MicroRNAs (miRNAs) are small, non-coding RNA molecules that regulate biological processes by interacting with messenger RNAs. They are present in various body fluids, including serum, plasma, saliva, and urine, and have been associated with pathological conditions such as cancer. This study examined the presence of miRNAs in 12 human body fluids, including urine samples from individuals with different urothelial conditions. Using quantitative PCR, the researchers conducted a global survey of miRNA distribution in these fluids. The results showed that miRNAs were present in all tested fluids and exhibited distinct compositions in different fluid types. Some miRNAs were common among multiple fluid types, while others were enriched in specific fluids. The study also observed distinct miRNA patterns in urine samples from individuals with different physiopathological conditions. The findings suggest that miRNAs are ubiquitous in all tested body fluids and may have functional roles associated with surrounding tissues. The changes in miRNA spectra in urine samples from patients with urothelial conditions indicate the potential for using specific miRNAs as biomarkers for detecting and monitoring various physiopathological conditions. The study also found that miRNAs are present in a wide range of body fluids, with some miRNAs being unique to specific fluids. For example, miR-224 was found in plasma, miR-637 in tears, miR-193b in breast milk, and miR-508-5p in seminal fluid. The miRNA profiles of different body fluids showed some similarities, with plasma and saliva sharing a large number of miRNAs. However, plasma and urine shared the fewest number of commonly detectable miRNAs, suggesting that many circulating miRNAs are either removed by the kidneys or destroyed in the urine. The study also found that miRNAs in tears were highly abundant, suggesting a potential role in maintaining or regulating the normal function of the eyes. The presence of miRNAs in various body fluids, including urine, suggests their potential as biomarkers for detecting and monitoring various physiopathological conditions. The study highlights the importance of miRNAs as potential biomarkers for disease detection and monitoring, as well as their role in cell-cell communication. The findings suggest that miRNAs could be used as non-invasive biomarkers for various diseases, including urothelial cancers.MicroRNAs (miRNAs) are small, non-coding RNA molecules that regulate biological processes by interacting with messenger RNAs. They are present in various body fluids, including serum, plasma, saliva, and urine, and have been associated with pathological conditions such as cancer. This study examined the presence of miRNAs in 12 human body fluids, including urine samples from individuals with different urothelial conditions. Using quantitative PCR, the researchers conducted a global survey of miRNA distribution in these fluids. The results showed that miRNAs were present in all tested fluids and exhibited distinct compositions in different fluid types. Some miRNAs were common among multiple fluid types, while others were enriched in specific fluids. The study also observed distinct miRNA patterns in urine samples from individuals with different physiopathological conditions. The findings suggest that miRNAs are ubiquitous in all tested body fluids and may have functional roles associated with surrounding tissues. The changes in miRNA spectra in urine samples from patients with urothelial conditions indicate the potential for using specific miRNAs as biomarkers for detecting and monitoring various physiopathological conditions. The study also found that miRNAs are present in a wide range of body fluids, with some miRNAs being unique to specific fluids. For example, miR-224 was found in plasma, miR-637 in tears, miR-193b in breast milk, and miR-508-5p in seminal fluid. The miRNA profiles of different body fluids showed some similarities, with plasma and saliva sharing a large number of miRNAs. However, plasma and urine shared the fewest number of commonly detectable miRNAs, suggesting that many circulating miRNAs are either removed by the kidneys or destroyed in the urine. The study also found that miRNAs in tears were highly abundant, suggesting a potential role in maintaining or regulating the normal function of the eyes. The presence of miRNAs in various body fluids, including urine, suggests their potential as biomarkers for detecting and monitoring various physiopathological conditions. The study highlights the importance of miRNAs as potential biomarkers for disease detection and monitoring, as well as their role in cell-cell communication. The findings suggest that miRNAs could be used as non-invasive biomarkers for various diseases, including urothelial cancers.