Presentation on theme: "EVALUATION OF ASYMPTOMATIC PROTEINURIA IN CHILDREN"— Presentation transcript:
1 EVALUATION OF ASYMPTOMATIC PROTEINURIA IN CHILDREN By: Patricia Baile
2 MECHANISMS OF PROTEIN HANDLING BY KIDNEY Glomerular capillary wall permits passage of small molecules while restricting macromolecules
3 3 components of glomerular wall Endothelial cellBasement membraneEpithelial cell
4 MECHANISMS OF PROTEIN HANDLING BY KIDNEY Glomerular permeabilitySteric hindrance: due to spatial alignment of the passing molecules, relative to membrane poresViscous drag: impedance to movement caused by fluid lining the poresElectrical hindrance: due to electrostatic repulsion between epithelial surface and plasma proteins
5 MECHANISMS OF PROTEIN HANDLING BY KIDNEY Normal protein excretion affected by interplay of glomerular and tubular mechanismsGlomerular injury: abnormal losses of intermediate MW proteins like albuminTubular damage: increased losses of low MW proteins
6 NORMAL PROTEIN EXCRETION Child: < 100mg/m2/day or 150mg/dayNeonates: up to 300mg/m2
7 ABNORMAL PROTEIN EXCRETION Urinary protein excretion in excess of 100 mg/m2 per day or 4 mg/m2 per hourNephrotic range proteinuria (heavy proteinuria) is defined as ≥ 1000 mg/m2 per day or 40 mg/m2 per hour.
8 ABNORMAL PROTEIN EXCRETION Glomerular proteinuriaDue to increased filtration of macromoleculesMay result from glomerular disease (most often minimal change disease) or from nonpathologic conditions such as fever, intensive exercise, and orthostatic (or postural) proteinuria
9 ABNORMAL PROTEIN EXCRETION Tubular proteinuriaResults from increased excretion of low molecular weight proteins such as beta-2-microglobulin, alpha-1- microglobulin, and retinol-binding proteinTubulointerstitial diseases, can lead to increased excretion of these smaller proteins
10 ABNORMAL PROTEIN EXCRETION Overflow ProteinuriaResults from increased excretion of low molecular weight proteins due to marked overproduction of a particular protein to a level that exceeds tubular reabsorptive capacity
11 ASYMPTOMATIC PROTEINURIA Levels of protein excretion above the upper limits of normal for ageNo clinical manifestations such as edema, hematuria, oliguria, and hypertension
12 MEASUREMENT OF URINARY PROTEIN Urine dipstickMeasures albumin concentration via a colorimetric reaction between albumin and tetrabromophenol blue producing different shades of green according to the concentration of albumin in the sampleNegativeTrace — between 15 and 30 mg/dL1+ — between 30 and 100 mg/dL2+ — between 100 and 300 mg/dL3+ — between 300 and 1000 mg/dL4+ — >1000 mg/dL
13 MEASUREMENT OF URINARY PROTEIN Sulfosalicylic acid testDetects all proteins in the urine including the low molecular weight proteins that are not detected by the dipstickPerformed by mixing one part urine supernatant (eg, 2.5 mL) with three parts 3 percent sulfosalicylic acid, followed by assessment of the degree of turbidity
14 MEASUREMENT OF URINARY PROTEIN Quantitative assessmentChildren with persistent dipstick-positive proteinuria must undergo a quantitative measurement of protein excretion, most commonly on a timed 24-hour urine collectionIn children: levels >100 mg/m2 per day (or 4 mg/m2 per hour) are abnormalProteinuria of greater than 40 mg/m2 per hour is considered heavy or in the nephrotic range
15 MEASUREMENT OF URINARY PROTEIN Quantitative assessmentAlternative method of quantitative assessment is measurement of the total protein/creatinine ratio (mg/mg) on a spot urine sample, preferably the first morning specimenFor children >2 yrs: normal value for this ratio is <0.2 mg protein/mg creatinineFor infants and children <2yrs: <0.5 mg protein/mg creatinine
17 TRANSIENT PROTEINURIA Most common causeCan occur in association with fever, seizures, strenuous exercise, emotional stress, hypovolemia, extreme cold, epinephrine administration, abdominal surgery, or congestive heart failureBelieved to be glomerular in origin, related to hemodynamic changes (decreased renal plasma flow) rather than altered permeability of capillary wall
18 ORTHOSTATIC PROTEINURIA Increase in protein excretion in the erect position compared with levels measured during recumbencyProteinuria usually does not exceed gm/dayMechanism postulated to involve an increased permeability of the glomerular capillary wall and a decrease in renal plasma flowLong-term studies have documented the benign nature of this condition, with recorded normal renal function up to 50 years later
19 PERSISTENT PROTEINURIA Present for long periods after initial detectionAbsence of both orthostatic proteinuria and clinical evidence of renal diseaseClinical course may be benignMay be secondary to parenchymal disease
20 DIFFERENTIAL DIAGNOSES OF PERSISTENT PROTEINURIA Benign proteinuriaAcute Glomerulonephritis, mildChronic Glomerular Disease that can lead to nephrotic syndromeChronic nonspecific glomerulonephritisChronic interstitial nephritisCongenital and acquired structural abnormalities of urinary tract
24 PHYSICAL EXAMINATION Vital signs Inspect for presence of edema, pallor, skin lesions, skeletal deformitiesScreening for hearing and visual abnormalitiesAbdominal examLung examCardiac exam
25 LABORATORY EVALUATION Single urine positive for protein1) first morning void Pr/Cr2) UA in officeObtain:Pr/Cr and UA normalTransient ProteinuriaPr/Cr normal, UA positiveOrthostatic ProteinuriaBoth specimens abnormalPersistent Proteinuria
26 TRANSIENT PROTEINURIA Follow-up routinelyPatient should have a repeat urinalysis on a first morning void in one year
27 ORTHOSTATIC PROTEINURIA Perform Orthostatic TestCBCBUNCreatinineElectrolytes24-hr urine excretion< 1.5g/day repeat UA and blood work in 1 year> 1.5g/day refer to Pediatric Nephrologist
28 Instructions for Testing for Orthostatic Proteinuria Patient voids at bedtime. Discard urine. No food or fluids after dinner until the next morning.When patient awakes in the morning, urine specimen is collected prior to arising, or after as little ambulation as possible. Label specimen #1.Child should ambulate for the next 2 to 3 hours. Then collect specimen. Label specimen #2.Both specimens should be tested by dipstick or sulfosalicylic acid. Specimen #1 should be concentrated with a specific gravity of at leastIf specimen #1 is free of protein and specimen #2 has protein, then the test is positive for orthostatic proteinuria.If both specimens have protein, orthostatic proteinuria is unlikely and further evaluation is necessary.This protocol should be repeated on at least 2 occasions to confirm the diagnosis.
29 FURTHER EVALUATION OF PERSISTENT PROTEINURIA Examination or urine sedimentCBCRenal function tests (blood urea nitrogen and creatinine)Serum electrolytesCholesterolAlbumin and total protein
30 OTHER TESTS Renal ultrasound Serum complement levels (C3 and C4) ANA Streptozyme testing,Hepatitis B and C serologyHIV testing
31 PERSISTENT PROTEINURIA If further work-up normal, urine dipstick should be repeated on at least two additional specimens. If these subsequent tests are negative for protein, the diagnosis is transient proteinuria.If the proteinuria persists or if any of the studies are abnormal, the patient should be referred to a pediatric nephrologistUrinary protein excretion should be quantified by a timed collection
32 INDICATIONS FOR RENAL BIOPSY Many nephrologists recommend close monitoring for those children with urinary protein excretion below 500 mg/m2 per day before considering a biopsyMonitoring should include assessment of blood pressure, protein excretion, and renal function. If any of these parameters shows evidence of progressive disease, a renal biopsy should be performed to establish a diagnosis.
33 MANAGEMENT Avoid excessive restrictions in child’s lifestyle Dietary protein supplementation is of no benefitSalt restriction unnecessary and potentially dangerousNo indication for limitation of activityImportance of compliance with regular follow-up should be stressed
34 REFERENCESUpToDateFeld L, Schoeneman M, Kaskel F: Evaluation of the Child with Asymptomatic Proteinuria. Pediatrics in Review 1984; 5:Nelson’s Textbook of Pediatrics
Your consent to our cookies if you continue to use this website.