Chronic Kidney Disease

Patient with history of obesity, HTN, and DM type 2 presents with decreased renal function for > 3 months. Decreased urine output, continued unhealthy diet, and progression of diabetic retinopathy on yearly ophthalmologic exam. Denies recent illness, flank pain, pruritic rash. Denies family history of renal disease. HTN with decreased visual acuity on exam. No JVD, M/R/G, abdominal bruit, flank pain, suprapubic tenderness, LE edema, joint swelling/tenderness, rash on exam. Dorsalis pedis pulse 2+ bilaterally.

  • Labs

    • Obtain CBC, CMP, lipid panel, HbA1c, urinalysis, urine culture, morning spot urine albumin/creatinine ratio; GFR calculated using National Kidney Foundation (NKF) calculator <60 mL/min/1.73 m^2

    • Hgb indicates anemia: Obtain reticulocyte count, ferritin level, transferrin saturation, and vitamin B12/folate levels

    • No urine sediment or casts noted on microscopy

  • Imaging

    • Obtain renal ultrasound with Doppler to rule out structural disease, decreased perfusion

    • Consider nerve conduction study if pt develops paresthesias or s/sx consistent with restless leg syndrome

  • Blood pressure management per KDIGO for adults with and without DM

    • Hypertension and not pregnant: Start lisinopril 2.5 (GFR < 30) to 10 mg (GFR > 30) qd for renal protection and titrate to 40 mg daily with close monitoring of serum potassium and creatinine

    • Albumin-creatinine ratio

      • < 30 mg/24h: Treat to ≤ 140/90 mmHg

      • ≥ 30 mg/24h: Treat to ≤ 130/80 mmHg with at least one ACE-I or ARB

    • Monitor for postural hypotension

  • Treatment per stage (KDIGO recommendations, see notes for shared decision making considerations)

    • All patient stage ≥ 3a (GFR < 60)

      • Obtain annual CBC (anemia) and baseline CMP, phosphorous, PTH

      • Serum bicarbonate < 22 mmol/L: Start oral bicarbonate supplementation

      • Elevated PTH: Obtain serum 25-hydroxyvitamin D and supplement to > 20 ng/mL

      • Administer pneumococcal 23 vaccination

      • Refer to nutrition to discuss caloric, protein, sodium, potassium, and phosphate intake

    • Stage 3b (GFR 30-44)

      • Obtain annual CMP, serum phosphate

      • Do not perform routine bone mineral density testing (risk for misleading results)

      • Maintain serum phosphate concentrations within normal range

    • Stage 4 (GFR 15-29)

      • Obtain CBC every 6 months

      • Immunize against hepatitis and confirm response with HBV Ab

      • Do not administer bisphosphonate therapy

      • Prepare for renal replacement therapy

    • Stage 5 (GFR < 15): Refer to nephrology for initiation of dialysis

  • Medication

    • GFR < 60: Avoid sodium-phosphate bowel preparations

    • Uremic pruritus: Chronic condition common in advanced CKD. Trial of capsaicin cream and/or mirtazapine.

  • Refer to nephrology for any of the following:

    • GFR <30 mL/min/1.73 m^2

    • Potassium levels persistently > 5.0 meq/L

    • Two of three early morning spot urine albumin/creatinine ratio > 300 mg/g and spot urine protein/creatinine ratio > 500 mg/g

    • Development of anemia of chronic disease

  • Imaging with contrast: Hydrate before/after study and reevaluate GFR within 48-96 hours

Notes

Diagnosis

  • Differential includes alternate etiologies that may be indicated by recent illness, urine sediment/casts on microscopy, etc.

    • Acute: AKI (Cr 1.5-1.9 x baseline or Cr increase > 0.3 mg/dL), UTI, nephrolithiasis

    • Chronic: Autoimmune disease, familial kidney disease

    • Acute or chronic: Medication use, intrinsic renal disease

  • CKD diagnostic criteria: Must meet one of the following for > 3 months

    • GFR < 60 ml/min/1.73 m^2

    • Any marker of kidney damage: Albuminuria ≥ 30 mg/24 hours, electrolyte/urine sediment/structural/histologic abnormality, history of renal transplant

Determining Renal Function

  • CKD categorized per GFR (see KDIGO chart, NKF calculator) and albuminuria

  • Creatinine

  • Albuminuria

    • Term “microalbuminuria” no longer recommended

    • Spot urine albumin/creatinine ratio (ACR)

      • Can be collected at any time

      • Confirm ACR ≥ 30 mg/g with early morning urine sample

      • Greater values indicate increased risk for progression to ESRD and death

    • Suspicion for false elevation due to multiple myeloma: Obtain urine kappa/lambda light chain assay (Bence-Jones protein)

  • Cockcroft-Gault equation

    • Only used for medication adjustments

    • Calculation becomes increasingly important in elderly patients as GFR declines with age. For example, in two 70 kg male patients with Cr 1:

      • GFR in the 40 y/o = 44 mL/min

      • GFR in the 80 y/o = 26 mL/min

Dialysis Considerations