A Diagnostic approach to Proteinuria

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Diagnostic Evaluation of Proteinuria
Microscopic Urinalysis

When proteinuria is found on a dipstick urinalysis, the urinary sediment should be examined microscopically. The findings of the microscopic examination and associated disorders are summarized in Table 5. Dysmorphic erythrocytes are a result of cell insult secondary to osmotic shift in the nephron, indicating glomerular disease. Gross hematuria will cause proteinuria on dipstick urinalysis, but microscopic hematuria will not.

Findings suggestive of infection on microscopic urinalysis mandate antibiotic treatment and then repeated dipstick testing. Nephrology consultation may be warranted if sediment findings indicate underlying renal disease.

Transient Proteinuria

If the results of microscopic urinalysis are inconclusive and the dipstick urinalysis shows trace to 2+ protein, the dipstick test should be repeated on a morning specimen at least twice during the next month (when proteinuria [3+ or 4+] is
found on a dipstick urinalysis, work-up should proceed to a quantitative evaluation of a specimen).

If a subsequent dipstick test result is negative, the patient has transient proteinuria. This condition is not associated with increased morbidity and mortality, and specific follow-up is not indicated.

Interpretation of Findings on Microscopic Examination of Urine
Microscopic finding Pathologic process
Fatty casts,free fat or oval fat bodies Nephrotic range proteinuria (>3.5 g per 24 hours)
Leukocytes, leukocyte casts with bacteria Urinary tract infection
Leukocytes,leukocyte casts without bacteria Renal interstitial disease
Normal-shaped erythrocytes Suggestive of lower urinary tract lesion
Dysmorphic erythrocytes Suggestive of upper urinary tract lesion
Erythrocyte casts Glomerular disease
Waxy,granular or cellular casts Advanced chronic renal disease
Eosinophiluria * Suggestive of drug-induced acute interstitial nephritis
Hyaline casts

No renal disease;present with dehydration and with diuretic therapy

*A Wright stain of the urine specimen is necessary to detect eosinophiluria

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