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Kidney Week

Abstract: SA-PO969

Urinary Acanthocytes and Red Blood Cell Casts for the Diagnosis of Glomerulonephritis and Its Crescentic Forms

Session Information

Category: Glomerular Diseases

  • 1402 Glomerular Diseases: Clinical, Outcomes, and Trials

Authors

  • Stark, Ana Isabel, Ochsner Health, New Orleans, Louisiana, United States
  • Kanduri, Swetha Rani, Ochsner Health, New Orleans, Louisiana, United States
  • Ramanand, Akanksh, Ochsner Health, New Orleans, Louisiana, United States
  • Varghese, Vipin, Ochsner Health, New Orleans, Louisiana, United States
  • Chalmers, Dustin R., Ochsner Health, New Orleans, Louisiana, United States
  • Abdeen, Mu'ath Nedal, Ochsner Health, New Orleans, Louisiana, United States
  • Mohamed, Muner, Ochsner Health, New Orleans, Louisiana, United States
  • Lukitsch, Ivo, Ochsner Health, New Orleans, Louisiana, United States
  • Velez, Juan Carlos Q., Ochsner Health, New Orleans, Louisiana, United States
Background

Identification of urinary acanthocytes (uAc) is fairly specific for the diagnosis of glomerulonephritis (GN), but it is perceived as having suboptimal sensitivity. We hypothesized that combining the finding of urinary red blood cell casts (uRBCC) with uAc for the diagnosis of GN, the sensitivity of urine microscopy (uMICRO) as a whole can be optimized. Furthermore, whether uAc provides diagnostic value for identification of more severe (ie, crescentic) forms of GN is unknown.

Methods

Records of patients seen in nephrology consultation who had a uMICRO over a 5-year period were reviewed. We identified cases in which a kidney biopsy was performed within 2 weeks of the uMICRO. We assessed the performance of uAc alone and that of uAc in combination with uRBCC for the diagnosis of biopsy-proven GN or for any glomerular disease (GD). In addition, we evaluated the performance of uAc for the identification of crescentic forms of GN.

Results

Of 747 patients who underwent uMICRO, 217 underwent kidney biopsy. Mean age was 56, 51% women, 47% White, 7% Hispanic, 41% Black. Mean serum creatinine was 3.5 mg/dL. Biopsy diagnosis was GD in 77%, GN in 54%, and others in 23%. The sensitivity (SENS), specificity (SPEC), positive predictive value (PPV) and negative predictive value (NPV) of uAc for diagnosing GN were 62%, 85%, 75% and 76%, respectively. Combining the presence of either uAc or uRBCC, the SENS, SPEC, PPV and NPV changed to 69%, 100%, 100% and 64%, respectively. When examining uAc to predict any form of GD, the SENS, SPEC, PPV and NPV were 45%, 100%, 100% and 35%, respectively. As for crescentic GN, either uAc or uRBCC were found in 29 out of 33 (88%). The SENS, SPEC, PPV and NPV of uAc for crescentic GN were 88%, 42%, 47% and 86%, respectively. Notably, uAc were comnon in IgA nephropathy (71%), pauci immune ANCA (81%), and infection-related GN (IRGN) (83%), but uncommon in lupus GN (29%).

Conclusion

With proficient examiners and well-equipped laboratory, identification of uAc and uRBCC by uMICRO aid in the diagnosis of GN. uAc are pathognomonic of GD. Crescentic forms of GN and certain pathologies (IgA nephropathy, pauci immune ANCA, IRGN) most commonly present with uAc and/or uRBCC.