Urine Composition

Urine is a waste product of the body, primarily used to excrete toxins and balance water and electrolytes.
Normal urine is primarily composed of water, making up approximately 95% of its volume.
The other 5% consists of solutes, largely organic and inorganic substances.

Major Components of Urine

The remaining components, apart from water, include urea, uric acid, and creatinine.
Urea is the main excretory product of protein metabolism. It is the largest solute component of urine by mass.
Uric acid is the end product of purine metabolism. Purines are components of nucleic acids.
Creatinine is produced as a waste product of creatine, an energy reserve for muscles.

Electrolytes in Urine

In addition to these, various electrolytes such as sodium, potassium, and chloride are also present in urine.
The concentration of these electrolytes varies depending on dietary intake and body regulation mechanisms.

Abnormal Urine Composition

Substances not usually found in the urine, or found at elevated levels, can indicate a disease state.
Examples include glucose (indicative of diabetes) and red and white blood cells (indicative of infection or kidney disease).
The presence of proteins in urine, a condition called proteinuria, may indicate kidney damage.

Urine composition provides valuable insight into the body’s metabolic functioning and the state of an individual’s health. Changes from normal urinary constituents can signify pathological conditions demanding medical attention. The study of urine composition, or urinalysis, is a common diagnostic tool in biomedical science.