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Diabetic Kidney Disease

Background

Detection

Management

Nephrology referral guidelines

 

Background

  • Diabetes is the commonest single cause of end stage renal failure

  • About 20-30% of people with type 1 or type 2 diabetes develop some degree of diabetic kidney disease

  • The presence of microalbuminuria (early morning urinary albumin>30mg/l or urinary albumin/creatinine ratio >2.5 in men or >3.5 in women) in type 2 diabetes is often a sign of general vascular damage rather than specific renal damage. It is an important arterial risk marker

  • Raised serum creatinine in type 2 diabetes is often due to hypertensive renal damage or diuretic therapy for cardiac failure rather than to diabetic nephropathy

  • Detection and surveillance of specific kidney problems depends on identifying progression of albumin excretion rate and serum creatinine, in the absence of other causes

  • Once microalbumiuria is sustained, urinary albumin excretion tends to increase by 10-20% per year until overt diabetic nephropathy develops (urinary albumin >300mg/l or ratio>25 in men or 35 in women).

  • With the development of diabetic nephropathy, serum creatinine levels start to increase, glomerular filtration rate (GFR, or creatinine clearance) starts to fall and blood pressure tends to rise

  • The risk of developing microalbuminuria and diabetic nephropathy can be reduced by good glycaemic and blood pressure control

  • Microalbuminuria can often be reduced or eliminated using ACE inhibitors or Angiotensin II antagonists. They also help to reduce the rate of progression of diabetic nephropathy

 

Detection

  • Measure pre-breakfast urinary albumin or albumin : creatinine ratio annually

  • Urinary albumin of >30 mg/l or ratio >2.5 mg/mmol in men or >3.5 indicates microalbuminuria. Repeat to confirm and exclude infection

  • Measure serum creatinine annually, but more often if abnormal

 

Management

  • Microalbuminuria:
    - monitor albumin excretion annually
    - start ACE inhibitor or angiotensin II antagonist or both (but check for hyperkalaemia if both agents are used)
    - intensify management of arterial risk factors (glucose, lipids, blood pressure (<130/80))

  • Raised serum creatinine:
    - exclude other possible causes (hypertension, cardiac failure, infection, glomerulonephritis)
    - monitor albumin excretion and serum creatinine frequently
    - treat BP aggressively with a target of <130/80
    - reduce salt intake
    - use ACE inhibitor or Angiotensin II antagonist or both (but check for hyperkalaemia if both agents are used)
    - add loop diuretic and other agents if necessary
    - reduce protein intake with a target of <0.8 g/kg
    - treat UTI's aggressively
    - refer to a nephrologist before creatinine rises to 250 umol/l

 

Nephrology referral guidelines

  • Persistent microscopic haematuria in the absence of demonstrable urinary infection

  • Hypertension which is proving particularly difficult to control in the presence of microalbuminuria or diabetic nephropathy

  • Proteinuria in the nephrotic range, manifest as either >3g/24h or hypoalbuminaemia

  • Serum creatinine >250 micromol/l regardless of calculated GFR (see below)

  • Reduction in calculated GFR (see below) of >15ml/min when started on an ACE inhibitor

  • Progressive deterioration in calculated GFR of >15ml/min per annum

  • Calculated GFR of below 40ml/min

  • GFR calculation - The Cockroft-Gault method uses serum creatinine, age, gender and weight to calculate creatinine clearance. It can be easily accessed on www.nephron.com