Urins

Urins, commonly called urine, is the liquid waste produced by the kidneys. It forms as water and dissolved substances are filtered from blood plasma in the nephrons and modified by tubular reabsorption and secretion. The kidneys regulate fluid balance, electrolytes, and acid-base status, with urine exiting via the ureters, bladder, and urethra.

Composition and variation: Urine is mostly water, with urea, creatinine, uric acid, electrolytes, and other waste products. Daily volume is typically 1–2 liters, depending on hydration and diet. Normal color ranges from pale yellow to amber; pH generally 4.5–8.0, influenced by diet and metabolic state.

Collection and testing: Urinalysis includes visual assessment, dipstick tests, and microscopic examination. In some cases a 24-hour collection or urine culture is used to investigate kidney function or infection.

Clinical relevance: Abnormal findings may indicate disease. Proteinuria, glycosuria, or ketonuria can reflect kidney or metabolic disorders. Hematuria or bacteriuria may signal infection, stones, or trauma. Drugs and foods can alter color and odor.

Notes: Urine is sterile in the bladder but can be contaminated during collection. Proper collection and handling are important for accurate testing.