✆ Common Calls ✆
Proteinuria

Urine protein-creatinine ratio (UPC):

• <2 years old: >0.5 mg/mg (500 mg/g) is abnormal

• >2 years old: >0.2 mg/mg (200 mg/g) is abnormal

  • "Low-grade" proteinuria: UPC 0.2-0.5

  • "Moderate" proteinuria: UPC 0.5-2

  • "Nephrotic-range" proteinuria: UPC >2

    • Sometimes defined as UPC >3

24-hour urine collection:

• *** grams of protein/24 hours

  • Note: this is irrespective of urine creatinine

  • "Nephrotic-range" proteinuria:

    • 40 mg/m²/h in children

    • >3.5 g/24h in adults

Urine microalbumin/creatinine ratio (UAC):

• Normal: <30 mcg/mg Cr

• Microalbuminuria: 30-300 mcg/mg Cr

• Macroalbuminuria: 300 mcg/mg Cr

"Persistent" proteinuria:

• ***# of samples? How far apart?

Orthostatic (postural) proteinuria:

• ***definition

• First-morning urine protein/creatinine ratio (UPC) is the best approximation of a 24-hour urine collection

  • Presumably the patient will have been supine while sleeping, which helps to rule out orthostatic proteinuria (a benign cause of proteinuria on daytime voids)

• Ensure sample is from first-morning void to rule out orthostatic proteinuria with an laboratory UA (not just POC dip in clinic)

• Pay attention to the urine creatinine. If the urine creatinine is low, the elevated UPC may overestimate the actual protein excretion.

• If concerned for tubular proteinuria, consider sending a urine albumin/creatinine ratio (UAC), which is more specific for glomerular proteinuria.

Inadequate sample:

• If not first-morning sample {in what age group?}, repeat as a first-morning void

• If urine creatinine very low, consider a 24 hour urine collection

  • May be infeasible depending on the patient's continence status and ability to cooperate

Persistent proteinuria:

• "Low-grade" proteinuria:

  • Monitor (***how?)

  • ACEi unlikely to be of benefit

• "Moderate" proteinuria (UPC 0.5-2):

  • Consider ACEi to suppress proteinuria

  • Consider biopsy to investigate etiology

• "Nephrotic-range" proteinuria: see nephrotic syndrome (NS)

  • If clinical picture inconsistent with nephrotic syndrome (especially if not hypoalbuminemic), consider a 24-hour urine protein measurement

ACEi/ARB for proteinuria in CKD:

• Check UPro/Cr for total proteinuria. If Alb/Cr is minimal or absent, but Pro/Cr is high/abnormal, you’re probably looking at tubular proteinuria, which ACEi won’t help

• If not, then your patient should probably be on ACEi/ARB, provided their GFR isn’t below CKD stage 4 (< 30ml/min/1.73m2)

  • Some attendings who will continue to use ACEi/ARB below CKD stage 4. Indeed, there is no evidence to support there is harm in using ACEi/ARBs in advanced CKD, except for hyperkalemia as contraindication