Stages of renal dysfunction
| Stage |
Description |
Creatinine clearance (ml/min/1.73m2) |
Metabolic consequences |
| 1 |
Normal |
>90 |
|
| 2 |
Early renal insufficiency |
60-89 |
Inc. serum PTH |
| 3 |
Chronic renal failure |
30-59 |
Inc. Ca absorption, anaemia |
| 4 |
Pre-end stage failure |
15-29 |
Inc. TGs, PO4, K+. acidosis |
| 5 |
End stage renal failure |
<15 |
Uraemia |
- Chronic renal failure = GFR < 60 ml / min
Causes of chronic renal failure
- Chronic glomerulonephritis
- Chronic pyelonephritis
- Diabetic nephropathy
- Chronic interstitial nephritis
- Chronic obstructive uropathy
- Hypertensive nephrosclerosis
- Polycystic disease
- Amyloid
- Myeloma
Treatment of chronic renal failure
- Three basic stages in treatment
- Preserve remaining nephrons
- Conservative treatment of uraemic syndrome
- Renal dialysis and transplantation
Preserve remaining nephron function
- Control of hypertension and heart failure
- Treatment of superimposed urinary tract infection
- Correction of salt and water depletion
- Careful prescribing of drugs that are potentially nephrotoxic
- Dietary protein restriction
Conservative management of uraemic syndrome
- Reduce protein intake
- Aluminium hydroxide to reduce intestinal phosphate absorption
- Vitamin D and calcium supplements to increase serum calcium
- Allopurinol to reduce serum uric acid
- Erythropoietin to correct anaemia
Renal dialysis
Indications
- Patient aged 5-70 years without significant systemic disease or neoplasia
- Clinical deterioration despite good conservative management
- Uraemic pericarditis
- Severe renal bone disease
- Peripheral neuropathy
- Creatinine > 1,200 mmol/l
- Glomerular filtration rate < 5 ml/min
Principals
Dialysis depends on
- Diffusion = passage of solute through membrane down concentration gradient
- Ultrafiltration = passage of solvent through membrane due hydrostatic or osmotic pressure
Peritoneal dialysis
- Dialysis membrane = peritoneum
- Dialysis fluid low in urea and creatinine
- Also hypertonic solution due to high glucose concentration
- Dialysis occurs as a result diffusion and Ultrafiltration
- Tenckoff catheter usually inserted below umbilicus
Picture provided by Alireza Tavassoli, Ghaem Hospital, Mashed, Iran
- Cuffs on catheter prevent leaks and infection
- Dialysis performed on either intermittent or continuous basis
- In continuous ambulatory peritoneal dialysis fluid is changed 4 times per day
- Peritonitis is main complication
- Inefficient compared to haemodialysis
Haemodialysis
- Dialysis membrane = artificial membrane
- Pumps move blood on either side of membrane in countercurrent directions
- Solutes move across membrane by diffusion
- Vascular access obtained by:
- Arteriovenous shunt with prosthetic graft
- Arteriovenous fistula between artery and vein
- Vascular catheters in large central veins
- AV fistulas take 4-6 weeks to mature
- Can cause heart failure and steal syndrome
- Complications include aneurysm formation and haemorrhage
Picture provided by Po Ming Teng, Singapore General Hospital, Singapore
Haemofiltration
- Dialysis membrane = artificial membrane
- Used in ITU mainly for acute renal failure
- Pressure difference across membrane causes ultrafiltration
- Inefficient compared to haemodialysis
Bibliography
Gokal R, Mallick N P. Peritoneal
dialysis. Lancet 1999;
353: 823-828.
Parmar M S. Chronic renal disease. Br Med J 2002; 325: 85-90.
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