proteinuria

proteinuria

1. transient proteinuria

   • occurs
     • during febrile illness
     • after exercise
   • doesn't need ix

2. persistent proteinuria is significant

   • should be quantified
     • measure urine protein/Cr ratio in early morning sample
       • protein shouldn't >20mg/mmol of Cr

3. causes

   • orthostatic proteinuria
     • proteinuria only found when child upright i.e. during day
     • diag by measuring the urine protein/Cr in a series of early morning urine specimens
     • excellent prognosis
       • no further ix needed
   • these need further evaluation
     • glomerular abnormalities
       • minimal change disease
       • glomerulonephritis
       • abnormal glomerular basement mb (familial nephritides)
     • increased glomerular filtration Pa
     • reduced renal mass
     • hypertension
     • tubular proteinuria

4. nephrotic syn

   • heavy proteinuria ->
     • low plasma albumin
     • oedema
   • cause unknown
     • but some secondary to
       • systemic diseases
         • Henoch Scholein purpura
         • SLE
       • infections
         • e.g. malaria
       • allergens (e.g. bee sting)
   • clinical signs
     • periorbital oedema
       • esp on waking
       • the earliest sign
     • scrotal/vulval, leg & ankle oedema
     • ascites
     • breathlessness due to
       • pleural effusions
       • abdo distension
   • steroid-sensitive nephrotic syn
     • 80-90% of kids w/ nephrotic syn
       • proteinuria resolves w/ corticosteroid therapy
       • don't progress to renal failure
       • boys> girls
       • Asian> Caucasian
     • weak assoc w/ atopy
     • often ppted by resp infection
     • suggestive features
       • 1-10 years old
       • no macroscopic haematuria
       • normal bp
       • normal complement levels
       • normal renal function
     • Mx
       • initially give oral corticosteroids (60mg/m2 of prednisolone)
         • unless atypical features
         • after 4 weeks dose reduce to 40 mg/m2 on alternate days for 4 weeks
           • then stop
             • median time for urine to become protein-free= 11 days
               • extending course by alternate day dosing -> sig decrease in prop of kids w/ freq relapsing or steroid dependent course
       • Ix
         • renal histology
           • normal on light microscopy
           • e- microscopy
             • shows fusion of podocytes
               • hence aka minimal change disease
       • complications
         • hypovolaemia
           • iv albumin
             • treat increasing peripheral oedema if severe
               • assessed clinically & by daily weight
             • on seeing urinary Na <20mmol/L & high packed RBC vol
           • careful w/
             • colloid
               • can ppt pulmonary oedema & HTN from fluid overload
             • diuretics
               • cause/worsen hypovolaemia
         • infection
           • pneumococcal & seasonal influenza vaccination recommended
           • chicken pox and shingles
             • Rx: aciclovir
     • complications @ presentation or relapse
       • hypovolaemia
         • in initial phase of oedema formation intravasc comp may get vol depleted
         • c/o abdo pain, feel faint
         • peripheral vasoconstriction & urinary Na+ retention
         • indicated by low urinary Na (<20 mmol/L) & high packed cell vol of RBC
         • child @ risk of vasc thrombosis & shock
         • increasing peripheral oedema
           • may -> discomfort & resp compromise
       • thrombosis
         • hypercoagulable state due to urinary losses of antithrombin
           • thrombocytosis may be worsened by
             • steroid therapy
             • increased prodn of clotting factors
             • increased blood viscosity from raised haematocrit
           • predisposes to thrombosis
             • may affect brain, limbs & splanchnic circulation
       • infection
         • @ risk from encapsulated bacteria
           • esp Pneumococcus
             • spontaneous peritonitis may occur
       • hypercholesteraemia
         • inverse correlation w/ serum albumin, but cause of hyperlipidaemia not understood
     • prognosis
       • 1/3
         • resolve directly
         • infreq relapses
         • freq steroid-dep relapses
           • involve paed nephrologist
             • to consider other therapy to allow reduction in steroid use
               • steroid-sparing agents
                 • levamisole
                   • immunomodulator
                 • cyclophosphamide
                   • alkylating agents
                 • tacrolimus, ciclosporin A
                   • calcineurin inhibitors
                 • mycophenolate mofetil
                   • immunosuppressant
       • relapses IDed by parents on urine testing
   • Ix
     • urine protein
       • on dipstick
     • FBC
     • ESR
     • U&E, electrolytes, Cr, albumin
     • complement levels- C3, C4
     • antistreptolysin O or anti-DNAse B titres & throat swab
     • urine microscopy & culture
     • urinary [Na+]
     • hepatitis B & C screen
     • malaria screen if travel abroad
   • steroid-resistant nephrotic syn
     • refer to paed nephrologist
     • Mx
       • oedema
         • diuretics
         • salt restriction
         • ACEIs
         • NSAIDs
           • may also reduce proteinuria
     • Causes
       • focal segmental glomerulosclerosis
         • commonest
         • familial or idiopathic
         • prognosis
           • 30% prog to renal failure in 5 years
           • 20% respond to cyclophosphamide, ciclosporin, tacrolimus or rituximab
           • recurrence post-transplant is common
       • mesangiocapillary glomerulonephritis (membranoproliferative glomerulonephritis)
         • more common in older kids
         • prognosis
           • decline in renal func over many years
         • haematuria & low complement level present
       • membranous nephropathy
         • assoc w/ hep B
         • may precede SLE
         • prognosis
           • most remit spontaneously within 5 years
   • congenital nephrotic syn
     • presents in 0-3 month olds
     • recessive inheritance
       • commonest type
       • high in Finns
     • in UK common in consangineous families
     • assoc w/
       • high mortality
         • due to complications of hypoalbuminaemia
           • low albumin so severe that unilat nephrectomy may be needed to control it
             • fb dialysis for renal failure, done til child large & fit for renal transplant
   • test oedematous child for proteinuria to diagnose