CKD & renal failure

Question 1

What are homeostatic functions of the kidney?

Answer 1

• Electrolyte balance,
• acid-base balance
• volume homestasis
• EPO production
• 1-alpha hydroxylase for vitamin D
• excretes nitrogenous waste, hormones, peptides, middle sizes molecules, salt & water.
• Glucose metabolism: gluconeogenesis (filter/reabsorb glucose) & insulin clearance

Question 2

What does kidney failure lead to and why?

Answer 2

• Increased potassium & phosphate (not excreted),
• decreased bicarbonate so low pH (metabolic acidosis),
• salt & water imbalance
• low EPO so anaemia
• low calcium because low vitamin D, high PTH to compensate.
• Increased waste products: urea, creatinine.
• Insulin not cleared so insulin diabetics need less.
• Increased CV risk

Question 3

How might chronic and acute kidney failure present?

Answer 3

• Chronic may present with abnormal blood results but feel ok because body adapted.
• Acute may present worse (skin rash, haemoptysis etc)

Question 4

In case of kidney failure why metabolic acidosis? How will the body react to compensate for this?

Answer 4

• Less H+ ions excreted, less bicarbonate reabsorbed/produced so get metabolic acidosis.
• To compensate hyperventilation to get rid of CO2 (decrease)

Question 5

What happens to urea, creatinine, sodium, potassium and haemoglobin in kidney failure?

Answer 5

• Urea, creatinine increase.
• Sodium can increase or decrease.
• Potassium increases.
• Heamoglobin decreases

Question 6

Why anaemia in kidney failure?

Answer 6

less EPO production

Question 7

What can cause acute kidney failure? How can this present?

Answer 7

Eating wild mushrooms.

• Can present with nausea/vomiting/reduced urinary output.
• Waste products increased, sodium/potassium/hb stay kind of in range (because acute).
• Acidosis so PCO2 decreases to compensate

Question 8

What does kidney failure tend to do with salt and water?what does this elad to?

Answer 8

-Tend to get reduced secretion of salt & water (increased retention) leading to hypertension, oedema, pulmonary oedema.

Question 9

When is salt and water loss seen?

Answer 9

In tubulointerstisial disorders (damage to concentrating mechanism)

Question 10

Why do we get kidney failure acidosis and what can this cause?

Answer 10

• Reduced excretion of H+ ions, less bicarbonate so metabolic acidosis.
• Leads to anorexia & muscle catabolism.

Question 11

Why do we get hyperkalaemia in kidney failure? What can cause this?

Answer 11

Decreased distal tube potassium secretion. acidosis

Question 12

What are the symptoms associated with hyperkalaemia?

Answer 12

Cardiac arrhythmias, neural & muscular activity, vomiting to get rid of it

Question 13

What are the ECG changes seen in hyperkalameia?

Answer 13

Broad P wave (reduced amplitude, disappears), peaked T wave, QRS widening, heart block, asystole, VT/VF (can lead to irregular heartbeat)

Question 14

How does kidney failure cause hypocalcaemia? What is seen to compensate? What can this lead to?

Answer 14

Low vitamin D because of decreased 1-alpha hydroxylase activity, so leads to hypocalcaemia.
-to compensate hyperparathryoidism (inc PTH)

Question 15

What does chronic renal failure do to phosphate?

Answer 15

Phosphate retention (hyperphosphataemia). Can cause itch

Question 16

What do end-stage renal failure patients usually die from?

Answer 16

CV disease

Question 17

What causes CV risk?

Answer 17

Hypertension, diabetes, lipid abnormalities, inflammation, oxidative stress, mineral/bone metabolism disorders

Question 18

What is initial management for kidney failure? What do you do if they are hypovolaemic/hypervolaemic?

Answer 18

• If hypovolaemic - give fluids.

- If hypervolaemic - diuretics/dialysis trial

Question 19

What do you do to fix the hyperkalaemia?

Answer 19

1. To drive potassium into cell: sodium bicarbonate, insulin dextrose (caution).
2. To drive out of body - diuretics/dialysis.
3. To decrease gut absorption - potassium binders

Question 20

What to do for long term management of kidney failure?

Answer 20

EPO injections for anaemia, diuretics for salt/fluid overload, phosphate binders, 1,25 Vit D supplements, symptom management.

• Home therapy: haemodialysis, peritoneal dialysis/assisted programmes.
• In centre therapy: haemodialysis 4 hours 3x a week for transplantation

Question 21

What do you need to avoid in transplantable patients with kidney disease and why?

Answer 21

Transfusions.

Prevent sensitisation to prevent transplant failure

Question 22

What kidney size in chronic kidney failure? What kidney size in acute kidney failure?

Answer 22

Chronic - small kidneys.

Acute - normal sized kidneys

Question 23

What are traditional methods of assessing GFR and their disadvantages?

Answer 23

1. urea: poor indicator confounded by diet, catabolic state, GI bleeding, drugs, liver function.
2. creatinine: affected by muscle mass, age, race, sex.
3. radionuclide studies - eg. EDTA clearance, reliable but expensive.
4. creatinine clearance: hard for elderly to collect accurate sample, overestimates GFR at low GFR (small amount creatinine secreted into urine)
5. insulin clearance: laborious, for research purposes only

Question 24

When cant we see a trend for creatinine?

Answer 24

CKD-EPI . when EGFR above 90 cant see trend

Question 25

What does NICE classification classify as kidney failure? What does it look at?

Answer 25

Looks at albumin creatinine ration ACR for proteinuria & GFR.
ACR <3 normal. 3-30 moderate increased. >30 very increased.
GFR >90 normal and high. <15 kidney failure