disorders - damage to concentrating mechanism
Hypovolemia may be the cause of AKI

Question 12

What does hyponatremia mean?

Answer 12

Sodium level IN BLOOD below normal

Doesn’t necessarily mean reduced total body sodium

Question 13

How does acidosis from kidney failure cause hyperkalaemia?

Answer 13

Increase in H+ means more H+ influx into cells which forces the intracellular K+ out.

Question 14

What does acidosis eventually cause?

Answer 14

Anorexia

Muscle catabolism

Question 15

What are the causes of hyperkalaemia in kidney failure?

Answer 15

Decreased distal tubule potassium secretion

Acidosis

Question 16

What are the symptoms of in hyperkalaemia?

Answer 16

Cardiac arrhythmias
Neural and muscular activity
Vomiting - to get rid of potassium

Endocrine: helps drive

• Low levels of 1-25 Vit D
• Hypocalcaemia
• Hyperparathyroidism

Question 17

What ECG changes can be seen in a patient with hyperkalaemia?

Answer 17

Peaked T waves
P wave - broadens/reduced amplitude/absent
QRS widening

Heart block
Asystole
VT/VF

Question 18

Why is cardiovascular risk important to consider in CKD?

Answer 18

Patient with CKD is more likely to die from cardiovascular disease than end stage renal failure

Question 19

List the risks of cardiovascular disease

Answer 19

Hypertension
Diabetes
Lipid abnormalities
Inflammation
Oxidative stress
Mineral/bond metabolism disorder

Question 20

What is the initial management for a patient with kidney failure?

Answer 20

Fluid balance:

• hypovolaemic - give fluids
• hypervolaemic - diuretics/dialysis if not peeing

Hyperkalaemia:

• Sodium bicarbonate (drive into cells)
• Insulin dextrose (drive into cells)
• Diuretics/dialysis (drive out of body)
• Potassium binders (stops gut absorption)

Question 21

Why must you be careful when giving insulin dextrose and at what potassium level can you give it?

Answer 21

Risk of fatality due to hypoglycaemia

Only if potassium > 6.5

Question 22

What is the long term management for a patient with kidney failure?

Answer 22

Conservative treatment:

• EPO injections
• Diuretics
• Phosphate binders
• 1-25 vit d supplements
• Symptom management

Home therapy:

• Haemodialysis
• Peritoneal dialysis

In centre therapy:
- Haemodialysis (4 hours, 3 times a week)

Transplantation

Question 23

What should transplantable patients with kidney disease avoid?

Answer 23

Transfusions -> sensitisation -> transplant failure

IV lines to antecubital/cephalic veins as it may cause scarring so you can’t do a fistula

Question 24

What are the methods for assessing GFR and each of their limits?

Answer 24

Urea
- poor indicator as confounded by diet/drugs…

Creatinine

• affected by muscle mass, age, race, sex…
• consider the patient when interpreting result

Creatinine clearance

• Difficult for elderly to collect accurate samples
• Overestimates GFR at low GFR

Insulin clearance
- Laborious (research purposes only)

Radionuclide studies

• Reliable but expensive
• EDTA clearance etc

Question 25

How can you classify risk of adverse outcomes in kidney failure?

Answer 25

NICE guidance classification
- GFR AND ACR (albumin:creatine ratio) categories

As they increase so does risk of adverse outcomes