ORTHOSTATIC PROTEINURIA
 
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ORTHOSTATIC PROTEINURIA

 

DEFINITION:

A benign asymptomatic form of proteinuria that occurs only when the child is upright and absent when supine.

EPIDEMIOLOGY:

  • incidence: accounts for 60% of all cases of childhood proteinuria and >60% of all cases of adolescent proteinuria
  • age of onset:
    • childhood -> adolescence
  • risk factors:
    • F > M up to 16 years of age then M > F

PATHOGENESIS:

1. Background

  • unknown etiology but altered renal hemodynamics may have an effect on glomerular protein handling
  • three subtypes: transient, intermittent, persistent (fixed)

CLINICAL FEATURES:

1. Renal Manifestations

1. Proteinuria

  • asymptomatic
  • never associated with edema
  • may be transient or persistent

INVESTIGATIONS:

1. Postural Test

1. Qualitative

  • spot urinalysis:
    • negative to trace (am)
    • greater than or equal to 1+ (pm)

2. Quantitative

  • collect two 12 hour specimens, a finding of normal protein excretion in the supine (am) collection of <150 mg and an elevated protein excretion in the upright (pm) collection (up to 1 gm) suggests orthostatic proteinuria
  • to exclude a glomerular disease must excrete:
    • <1 gm of protein/day
    • <100 mg/m2/day
    • <1.5 g/1.73m2/day
  • no hematuria
  • Note: orthostatic proteinuria may represent the first manifestation of a glomerular lesion

2. Serum

  • normal C3 and creatinine clearance

3. Renal Biopsy

  • normal

MANAGEMENT:

1. Supportive

  • repeat urinalysis in 1 year

2. Prognosis

  • excellent and independent of subtype
  • does not lead to progressive disease

3. Instructions For Testing For Orthostatic Proteinuria*

  • 1. Patient voids at bedtime. Discard urine. No food or fluids after dinner until the next morning.
  • 2. When patient awakes in the morning, urine specimen is collected prior to arising, or after as little ambulation as possible. Label specimen #1.
  • 3. Child should ambulate for the next 2 to 3 hours. Then collect specimen. Label specimen #2.
  • 4. Both specimens should be tested by dipstick or sulfosalicylic acid. Specimen #1 should be concentrated with a specific gravity of at least 1.018.
  • 5. If specimen #1 is free of protein and specimen #2 has protein, then the test is positive for orthostatic proteinuria.
  • 6. If both specimens have protein, orthostatic proteinuria is unlikely and further evaluation is necessary.
  • 7. This protocol should be repeated on at least 2 occasions to confirm the diagnosis.

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  • * protocol obtained from Dr. Matsell at CHWO.

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