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Volume of the Urine
بقول ابن سینا: مقدارالبول
Urinary Tract Conditions that Effect the Urine Volume
Decreased force of urination: “It usually secondary to bladder outlet obstruction and commonly results from benign prostatic hyperplasia (BPH) or a urethral stricture.”
Urinary frequency: “It is due to either increased urinary output (polyuria) or decreased bladder capacity in certain diseases. The normal adult voids 4 to 6 times per day, with a volume of approximately 300 to 500 ml with each void. Frequency during the day without nocturia is usually of psychogenic origin and related to anxiety. Nocturia without frequency may occur in the patient with congestive heart failure and peripheral edema in whom the intravascular volume and urine output increase when the patient is supine. Renal concentrating ability decreases with the age; therefore urine production in the geriatric patient is increased at night when renal blood flow is increased as a result of recumbency.”
Urinary hesitancy: “It refers to a delay in the start of micturition. Normally, urination begins within a second after relaxing the urinary sphincter, but it may be delayed in men with bladder outlet obstruction.”
Intermittency: “It refers to involuntary start-stopping of the urinary stream. Most commonly it results from prostatic obstruction with intermittent occlusion of the urinary stream by lateral prostatic lobes.”
Urinary incontinence: “It is the involuntary loss of urine, some medical experts suggest that it present only when a patient thinks it is a problem. The disorder is greatly under-recognized and under reported. With aging, bladder capacity decreases, the ability to inhibit urination declines, involuntary bladder contractions (detrusor overactivity) occur more often, and bladder contractility impaired. Thus, the voiding becomes more difficult to postpone and tends to be incomplete. Pelvic muscle exercises (eg, Kegel exercises) are often effective, especially for stress incontinence.”
Postvoid dribbling: “It refers to the terminal release of drops of urine at the end of micturition. This is secondary to a small amount of residual urine either in the bulbar or in the prostatic urethra that is normally “milked back” into the bladder at the end of micturition. In men with bladder outlet obstruction, this urine escapes into bulbar urethra and leaks out at the end of micturition.”
Note: “Men frequently attempt to avoid wetting their clothing by shaking the penis at the end of micturition. In fact, this is ineffective, and the problem is more readily solved by the manual compression of the bulbar urethra in the perineum and blotting the urethral meatus with a tissue paper. Postvoid dribbling is often an early symptom of urethral obstruction related to BPH, but, in itself, seldom necessitates any further treatment in the modern medicine.”
Straining: “It refers to the use of abdominal musculature to urinate. Increased straining during micturation is a symptom of bladder outlet obstruction.”
According to the Modern Medicine
“The average adult cardiac output is about 5 liters per minute and about 25% of that is received by the kidneys per minute. About 99% of the filtered fluid circulating through the kidneys is reabsorbed into the blood with the remaining only 1% excreted as urine. Approximately 1000 liters of the blood filtered through the kidneys produce one liter of urine. Urine is normally 95% water and 5% solutes, although considerable variations in the concentrations of these solutes can occur owing to the influence of factors such as dietary intake, physical activity, body metabolism, endocrine functions, and even body position. Volume of urine for a healthy adult is about 750 to 2500 mL or (800 to 2000 ml) of urine in 24 hours, or approximately 25 to 30 ml per hour”.
Children’s output varies by age and body weight.
Infants and toddlers: 2-3 mL/kg/hr.
Preschool and young school age: 1-2 mL/kg/hr.
School age and adolescents: 0.5-1 mL/kg/hr.
Disorders that cause decreased urine output: “Reduced water intake, hot weather, prerenal perfu-sion impairment due to dehydration, low blood pressure, congestive heart failure, edema, cirrhosis, peritonitis, nephrotic syndrome, or end-stage renal disease (Consistency will be low).”
Disorders that cause increased urine output: “Diabetes insipidus: central or nephrogenic, Diabetes mellitus (there will also be a high specific gravity or Consistency), excess protein, excess sodium in the diet, chronic renal failure, polydipsia and intake of corticosteroids, diuretics or caffeine.”
Polyuria caused by water diuresis: “It results from decreased tubular reabsorption of water in distal part of the nephrons. Physiologically it can be as a result of high water intake and pathologically as due to impaired secretion of an Antidiuretic Hormone (ADH) (as in diabetes insipidus).”
Polyuria caused by osmotic diuresis: “It results from either increased filtration of osmotically active substances due to their high concentration in the ECT (e.g. hyperglycemia), or from their decreased tubular reabsorption. The osmotic diuresis is characteristic e.g. for diabetes mellitus (glucosuria), the polyuric phase of renal failure, or comes as an effect of diuretic drugs.”The general rule is “high urine volume with low specific gravity are often, evidence of kidney disease” and “low urine volume with high specific gravity can result from a faulty water supply”.
Affected Organs: Kidneys, pancreas, pituitary, hypothalamus, heart, liver.
Suggested Readings
- Zuidema, G. D., Clarke, N. P., Reeves, J. L., Gauer, O. H., & Henry, J. P. (1956). Influence of moderate changes in blood volume on urine flow. American Journal of Physiology-Legacy Content, 186(1), 89-91.
- Vulliamy, D. (1956). The day and night output of urine in enuresis. Archives of disease in childhood, 31(160), 439.
- Avicenna’s Canon of medicine by O. C. Gruner.
Tag:Urology in Canon