Which are the main components of urine?

Water accounts for about 91-96% of urine. The remaining 5% consists of electrolytes, solutes derived from cellular metabolism and exogenous substances such as drugs. Typical normal solutes in urine are: filtered and secreted electrolytes that are not reabsorbed, urea (from protein breakdown), creatinine (from breakdown of creatine phosphate to muscle fibers), uric acid (from breakdown of nucleic acids), urobilinogen (from breakdown of hemoglobin) and small amounts of other substances such as fatty acids, pigments, enzymes and hormones. If a disease alters the body’s metabolism or kidney function, substances may appear that are not normally present in the urine¹.

Also, we can analyze urine samples with the fingerprints of the metabolism; the metabolites. They are low molecular weight compounds derived from metabolic reactions, by which we can extract conclusions about the state of the sample.

The Urine Life Fluids Metabolites Database is ordered by amount of sources at which the compound is found. Giving more relevance to the most found ones, and also more weight to the compounds found in previous databases. The first lines of the metabolites database are shown in Figure 1.

In proteins case, the major compounds of The Urine Life Fluids Protein Database are shown in Figure 2. With a total of 10 different sources of information, we have: Beta-2-glycoprotein 1 (beta2GPI), Insulin-like growth factor-binding protein 7 (IGFBP7), Ceruloplasmin (CP), Cystatin-C, and Neutrophil gelatinase-associated lipocalin (NGAL).

Finally, in metals case, a total of 76 metals could be detected in urine samples from which 62 of them are metals, 7 metalloids, and 7 non-metals. They are all gathered in The Urine Life Fluids Metals Database. The first rows are shown in Figure 3.

Bibliography

1. Tortora GJ, Bryan D. Principios de anatomía y fisiología, 13va Edición. 13th ed. Editorial Medica Panamericana Sa, editor. México D.F.: Editorial Medica Panamericana Sa; 2013. 1067–1099 p.