(ū′rĭn)
[Pronunciation]
[L. urina; Gr. ouron, urine]

The fluid and dissolved solutes (including salts and nitrogen-containing waste products) that are eliminated from the body by the kidneys.


Significance of Changes in Urine

QUANTITY
Normal	Abnormal	Significance
1000–3000 ml/day		Varies with fluid intake, food consumed, exercise, temperature, kidney function
	High (polyuria >3000 ml/day)	Diabetes insipidus, diabetes mellitus, water intoxication, chronic nephritis, diuretic use
	Low (oliguria)	Dehydration, hemorrhage, diarrhea, vomiting, urinary obstruction, or many intrinsic kidney diseases
	None (anuria)	Same as oliguria
COLOR
Normal	Abnormal	Significance
Yellow to amber		Depends on concentration of urochrome pigment
	Pale	Dilute urine, diuretic effect
	Milky	Fat globules, pus, crystals
	Red	Drugs, blood or muscle pigments
	Green	Bile pigment (jaundiced patient)
	Brown-black	Toxins, hemorrhage, drugs, metabolites
HEMATURIA (blood in urine)
Normal	Abnormal	Significance
0–2 RBC/high-powered field (hpf)		Normal (physiological) filtration
	3 or more RBCs/hpf	Extrarenal: urinary tract infections, cancers, or stones. Renal: infections, trauma, malignancies, glomerulopathies, polycystic kidneys
PYURIA (leukocytes in urine)
Normal	Abnormal	Significance
0–9 leukocytes per hpf
	10 or more leukocytes/hpf	Urinary tract infection, urethritis, vaginitis, urethral syndrome, pyelonephritis, and others
PROTEINURIA
Normal	Abnormal	Significance
10–150 mg/day
	30–300 mg/day of albumin	Indicative of initial glomerular leakage in diabetes mellitus or hypertension (microalbuminuria)
	>300 mg/day	Macroalbuminuria. Indicative of progressive kidney failure. Injury to glomeruli or tubulointerstitium of kidney.
	>3500 mg/day	Nephrotic range proteinuria. Evaluation may include kidney biopsy.
SPECIFIC GRAVITY
Normal	Abnormal	Significance
1.010–1.025		Varies with hydration
	1.010 (Low)	Excessive fluid intake, impaired kidney concentrating ability
	>1.025 (High)	Dehydration, hemorrhage, salt-wasting, diabetes mellitus, and others
ACIDITY
Normal	Abnormal	Significance
Acid (slight)		Diet of acid-forming foods (meats, eggs, prunes, wheat) overbalances the base-forming foods (vegetables and fruits)
	High acidity	Acidosis, diabetes mellitus, many pathological disorders (fevers, starvation)
	Alkaline	Vegetarian diet changes urea into ammonium carbonate; infection or ingestion of alkaline compounds

Common Disorders of Urination

Anuria	Complete (or nearly complete) absence of urination
Diversion	Drainage of urine through a surgically constructed passage (e.g., a ureterostomy or ileal conduit)
Dysuria	Painful or difficult urination (e.g., in urethritis, urethral stricture, urinary tract infection, prostatic hyperplasia, or bladder atony)
Enuresis	Involuntary discharge of urine, esp. by children at night (bedwetting)
Incontinence	Loss of control over urination from any cause (e.g., from involuntary relaxation of urinary sphincter muscles or overflow from a full or paralyzed bladder)
Nocturia	Excessive urination at night
Oliguria	Decreased urinary output (usually less than 500 ml/day), often associated with dehydration, shock, hemorrhage, acute renal failure, or other conditions in which renal perfusion or renal output are impaired
Polyuria	Increased urinary output (usually more than 3000 ml/day), such as occurs in diabetes mellitus, diabetes insipidus, and diuresis

COMPOSITION
Urine consists of approx. 95% water and 5% solids. Solids amount to 30 to 70 g/L and include the following (values are in grams per 24 hr unless otherwise noted): Organic substances: urea (10 to 30), uric acid (0.8 to 1.0), creatine (10 to 40 mg/24 hr in men and 10 to 270 mg/24 hr in women), creatinine (15 to 25 mg/kg of body weight per day), ammonia (0.5 to 1.3). Inorganic substances: chlorides (110 to 250 nmol/L depending on chloride intake), calcium (0.1 to 0.2), magnesium (3 to 5 nmol/24 hr), phosphorus (0.4 to 1.3). Osmolarity: 0.1 to 2.5 mOsm/L.

In addition to the foregoing, many other substances may be present depending on the diet and state of health of the individual. Among component substances indicating pathological states are abnormal amounts of albumin, glucose, ketone bodies, blood, pus, casts, and bacteria.

Figure: URINE
(A) white blood cells, (B) squamous epithelial cells, (C) granular cast and uric crystals, (D) fat body (×400)

Subentries:
double-voided urine
midstream specimen of urine
residual urine