###### Abstract
This study identified important factors such as differences in metabolite excretion due to sampling time, gender, and inter- and intra-individual variability, each of which influences the increased use of urine in metabolic and future clinical diagnostic studies. A total of 23 urinary metabolites were quantitatively variable in normal guinea pigs. In total, 24 urinary metabolites were quantitatively variable in healthy subjects. For example, 12 metabolites were found to be statistically different in men and women: 2-hydroxyisobutyrate, 4-aminohippurate, aspartate, citrate, creatine, formate, hippurate, histidine, lactate, threonine, transaconitate, and \(N\)-methylhistidine. The first database of specific urine volatiles (urine volatolome), consisting of 841 compounds of 80 different chemical classes, including cancer-associated substances, was presented in the review [4]. Prostate cancer (PC) is one of the most common male diseases worldwide. Consequently, the proportion of prostate cancer diagnosed at a distant stage increased from 3.9% to 8.2% over the past decade [5]. According to data from World Cancer Research Fund International, prostate cancer is the second most common cancer in men worldwide and the fourth most common cancer overall. There were more than 1.4 million new cases of prostate cancer in 2020 [6]. Zimbabwe had the highest rate of prostate cancer mortality in 2020, followed by Barbados. Haiti, Zambia, Jamaica, Trinidad and Tobago, The Bahamas, Dominican Republic, Saint Lucia, and Cote d'Ivoire are also among the 10 countries with high prostate cancer mortality. The most commonly used serum marker of cancer is prostate-specific antigen (PSA), which is an androgen-controlled serine protease produced by both prostate epithelial cells and prostate cancer (PC). PSA is secreted into the prostate ducts as an inactive 244 amino acid proenzyme (proPSA), which is activated by cleavage of seven \(N\)-terminal amino acids. The PSA that enters blood circulation unchanged is rapidly bound by protease inhibitors, primarily alpha1-antchymotrypsin, although some fraction is inactivated in lumen by proteolysis and circulates as free PSA [7]. Currently, the main methods of PC detection are the determination of PSA levels in blood, digital rectal examination of the prostate, ultrasound and also magnetic resonance imaging, and, if cancer is suspected, biopsy of the prostate. Unfortunately, none of the methods provides a 100% guarantee of diagnosing the presence or absence of a cancerous tumor. In addition to the blood, the PSA secreted from the prostate gland, enters the urine. In [8], where more than 400 samples for serum and urinary PSA levels were analyzed, urinary PSA was found to have a higher predictive ability in differentiating aggressive prostate cancer and may serve as a better surrogate tumor biomarker for detecting aggressive prostate cancer. Also, the combination of PSA ratios of serum and urine enhanced the efficacy of both biomarkers in predicting aggressive prostate diseases. In addition to PSA tests in urine, other urine metabolites were studied to identify PC markers that allow detection of the disease at earlier stages. In [9], based on the statistical analysis of the data obtained by 1H-nuclear-magnetic resonance (1H-NMR) studies of urine samples of 50 patients with PC and 50 volunteers from a control group, 20 detected metabolites were revealed as candidate biomarkers for prostate cancer. Sets of 7-9 metabolites, where a set of 7 metabolites (guanidineacetate, betaine, phenylacetylglycine, taurine, dimethylglycine, \(L\)-alanine, and \(L\)-lactate), 8 metabolites (guanidineacetate, \(L\)-alanine, phenylacetylglycine, \(L\)-lactate, glycine, acetate, dimethylglycine, and formate), and 9 metabolites (guanidineacetate, \(L\)-alanine, phenylacetylglycine, acetate, \(L\)-lactate, glycine, dimethylglycine, formate, and trimethylamine) were identified by three types of statistical analysis. It is proposed to consider guanidineacetate, phenylacetylglycine, and glycine as markers for PC.