Urine is an amber colored solution produced by the kidney filtration activity, an organ perpetually committed to maintaining a constant volume, osmolarity and pH of the blood, and to balance the concentrations of the various solutes circulating inside it.

The excesses are compensated for by increasing the phenomena of excretion with the urine, while the deficiencies are filled by reabsorbing what has been filtered and consequently reducing the urinary elimination. For this reason, the qualitative and quantitative composition of urine provides information on many physiological and pathological processes that occur in the body.

Under normal conditions, water represents about 95% by weight of urine; in the remaining fraction, a major role is covered by urea (2-2.5%), nitrogen (1-1.5%) and sodium chloride (1-1.5%). Mineral salts (such as sodium, calcium, potassium and magnesium), uric acid, bile pigments, ammonia, any drug metabolites and many other substances can also be found in the urine. However, significant concentrations of glucose (diabetes), pus and bacteria (infections of the kidney and / or urinary tract), acetone (prolonged fasting or diabetes), proteins / albumin (diabetic nephropathy, kidney failure) are not found (except for pathologies). and blood (stones, neoplasms or inflammations in the kidney or urinary tract).

Against the almost 200 liters of plasma filtered daily by the kidney, the amount of urine produced by an adult man is around a liter and a half a day, with wide variations depending on the state of hydration. From the kidney, urine flows into the renal pelvis, then into the ureter that conveys it into the bladder, a hollow organ for its accumulation. The bladder has a capacity of about 500 ml and when needed is emptied into an act, called urination, in which urine is emitted 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 otherwise, can alter these chromatic characteristics, giving the urine an unusual appearance.
  • Odor of urine: normally "sui generis" and as such lacking in bad fragrances. Smelly urine can therefore be a sign of pathological conditions, but not necessarily.
  • Foul-smelling urine: may be the non-worrying consequence of ingesting particular foods, a signal 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 pinkish color is not determined by the use of particular drugs or foods, it is often linked to the presence of calculi, neoplasms or inflammations in the kidney or urinary tract.
  • Hemoglobin in the urine: it is similar but different to the previous condition, since it is often caused by the destruction of the red blood cells inside the blood circulation, with the passage of hemoglobin, normally absent, in the expelled urine.
  • Foam in urine: the occasional presence of foam in the urine should not worry (especially if the toilet has just been cleaned). However, small and persistent bubbles, similar to those of beer, can be caused by various pathologies affecting, above all, the kidney.
  • Urine leukocytes: a sign of a probable urinary tract infection. This condition can be signaled by the turbid 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 an intense yellow, almost fluorescent.
  • pH of urine: 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: is given by the set of microscopic debris, both cellular and non-cellular, which in relation to the patient's state of health can be found in urine in varying concentrations.
  • Urinary infections: causes, symptoms, treatment and prevention.
  • Frequent urination: identified by the medical term pollakiuria, consists in the increase of daily episodes of urine expulsion.
  • Dysuria: general difficulty in urinating. Dysuria is a typical symptom of diseases of the urinary tract, but also genital (for example of prostatic hypertrophy).
  • Stranguria: painful and slow emission of urine.
  • Bladder tenesmus: painful sensation of urgent need for urination, 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 urine excretion, usually referred to as less than 400 ml / day in middle-aged adults.
  • 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: need to urinate during night 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.