American Journal of Kidney Diseases
Volume 53, Issue 1 , Page 180, January 2009

Urinary Albumin–Total Protein Ratio: A New Diagnostic Tool to Differentiate Glomerular From Nonglomerular Hematuria?

Radboud University, Nijmegen Medical Center, Nijmegen, The Netherlands

Article Outline

 

To the Editor:

In their interesting paper, Ohisa et al argue that the urinary albumin–total protein ratio allows to distinguish between glomerular and nonglomerular hematuria with high accuracy.1 However, a thorough look at the data indicates that the usefulness of this diagnostic test is limited in everyday clinical practice. First, the study population used by Ohisa et al to calculate the sensitivity and specificity of the test contained a considerable number of patients in whom such a test was not required to make a diagnosis. For example, in clinical practice, no one would order a diagnostic test to demonstrate the presence of glomerular hematuria in patients with nephrotic syndrome, or the presence of nonglomerular hematuria after prostate biopsy. Indeed, the distinction between glomerular and nonglomerular hematuria is especially challenging in patients with asymptomatic, microscopic hematuria. Notably, several authors have reported that 40% to 50% of patients with microscopic hematuria have a normal urinary albumin concentration,2, 3 and in these cases the urinary albumin–total protein ratio cannot be calculated. Therefore, the diagnostic test characteristics reported by Ohisa et al are not applicable to the population that poses the main diagnostic dilemma in clinical practice. Consequently, we believe that examination of the urinary sediment by an experienced person remains a major diagnostic tool. Examination of the urinary sediment is possible in every patient and, contrary to what Ohisa et al suggest, can even be performed after preservation of the sediment for several weeks.4

Back to Article Outline

Acknowledgements 

Financial Disclosure: None.

Back to Article Outline

References 

  1. Ohisa N, Yoshida K, Matsuki R, et al. A comparison of urinary albumin-total protein ratio to phase-contrast microscopic examination of urine sediment for differentiating glomerular and nonglomerular bleeding. Am J Kidney Dis. 2008;52:235–241
  2. Auwardt R, Savige J, Wilson D. A comparison of the clinical and laboratory features of thin basement membrane disease (TBMD) and IgA glomerulonephritis (IgA GN). Clin Nephrol. 1999;52:1–4
  3. Shen P, He L, Li Y, Wang Y, Chan M. Natural history and prognostic factors of IgA nephropathy presented with isolated microscopic hematuria in Chinese patients. Nephron Clin Pract. 2007;106:C157–C161
  4. van der Snoek BE, Koene RA. Fixation of urinary sediment. Lancet. 1997;350:933–934

 Ohisa et al declined to respond.

PII: S0272-6386(08)01570-9

doi:10.1053/j.ajkd.2008.08.034

American Journal of Kidney Diseases
Volume 53, Issue 1 , Page 180, January 2009

Article Tools