- This is persistent microscopic hematuria, which is the recurrent presence of blood in the urine.

Hematuria is not necessarily visible to the naked eye.

The symptom that indicates a strong risk of developing chronic disease

Chronic kidney disease is a major public health problem. Its cases increased by 7% in Spain only during the year 2021, and experts consider that it is underdiagnosed because its symptoms can be difficult to identify in the initial stages of the disease.

Now, a study has found an early symptom that is closely associated with a high risk of developing this disorder: persistent hematuria (ie, the presence of blood in the urine on a recurring basis).

Only visible under a microscope

Specifically, the authors of the study, published in the specialized journal American Journal of Kidney Disease, analyzed the relationship between microscopic hematuria (the presence of blood in quantities that make it undetectable except by microscopy) and renal function in a large cohort. (more than 230,000) of healthy and relatively young adults.

At least two urine samples were taken from each patient, so that it was possible to establish the persistence of the symptom or its punctual nature, depending on each case; In the same way, they underwent at least two complete medical examinations to determine their state of health.

On the other hand, it should be noted that all those whose information in urinalysis, body mass index or serum creatinine was unknown were excluded; those who had a history of cancer; who had previously had kidney disease, who had undergone kidney surgery, who had proteinuria (abnormal levels of certain proteins in the urine), or who had developed chronic kidney disease before the second test.

A stronger association among men

Under these conditions, they found a strong association between microscopic hematuria and impaired kidney function, as well as the risk of developing chronic kidney disease. This relationship was present in those patients who had only tested positive for hematuria once, but it was much stronger in those who had tested positive in both tests.

Another interesting point that they underline in the study is the fact that the association, although it was certainly present for people of both sexes, was stronger in the case of men.

Based on all this, they recommend that patients who test positive for hematuria during routine examinations be considered candidates for monitoring their renal function and for preventive actions against chronic kidney disease.

References

Yoo Jin Um, Yoosoo Chang, Yejin Kim, Sarah H. Wild, Christopher D Byrne, Sungho Ryu et al. Risk of CKD Following Detection of Microscopic Hematuria: A Retrospective Cohort Study. American Journal of Kidney Diseases (2022). DOI: https://doi.org/10.1053/j.ajkd.2022.09.012

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