A4. Symptoms related to the act of urination and quantitative changes of the urine

Lower urinary tract symptoms

Lower urinary tract symptoms (LUTS) refers to symptoms related to the act of urination. They include voiding symptoms and storage symptoms. LUTS are classically caused by benign prostatic hyperplasia. Treatment of the underlying cause alleviates the symptoms.

Etiology

• BPH (most common)
• Lower urinary tract infection

Clinical features

We distinguish two types of LUTS, voiding symptoms (also called obstructive symptoms), and storage symptoms (also called irritative symptoms).

• Storage/irritative symptoms – symptoms related to abnormal bladder function
  • Urinary frequency – more than 8x a day
  • Urinary urgency – strong feeling of needing to void
  • Nocturia = the need to wake up multiple times in the night to urinate
    • Heart failure
  • Urinary incontinence
• Voiding/obstructive symptoms – symptoms related to abnormal voiding
  • Hesitancy – delayed initiation of micturition
  • Need for straining to urinate – patient must contract abdominal muscle to urinate
  • Intermittent, not continuous, urine stream
  • Terminal dribbling of urine
  • Sensation of incomplete voiding

Quantitative changes of the urine

One normally produces 500 - 2500 mL of urine per day. In case of pathology, the amount may be increased or decreased.

Polyuria refers to pathologically increased amount of urine (> 2500 mL/day) or > 50 mL per kg of bodyweight per hour. It's a relatively rare finding.

Oliguria refers to decreased amount of urine (100 - 500 mL/day) or < 20 mL/hour or < 0.5 mL per kg of bodyweight per hour.

Anuria refers to having < 100 mL of urine during a day.

Causes

• Polyuria
  • Diabetes insipidus
  • Diabetes mellitus
  • Diuretics
  • Primary polydipsia (psychogenic)
• Oliguria
  • Due to acute kidney injury
  • Prerenal causes
    • Dehydration
    • Heart failure
    • Renal artery stenosis
  • Intrarenal causes
    • Acute tubular necrosis
    • Acute or chronic glomerulonephritis
    • Acute interstitial nephritis
  • Postrenal causes
    • Obstruction
• Anuria
  • Generally same as for anuria, but more severe