CKD and Renal replacement therapy

Question 1

Define CKD. (2)

Answer 1

Kidney damage of GFR < 60ml/min/1.73m2 for 3 months.

Kidney damage is define as pathologic abnormalities or markers of damage including abnormalities in blood, urine tests or imaging studies. e.g. haematuria or proteinuria

Question 2

What are the stages of CKD? (5)

Answer 2

1: GFR >90
2: GFR 60-89
3: GFR 30-59
4: GFR 15-29
5: GFR <15

Question 3

Name 4 causes of CKD. (4)

Answer 3

• Vascular: hypertension**, renal artery stenosis, vasculitis
• Glomerular: diabetes**, GN, amyloidosis, SLE
• Tubulointerstitial: nephrocalcinosis, pyelonephritis, TB
• Obstruction and others: myeloma, HIV, scleroderma, gout, renal tumour
• Congenital: Polycystic kidney disease, Alport’s syndrome, tuberous sclerosis

Question 4

Name 2 reasons for the anaemia seen in patients with CKD. (2)

Answer 4

Reduced EPO production
Shortened red cell survival
Increased blood loss (due to haemolysis)
Dietary deficiency of iron and folate

Question 5

What is renal osteodystrophy? (3)

Answer 5

Term for the various forms of bone disease that develop in CKD i.e. osteomalacia, osteoporosis, secondary and tertiary hyperparathyroidism, osteosclerosis.

[renal phosphate retentio and failure to hydroxylate vitamin D lead to a fall in serum calcium levels and production of PTH. Sustained PTH secretion leads to skeletal decalcification]

Question 6

What neurological complication can occur in a patient suffering with CKD? (2)

Answer 6

Polyneuropathy as peripheral parasthesia and weakness
Autonomic dysfunction as postural hypotension and disturbed GI motility.
Advanced uraemia causes confusion, myoclonic twitches and fits.
Carpal tunnel syndrome occurs by beta2-microglobulin related amyloidosis (complication of dialysis)

Question 7

What is the highest cause of mortality in CKD patients? (3)

Answer 7

Cardiovascular disease particularly from MI, HF, sudden cardiac death and stroke.

Due to increased frequency of hypertension, dyslipidaemia and vascular calcification.
Renal disease also causes a form of cardiomyopathy with both systolic and diastolic dysfunction.
Pericarditis and pericardial effusion can occur in severe uraemia.

Question 8

Name 3 findings on examination and investigations that would suggest CKD over AKI? (3)

Answer 8

Small kidneys on ultrasound
Normochromic anaemia
Renal osteodystrophy

Question 9

What is the management of CKD? (3)

Answer 9

Treat underlying cause: e.g. diabetes

Manage complications:

• anaemia: correct abnormalities. EPO monthly
• bp control: ACEi
• hypocalcaemia: alfacalcidol, bisphosphonates
• diet: high energy, restriction of potassium, restriction of protein and phosphate intake
• drugs: avoid nephrotoxic drugs e.g. NSAIDs and alter dosages for renal disease
• oedema: diuretics
• cardiovascular risk: smoking cessation, statin, etc
• infections: flu and pneumococcal vaccine

Renal replacement therapy

Question 10

Name 3 types of renal replacement therapy. (3)

Answer 10

Peritoneal dialysis
Haemodialysis
Renal transplant

Question 11

What is the basis of dialysis? (2)

What is the semi-permeable membrane in the 2 types of dialysis? (2)

Answer 11

Uraemic toxins are efficiently removed from the blood by the process of diffusion across a semipermeable membrane towards the low concentrations present in the dialysis fluid.

Haemodialysis: blood is in extra-corproeal circulation and expose to dialysis fluid through artificial semi-permeable membrane.
Peritoneal: Dialysis fluid is instilled into the peritoneal cavity and the peritoneum acts as the semi-permeable membrane.

Question 12

What is the purpose of an AV fistula? (2)

Answer 12

Adequate haemodialysis requires a blood flow of at least 200ml/min and the most reliable way of achieving this is by surgical construction of an artery-venous fistula usually in the forearm.
This is a permanent and accessible site for the insertion of needles.

Question 13

How often does haemodialysis need to be performed in an average adult? (1)

Name 2 complications. (2)

Answer 13

4-5 hours of haemodialysis 3 times a week.

Hypotension: partly due to excessive removal of extracellular fluid.
Clotting: contact of blood with foreign surfaces starts clotting cascade, all patients treated with heparin prophylactically.

Question 14

Describe peritoneal dialysis. (3)

Answer 14

A permanent tube (Tenkoff catheter) is placed in peritoneal cavity via a s/c tunnel.
Bags of dialyse are connected to catheter and the fluid run in. The urea, creatinine, phosphate and toxins pass into dialyse and is collected.
In continuous ambulatory peritoneal dialysis this is exchanged 3-5 times per day.

Question 15

What is the main complication of peritoneal dialysis? (1)

Answer 15

Bacterial peritonitis often with staphylococcus epidermidis.

Question 16

What are the 2 leading causes of death in long term dialysis patients? (2)

Answer 16

Cardiovascular disease (due to atheroma)
Sepsis

Question 17

Name 3 complications of long term haemodialysis? (3)

Answer 17

Cardiovascular disease
Sepsis (staph aureus)
Amyloidosis (results in carpal tunnel and joint pains)
Aluminium toxicity

Question 18

What is the most effective form of renal replacement therapy? (1)

Answer 18

Renal transplant

Question 19

What is the most common form of renal transplant? (1)

Where is the transplanted kidney placed? (1)

Answer 19

From cadavers 
(living donors are more unusual)

Placed extra-peritoneally in iliac fossa and anastomosed with iliac vessels.

Question 20

In what circumstances would long term immunosuppression not be required in a renal transplant? (1)

Answer 20

If the donor and recipient were genetically identical twins.

Question 21

Why is immunosuppression given long term to all renal transplant patients? (1)
Name 3 immunosuppressant medications that may be used in a patient. (3)

Answer 21

Prevent rejection

Corticosteroids
Azathioprine
Mycophenolate mofetil
Ciclosporin 
Tacrolimus

Question 22

Name 2 complications of renal transplants and immunosuppression. (2)

Answer 22

Opportunistic infection eg pneumocystis jiroveci
Hypertension
Development of tumours (skin malignancies and lymphoma)
Occasional recurrence of renal disease e.g. Goodpasture’s

Question 23

Name 2 benefits and 2 risks of renal transplantation. (4)

Answer 23

Benefits:

• Can stop dialysis.
• Improved quality of life with normal diet and activity
• Reversal of anaemia and renal bone disease.

Risks of transplantation:

• Immediate operative complications (local infection, pain, pneumonia, deep vein thrombosis).
• Immediate graft failure.
• Arterial or venous thrombosis in the transplant.
• Infections (viral, bacterial, fungal).
• Cancer (skin, lymphoma).
• Side-effects of immunosuppressive drugs.

Question 24

What is the 3 types of organ rejection? (3)

Answer 24

Hyperacute (pre-existing humoral immunity; occurs within minutes)
Acute (cellular immunity; most at risk from 1 week to 3 months after)
Chronic (occurs over years)

Question 25

Which is the least common type of rejection in kidneys? (1)

Answer 25

Hyperacute: rare because of better attaching between patients.

Question 26

What is the most common type of rejection in kidneys? (1)

Answer 26

Chronic rejection