Immunoglobulin A nephropathy (IgAN) is a glomerular disease which can lead to kidney failure. Between 70 and 100 percent of all IgAN patients also are diagnosed with microscopic hematuria, but researchers are still unclear as to how hematuria may be involved in disease progression.

The controversy is quite strong. While some say there is no correlation regarding microhematuria and progression, others say it is a large risk factor.

One study conducted in China shows that there is a strong correlation.

The Study

This study included a total of 1,333 patients who were all diagnosed with IgAN. About half of the patients were male and the average age was about 35. At the start-

• Median estimated glomerular filtration rate (eGFR) = 62.2 ml/min/1.773 m²
• Median protein exertion = 1.31 g/d
• Mean arterial pressure = 73 mm Hg
• 645 were hypersensitive
• Hematuria = 12.50 RBC/HPF (annual method)
• Hematuria = 97.60 RBC/mL (automated method)
• 375 patients had a history of microhematuria

They first evaluated microhematuria in urine samples. The team calculated the average level of hematuria every 6 months for a total of 45 months.

The primary endpoint was the development of kidney failure or a 50% decline in eGFR. Remission was classified as a red blood count of less than or equal to 5 on average for the manual technique and less than or equal to 28 for the automated technique.

Results

• 207 had a composite kidney disease progression event
• 123 experienced kidney failure
• Both hematuria measuring techniques had a strong correlation
• In the first six months, patients in remission had a higher chance of having hypertension.
• 639 patients were given steroids
  • Of these patients, a greater percentage had hematuria at the start of the study compared to those who did not have an immunosuppressive therapy
• Time-varying hematuria was found to be a factor for increased kidney disease progression.
  • These outcomes were similar across manual and automated measures.
• A strong link was found between remission of hematuria and less risk for composite progression events.
• No association found between remission of hematuria and improved survival for those in proteinuria remission.

Looking Forward

Despite the limitations of this study (one trial center, one ethnicity, etc.), it provides strong evidence that microhematuria could be used as a part of the scoring system to determine risk for renal outcomes.

Not only did this team find that hematuria remission leads to decreased incidence of disease progression, they found that this effect was more pronounced in those without remission of proteinuria.

Finally, this study indicates that both manual and automated measuring techniques for hematuria produce similar results.

You can read more about this study here.