Medical Term for Excessive Fluid Intake
The medical term for excessive fluid intake is "polydipsia," with the specific subtype "primary polydipsia" referring to excessive drinking not caused by hyperglycemia or renal dysfunction. 1
Key Terminology and Classification
Polydipsia literally means "excessive drinking caused by increased thirst" 1. This umbrella term encompasses several distinct clinical entities:
Types of Primary Polydipsia
- Psychogenic polydipsia (PsyP): Compulsive water drinking associated with psychiatric disorders, particularly chronic schizophrenia, dependency disorders, and depression 2, 3, 4
- Dipsogenic polydipsia (DiP): Habitual excessive drinking without clear psychogenic cause 2
- Beer potomania: Excessive beer consumption leading to hyponatremia 2
Clinical Recognition
When assessing a patient who drinks excessively, look for these specific features:
Volume consumed: Typically 8-12 liters per day in pathologic cases 5, though even lower volumes can cause problems depending on renal function and other factors
Associated findings:
- Polyuria (excessive urine production) accompanies polydipsia 1
- Bedding becomes wetter in hospitalized patients 6
- Water bottles empty more rapidly 6
- Plasma copeptin levels <21.4 pmol/L suggest central diabetes insipidus rather than primary polydipsia 1
Critical Distinction from Other Conditions
Primary polydipsia must be differentiated from:
- Central diabetes insipidus (responds to DDAVP) 1
- Nephrogenic diabetes insipidus (does not respond to water deprivation) 1
- Poorly controlled diabetes mellitus (high urine osmolality with hyperglycemia) 1
The key distinguishing feature: patients with primary polydipsia respond to water deprivation 1, whereas those with diabetes insipidus do not.
Clinical Significance and Outcomes
This is not a benign condition. In a systematic review of 590 patients with water intoxication, 13% died and severe presentations (seizures, coma) occurred in 53% of cases 5. Among patients with profound hyponatremia from polydipsia, 67% were readmitted within one year, with 52% experiencing recurrent hyponatremia 2.
Common precipitating factors include:
- Psychiatric diagnoses (52% of cases) 5
- Iatrogenic causes (13%) - such as excessive water intake advised for urologic procedures 7, 8
- Exercise-related (12%) 5
- No underlying condition in 31% 5
Practical Caveats
Polydipsia is a contraindication to desmopressin treatment 9, as the combination can cause water intoxication with hyponatremia and convulsions. If prescribing desmopressin for any reason, specifically ask about drinking habits and advise limiting evening fluid intake to 200 ml or less 9.
In patients with psychiatric illness presenting with neurological symptoms, maintain high suspicion for excessive water intake, particularly if they exhibit anxiety, fear, or have been advised to "drink lots of water" for any medical reason 7.