What components are normally present in urine?

Normal urine is a complex aqueous solution composed primarily of water (approximately 95%), with the remaining 5% consisting of dissolved solutes. The major constituents include urea—the primary nitrogenous waste product of protein metabolism—along with creatinine, uric acid, and various electrolytes such as sodium, potassium, chloride, phosphate, sulfate, and ammonium ions. Small amounts of organic compounds like hippuric acid, oxalate, and trace proteins (typically <150 mg/day) may also be present. Glucose, ketones, bilirubin, hemoglobin, and nitrites are normally absent or present only in negligible, clinically insignificant quantities. The precise composition varies depending on hydration status, dietary intake, renal function, acid-base balance, and hormonal regulation (e.g., antidiuretic hormone, aldosterone, parathyroid hormone). Urine pH typically ranges from 4.5 to 8.0, with an average of around 6.0, reflecting the body’s efforts to maintain systemic acid-base homeostasis.