Chronic Renal Failure

Question 1

What are the common symptoms of patients suffering from chronic kidney failure?

Answer 1

Anaemia:
Malaise, loss of appetite

Renal:
Nocturia and polyuria
Insomnia (secondary to nocturia)

Uraemia:
Nausea, vomiting and diahorrea.

Fluid overload:
Leg swelling (peripheral oedema)
SOB (pulmonary oedema)

Symptom usually only occur at stage 4 renal failure

End stage renal failure can present with oliguria, however failure of tubular reabsorption will lead to very high urine output.

Question 2

What are some complications of chronic renal failure?

Answer 2

Blood:

Anaemia (reduced renal erythropoietin synthesis)

Coagulopathy

Bone disease:

Renal osteodystrophy secondary to secondary hyperparathyroidism.
Kidneys normally convert Vit D into its active form. In its active form it causes Ca reabsorption from the intestine. The Kidneys also excrete phosphate and reabsorb calcium, when damaged however they cannot do this.

The net result is low serum Ca and high phosphate. The low Ca levels result in more parathyroid hormone being produced. This means that there is increased osteoclast function and more Ca is reabsorbed from the bones causing osteodystrophy.

Fluid:

Pulmonary oedema

Hypertension

Cardiac:

Left ventricular hypertrophy
Heart failure

Neurological:

Uraemic encepalopathy

Endocrine:

Glucose intolerance due to peripheral insulin resistance

K+

Arrhythmias

Question 3

What is autosomal dominant polycystic kidney disease?

Answer 3

Inherited disorder usually presenting in adult life (40-60 half have stage CKD by 60)

Characterised by the development of multiple renal cysts. The cysts compress areas of the kidney and eventually replace much of the renal tissue.

This causes progressive renal impairment sometimes punctuated by acute episodes of loin pain and haematuria. Often associated with the development of hypertension.

Caused by PKD1 and PKD2 genes.

Question 4

Describe the pathophysiology of diabetic nephropathy?

Answer 4

Glomerular hyperfiltration (hyperglycaemia thought to cause increased cell growth in the kidneys)

Intraglomerular hypertension

Glomerular basement membrane thickening

Expansion of mesanginal cells

Nodular scelrosis

Question 5

How does diabetic nephropathy present? What is the treatment?

Answer 5

Proteinuria specifically hyperalbuminuria

Treat with ACE inhibitors

Note: usually preceded by retinopathy

Question 6

What are the initial investigations you would do for a patient with CKD?

Answer 6

To assess:

Renal function: eGFR
FBC: check for anaemia
Urinalysis: check for presence of protein
Autoantibodies screen if goodpasture’s suspected
ECG: if any complaints/signs of pulmonary oedema

Question 7

Describe the different classifications of CKD based on eGFR?

Answer 7

1 >90
2 60-89
3a 45-59
3b 30-44
4 15-29
5 Less than 15

Question 8

What are some of the signs you may find on examination?

Answer 8

Uraemia: Increased skin pigmentation, excoriation

Anaemia: Pallor

Fluids: Hypertension, postural hypotension, peripheral oedema, pleural effusions

Cardiac: left ventricular hypertrophy

Question 9

Describe how pyelonephritis can cause CKD?

Answer 9

Pyelonephritis is infection of the renal pelvis often accompanied by infection of the renal parenchyma.

It is often an ascending infection from the urinary tract..

Following infection there can be fibrosis, reduced renal function and GFR.

Question 10

What is interstitial nephritis?

Answer 10

It is inflammation of the tubule or interstitium.

Question 11

What usually causes interstitial nephritis?

Answer 11

It is usually caused by a drug hypersensitivity reaction which causes damage and necrosis in the tubo-interstitium.

Chronic intersitital nephritis is usually caused by a build up of the nephrotoxic metabolites of phenacetin/paracetamol.

Other known nephrotoxic drugs are:

• 5 ASA
• Ciclosporin
• Lithium

Question 12

How does hypertension cause renal damage?

Answer 12

Chronically high BP or very high BP causes damage and narrowing to the renal aa therefore causing hypo perfusion to the kidneys.

It can also cause damage to the capillaries supplying the nephrons causing the nephrons to die.

Question 13

How does ureteric obstruction cause renal damage and CKD?

Answer 13

Ureteric obstruction causes distal ureteric dilation (painful).

It causes there to be increased back pressure which can cause renal tubular atrophy.

In response to the back pressure the glomerulus undergoes fibrosis.

All of these mechanisms result in a decreased GFR and therefore a degree of CKD.

Question 14

Describe the type of anaemia which occurs in CKD?

Answer 14

In severe CKD (stage 4) patients often develop anaemia.

This is usually due to a reduced renal synthesis of erythropoietin. In this case the anaemia will be normochromic and normocytic.

Iron deficiency is also common in patients with CKD due to poor dietary intake. In this case the anaemia will be microchromic and microcytic.

Question 15

How should anaemia in CKD be managed?

Answer 15

Should be managed in secondary care.

Should be treated when Hb is less than 110.

Treatment should be with erythropoiesis-stimulating agents and if there is a degree of iron deficiency this should be corrected.

Contraindications of erythropoiesis stimulating agents is uncontrolled hypertension as it can increase BP as a side effect.

Question 16

How should renal bone disease be managed?

Answer 16

Bisphosphonates should be given to help protect against osteoporosis.

Vitamin D supplementation can be given if active Vitamin D levels are low.

If there is high phosphate levels due to secondary hyperparathyroidism then you can treat with:

• low phosphate diet
• phosphate binder (calcium acetate) note if serum Ca levels become high switch to a non calicum phosphate binder.

Question 17

What are the indications for dialysis?

Answer 17

Uraemia:
Pericarditis
Encephalopathy

Pulmonoary oedema

Refractive hyperkalaemia (greater than 6.5mmol)

Overdose of salicyalates or ethylene glycol

Question 18

What are the different types of dialysis?

Answer 18

Haemodialysis:
Blood is pumped from the body through a semipermeable tube surrounded with a dialysis fluid, the concentration of the fluid causes the waste products to diffuse out of the blood it is then pumped back into the body. It usually is done 4 times a week for approximately 4hrs.

Pertioneal dialysis:
Uses the peritoneum as membrane which waste products can pass between. A dialysis fluid is inserted into the peritoneum and left for a period. Over this time waste products from the blood diffuse across the peritoneum into the dialysis fluid, the fluid is then drained.
The main advantage about this is that it can be done at home by the patient the major disadvantage is that there is a significantly higher risk of infection.

Question 19

When a patient with CKD comes into hospital what is very important to consider before managing this patient?

Answer 19

What is there GFR and how will this affect there drug metabolism, refer to the BNF.