What Is the Chemical Composition of Urine?

Urine samples
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Urine is a liquid produced by the kidneys to remove waste products from the bloodstream. Human urine is yellowish in color and variable in chemical composition, but here is a list of its primary components.

Primary Components

Human urine consists primarily of water (91% to 96%), with organic solutes including urea, creatinine, uric acid, and trace amounts of enzymes, carbohydrates, hormones, fatty acids, pigments, and mucins, and inorganic ions such as sodium (Na+), potassium (K+), chloride (Cl-), magnesium (Mg2+), calcium (Ca2+), ammonium (NH4+), sulfates (SO42-), and phosphates (e.g., PO43-).

A Representative Chemical Composition of Urine

  • Water (H2O): 95%
  • Urea (H2NCONH2): 9.3 g/l to 23.3 g/l
  • Chloride (Cl-): 1.87 g/l to 8.4 g/l
  • Sodium (Na+): 1.17 g/l to 4.39 g/l
  • Potassium (K+): 0.750 g/l to 2.61 g/l
  • Creatinine (C4H7N3O): 0.670 g/l to 2.15 g/l
  • Inorganic sulfur (S): 0.163 to 1.80 g/l

Lesser amounts of other ions and compounds are present, including hippuric acid, phosphorus, citric acid, glucuronic acid, ammonia, uric acid, and many others. Total solids in urine add up to around 59 grams per person. Note compounds you ordinarily do not find in human urine in appreciable amounts, at least compared with blood plasma, include protein and glucose (typical normal range 0.03 g/l to 0.20 g/l). The presence of significant levels of protein or sugar in urine indicates potential health concerns.

The pH of human urine ranges from 5.5 to 7, averaging around 6.2. The specific gravity ranges from 1.003 to 1.035. Significant deviations in pH or specific gravity may be due to diet, drugs, or urinary disorders.

Table of Urine Chemical Composition

Another table of urine composition in human men lists slightly different values, as well as some additional compounds:

Chemical Concentration in g/100 ml urine
Water 95
Urea 2
Sodium 0.6
Chloride 0.6
Sulfate 0.18
Potassium 0.15
Phosphate 0.12
Creatinine 0.1
Ammonia 0.05
Uric acid 0.03
Calcium 0.015
Magnesium 0.01
Protein --
Glucose --

Chemical Elements in Human Urine

The element abundance depends on diet, health, and hydration level, but human urine consists of approximately:

  • Oxygen (O): 8.25 g/l
  • Nitrogen (N): 8/12 g/l
  • Carbon (C): 6.87 g/l
  • Hydrogen (H): 1.51 g/l

Chemicals That Affect Urine Color

Human urine ranges in color from nearly clear to dark amber, depending largely on the amount of water that is present. A variety of drugs, natural chemicals from foods, and diseases can alter the color. For example, eating beets can turn urine red or pink (harmlessly). Blood in the urine may also turn it red. Green urine may result from drinking highly colored beverages or from a urinary tract infection. Colors of urine definitely indicate chemical differences relative to normal urine but aren't always an indication of illness.

Additional Sources

View Article Sources
  1. Rose, C., A. Parker, B. Jefferson, and E. Cartmell. "The Characterization of Feces and Urine: A Review of the Literature to Inform Advanced Treatment Technology." Critical Reviews in Environmental Science and Technology, vol 45, no. 17, 2015, pp. 1827-1879, doi:10.1080/10643389.2014.1000761

  2. Bökenkamp, Arend. "Proteinuria—take a closer look!" Pediatric Nephrology, 10 Jan. 2020, doi:10.1007/s00467-019-04454-w

  3. Wonhee So, Jared L. Crandon and David P. Nicolau. "Effects of Urine Matrix and pH on the Potency of Delafloxacin and Ciprofloxacin against Urogenic Escherichia coli and Klebsiella pneumoniae." Journal of Urology, vol. 194, no. 2, pp. 563-570, Aug. 2015, doi:10.1016/j.juro.2015.01.094

  4. Perrier, E., Bottin, J., Vecchio, M. et al. "Criterion values for urine-specific gravity and urine color representing adequate water intake in healthy adults." European Journal of Clinical Nutrition, vol. 71, pp. 561–563, 1 Feb. 2017, doi:10.1038/ejcn.2016.269

  5. "Red, brown, green: urine colors and what they might mean. Departures from the familiar yellow are often harmless but should be discussed with a doctor." Harvard Health Letter, 23 Oct. 2018. 

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Helmenstine, Anne Marie, Ph.D. "What Is the Chemical Composition of Urine?" ThoughtCo, Aug. 26, 2020, thoughtco.com/the-chemical-composition-of-urine-603883. Helmenstine, Anne Marie, Ph.D. (2020, August 26). What Is the Chemical Composition of Urine? Retrieved from https://www.thoughtco.com/the-chemical-composition-of-urine-603883 Helmenstine, Anne Marie, Ph.D. "What Is the Chemical Composition of Urine?" ThoughtCo. https://www.thoughtco.com/the-chemical-composition-of-urine-603883 (accessed May 29, 2023).