Urine is an amber-colored solution produced by the filtration activity of the kidney, an organ perennially committed to maintaining constant volume, osmolarity and pH of the blood, and to balancing the concentrations of the various solutes that circulate within it.
Under normal conditions, water represents about 95% by weight of urine; in the remaining fraction, a leading role is played by urea (2-2.5%), nitrogen (1-1.5%) and sodium chloride (1-1.5%). In the urine you can also find mineral salts (such as sodium, calcium, potassium and magnesium), uric acid, bile pigments, ammonia, any drug metabolites and many other substances. On the other hand (except for underlying pathologies) significant concentrations of glucose are not found. (diabetes), pus and bacteria (kidney and / or urinary tract infections), acetone (prolonged fasting or diabetes), protein / albumin (diabetic nephropathy, kidney failure) and blood (stones, neoplasms or inflammation of the kidney or of the urinary tract).
Compared to the nearly 200 liters of plasma filtered daily by the kidney, the amount of urine produced by an adult man is around one and a half liters per day, with wide variations based on the state of hydration. From the kidney, urine flows into the renal pelvis, then into the ureter which conveys it into the bladder, a hollow organ responsible for its accumulation. The bladder has a capacity of about 500 ml and when needed it is emptied in an act, called urination, in which urine is emitted to the outside through the urethra.
In-depth articles on urine
- Urine color: normally yellowish, clear and of a shade similar to that of beer. Numerous conditions, pathological or not, can alter these chromatic characteristics, giving the urine an unusual appearance.
- Urine odor: normally "sui generis" and as such devoid of bad fragrances. A foul-smelling urine can therefore be a sign of pathological conditions, but not necessarily.
- Smelly urine: they can be the non-worrying consequence of the ingestion of particular foods, a sign of dehydration (and in this case the complexion is particularly dark) or the consequence of urinary tract infections, such as urethritis and cystitis, or genital (prostatitis) .
- Blood in the urine: when the pink color is not determined by the intake of particular drugs or foods, it is often linked to the presence of stones, neoplasms or inflammation in the kidney or urinary tract.
- Hemoglobin in the urine: it is similar but different to the previous condition, as it is often caused by the destruction of red blood cells within the bloodstream, with the passage of hemoglobin, normally absent, in the expelled urine.
- Foam in the urine: the occasional presence of foam in the urine should not worry (especially if the toilet has just been cleaned). Small and persistent bubbles, similar to those of beer, can however be caused by various diseases affecting, above all, the kidney.
- Leukocytes in the urine: Indicator of a probable urinary tract infection. This condition can be signaled by the cloudy appearance of the urine, due to the presence, not only of leukocytes, but also of mucus, pus, blood and flaking cells.
- Yellow urine and vitamins: After taking a vitamin supplement, most people notice that their urine turns a deep yellow, almost fluorescent.
- urine pH: it can vary within a rather wide range of normality in relation to the diet and the health of the organism. Outside of certain limits, the condition is considered pathological.
- Urinary sediment: it is given by the set of microscopic debris, cellular and otherwise, which, in relation to the patient's state of health, can be found in the urine in variable concentrations.
- Urinary infections: causes, symptoms, treatment and prevention.
- Frequent urination: identified by the medical term pollakiuria, it consists of an increase in the daily episodes of expulsion of urine.
- Dysuria: general difficulty in urinating. Dysuria is a typical symptom of affections of the urinary tract, but also of genital (for example, prostatic hypertrophy).
- Stranguria: painful and slow passing of urine.
- Bladder tenesmus: painful sensation of urgent need to urinate, which is accompanied by a reduced emission of urine, with a sense of incomplete emptying of the bladder.
- Polyuria: Production of large amounts of urine, which appears clear and diluted.
- Oliguria: decreased excretion of urine, usually understood to be less than 400 ml / day in the average-sized adult.
- Anuria: decrease in diuresis below 100 ml / day.
- Urinary incontinence: a condition that affects about 30% of women and is characterized by the involuntary loss of urine in socially inappropriate moments and places.
- Nocturia: the need to urinate during the night's rest, not justified by a large intake of liquids.
- Protein in urine: This condition, known as proteinuria, is linked to kidney problems often caused by diabetes or hypertension.
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