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DIABETIC KIDNEY DISEASE

Diabetic kidney disease is a major caused of morbidity and premature death, in diabetic patients.

It is multistage condition that requires many years before becoming clinically overt.

An estimated 5% to 15% of DM 2 cases also progress through the five stages of diabetic nephropathy (DN), but the timeline is not as clear. Some patients advance through the stages very quickly.

For a chart on the five stages associated with diabetic nephropathy and the albumin excretion, GFR and BP at each stage see Appendix 11a

Risk factors for the development of diabetic nephropathy are:

Hyperglycaemia
Raised blood pressure
Baseline urinary albumin excretion
Increasing age
Duration of diabetes
Presence of retinopathy
Smoking
Genetic factors
Raised cholesterol and triglyceride levels
Male sex
Raised serum homocysteine levels.



MICROALBUMINURIA

Incipient nephropathy is the stage of microalbuminuria;
Albumin excretion can be estimated through the following methods:

  1. 24 hour urine collection.
  2. Timed collection, say over a period of four hours.
  3. Spot urinary sample

The results are analysed as follows:

  24 hour collection Timed collection Spot collection
  mg / 24 hours ug / min ug/mg Creatinine
Normal < 30 < 20 < 30
Microalbuminuria 30 - 300 20 - 200 30 - 300
MacroAlbuminuria > 300 > 200 > 300

Urinary albumin excretion (UAE) has a marked intra-individual day to day variation which may be up to 50% thus, in patients with an increase in the urinary albumin excretion rate, or a persistent proteinuria, the UAE should be measured in sterile urine on 3 different intervals over a 4-6 month period;

Albumin to creatinine ratio >30mg/g in an untimed urine specimen is a good predictor of the development of overt nephropathy during an 8 year followup period

Other condition which lead to an increase in UAE should be ruled out; more than 30% patients with raised UAE and/or persistent proteinuria may have an extra renal cause;

For a partial list of common "non diabetic" causes of raised urinary albumin excretion see Appendix 11b

INCIPIENT DIABETIC NEPHROPATHY (DIABETIC MICRO ALBUMINURIA) SHOULD ONLY BE DIAGNOSED WHEN SEEN TO BE PRESENT ON REPEAT TESTING AND WHEN OTHER CAUSES OF RAISED URINARY ALBUMIN HAVE BEEN EXCLUDED.

If tests for microalbuminuria are negative, RETEST regularly.

MANAGEMENT strategies for microalbuminuria
  1. Meticulous glycemic control.
  2. Exclude other causes for microalbuminuria
  3. Meticulous control of blood pressure and dyslipidemias, if present.
  4. Avoid dehydration.
  5. Prompt diagnosis and meticulous management of urinary tract infections.
  6. Use of ACE inhibitors (ACEIs) even in normotensive patients. Angiotensin Receptor Blockers (ARBs) used alone or in combination with ACEIs seem to be a better alternative, but more studies are necessary before this recommendation can be made as routine therapy.

MANAGEMENT strategies in clinical nephropathy
  1. meticulous glycemic control.
  2. tight control of blood pressure, with the aim to maintain the BP as close to 120/80 as possible, although this needs to be individualised i.e., older patients may have more leeway;
  3. cessation of smoking.
  4. salt restriction.
  5. protein restriction (0.4.0.6mg/kg/day).
  6. treat associated lipid disorders.
  7. check for urinary tract infection; exclude other causes for renal dysfunction.
  8. avoid dehydration.
  9. caution against use of drugs which harm renal function and radio graphic dyes; this should always be done in any diabetic, but all the more in patients with clinical nephropathy.

End Stage Renal Disease

Renal replacement therapy (dialysis and / or renal transplant) is the treatment for end stage renal disease (ESRD).



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