Polyuria resident survival guide

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Overview

  • Polyuria is defined as urine output more than 2 L/24 hours, or 30 ml/kg/24 hours. There are 3 pathophysiologic causes of polyuria: increased thirst (idiopathic, psychogenic polydepsia, hypothalamic disease, and medications), central diabetes insipidus (DI) (decreased secretion of arginine vasopressin (AVP)), and nephrogenic diabetes insipidus (DI) (renal resistance to AVP).[1]
  • Nocturnal polyuria (NP), characterized by overproduction of urine at night (more than 20%-33% of total 24-hour urine volume depending on age). It can be caused by intake, urological, nephrological, hormonal, sleep, and cardiovascular factors. [2]

Causes

Life threatening causes

Common causes

The most common causes of polyuria are: psychogenic polydipsia, diabetes insipidus (central and nephrogenic), chronic kidney disease and uncontrolled diabetes mellitus. [3]

Diagnosis

Approach to polyuria

 
 
 
 
 
 
 
Polyuria
❑ 24-hour urine volume >3L
❑ 24-hour urine volume >50 ml/kg
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Urine Osmolality >300mosmol
 
 
 
 
 
 
 
Urine Osmolality <300[4]mosmol
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Solute diuresis
Glucose
Mannitol
Contrast media
High protein intake
Diuretics
Medullary cystic disease
Resolving ATN
Resolving obstruction
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Water diuresis
Primary polydipsia
Diabetes inspidous
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Water restriction test OR administration of hypertonic saline 0.05 mL/kg/min for 2 h
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Water restriction test
❑ Overnight fluid restriction should be avoided
❑ Recommend the patient to stop drinking 2-3 hours before coming to clinic
❑ Meaure urine volume every hour
❑ Measure urine osmolality every hour
❑ Measure plasma sodium concentration every 2 hours
❑ Measure plasma osmolality every 2 hours
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Test endpoints in adults:
❑ Urine osmolality reaches normal value (above 600 mosmol/kg)
❑ The urine osmolality is stable for 2 or 3 successive hourly measurements despite a rising plasma osmolality
❑ Plasma osmolality >295-300 mosmol/kg
❑ Plasma sodium is 145 or higher

Treatment

Cranial diabetes insipidus:

  • Cranial diabetes insipidus (DI) can be managed by desmopressin orally or Intranasal (rarely used).
  • Partial DI can be treated with a single nocturnal dose to prevent sleep loss due to nocturia, but complete DI requires 2-4 daily doses.

Nephrogenic diabetes insipidus:

  • Withdrawal of lithium therapy usually leads to reversal of lithium-induced diabetes insipid (DI). It can persist for years after lithium withdrawal, usually indicating that the patient has developed interstitial nephritis secondary to lithium.
  • Thiazide diuretics reduce urine output by up to 50%, and indomethacin has also been used. Results are frequently unsatisfactory, treatment is directed at sufficient fluid intake to replace urinary losses. [1]

Do's

Don'ts

References

  1. 1.0 1.1 Moore K, Thompson C, Trainer P (2003). "Disorders of water balance". Clin Med (Lond). 3 (1): 28–33. doi:10.7861/clinmedicine.3-1-28. PMC 4953350. PMID 12617410.
  2. Weiss JP, Everaert K (2019). "Management of Nocturia and Nocturnal Polyuria". Urology. 133S: 24–33. doi:10.1016/j.urology.2019.09.022. PMID 31586470.
  3. Wieliczko M, Matuszkiewicz-Rowińska J (2013). "[Polyuria]". Wiad Lek. 66 (4): 324–8. PMID 24490488.
  4. Robertson GL: Diabetes insipidus. Endocrinol Metab Clin North Am 24:549–572, 1995.