Chronic Kidney Disease for the Generalist

 

Protect those nephrons!  From AMR this week, a handy primer on CKD for your continuity clinic.  

When do your patients have CKD? Decline in GFR for >3 months PLUS Evidence of Kidney Disease (evidenced by one of the following)

  • ›Albuminuria
  • ›Urine sediment abnormalities
  • ›Electrolyte and other abnormalities due to tubular disorders
  • ›Abnormalities detected by histology
  • ›Structural abnormalities detected by imaging
  • ›History of kidney transplantation

Figure out what caused it: 75% are HTN and/or Diabetes

  • Glomerular disease
  • Obstructive uropathy
  • Vascular diseases
  • Hepatorenal/cardiorenal syndromes
  • Congenital disease: PKD

Do the workup:

  • GET THE UA  Active sediment/proteinuria vs a bland UA will be a major branch point in your evaluation, so you have to get a UA.  Spot urine protein and creatinine are also useful.
  • US Looking for cystic kidneys, hydronephrosis, asymmetry, or even symmetric evidence of “medical renal disease” is useful.
  • Based on historical clues, you can also check: HIV, hepatitis serologies, SPEP/UPEP, ANA, ANCAs

Stage it: based on GFR. VGFR- MDRD and CKD-EPI are most commonly used formulas. Here’s a handy calculator that gives you both, plus the stage.

Stage Description GFR
1 Kidney damage with nl GFR >90
2 Kidney damage with increased GFR 89-60
3a Moderately decreased GFR 59-45
3b 44-30
4 Severely decreased GFR 29-15
5 Kidney failure <14 or on dialysis

 

Call for Backup: Nephrology Referral

  • You don’t know why the patient has kidney disease
  • It is progressing quickly (loss of 50% of their GFR within one year)
  • Nephrosis: Lots of proteinuria (>3g/day)
  • Nephritis: active urine sediment with blood, protein, casts
  • Dialysis planning: sometime during stage3b is probably ideal, certainly by the time patient has GFR <30
    • Mortality benefit for patients that see nephrology earlier.

OK, now what?  Manage it:

  • Fix reversible causes: remove nephrotoxins, relieve obstruction, treat CHF/Cirrhosis/HIV/Hepatitis
  • Slow progression
    • HTN: JNC8 guidelines recommend goal 140/90
    • DM: ACCORD trial showed benefit with treatment to HbA1c <7.5
    • Add an ACE-inhibitor or ARB if there is proteinuria
  • Aggressive cardiovascular risk reduction (Cardiovascular disease is going to kill these patients before the renal disease does- see graph below)
  • Deal with the complications

CV mortality in CKD

Sarnak M J et al. Circulation. 2003;108:2154-2169

What Complications?

  • Hyperkalemia: Lasix helps
  • Anemia: Replace Iron, consider EPO if Hgb <10
  • Acidosis: consider when serum bicarb <22
  • Volume Overload: Lasix helps
  • Mineral Bone Disease: replace Vitamin D, bind PO4

Great posts by our own Dr.Centor on CKD here (don’t miss the comments) and here.

2012 KDIGO Guidelines for the evaluation and management of CKD.

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