Water Intoxication


Water Intoxication, Water Toxicity, Psychogenic Polydipsia, Tea and Toast Syndrome, Beer Potomania Syndrome

  • Pathophysiology
  1. Water Intoxication, beer potomania, Tea and Toast Syndrome share a similar mechanism for Hyponatremia
    1. Patient with excessive hypoosmolar fluid intake (free water, beer, tea) and low solute diet (low Sodium intake)
    2. Intake exceeds the renal capacity for free water excretion (50 to 100 meq/L or mOsm/L, specific gravity <1.003)
  2. Example: Normal Patient
    1. Patient ingests 600 mOsms solute (e.g. salt, Potassium) per day (10 mOsm/kg/day for a 60 kg person)
    2. If urine most dilute at 50 mEq/L, they could excrete 12 liters worth of free fluid intake without Hyponatremia
    3. However, renal excretion of dilute urine would be overwhelmed at 13 liter intake, and Hyponatremia would begin
  3. Example: Low solute intake (e.g. beer potomania, Tea and Toast Syndrome)
    1. Patient ingests only 100 mOsms solute per day (the remainder is beer, tea)
    2. Renal excretion of dilute urine is overwhelmed at only 2 Liters/day
  4. Example: Exercise Associated Hyponatremia
    1. Extrarenal Solute Losses Replaced with Free Fluid
    2. Excessive extrarenal losses (e.g. sweating) replaced with large volume of free fluid intake
  • Causes
  1. See Exercise Associated Hyponatremia
  2. Water Intoxication (Psychogenic Polydipsia)
    1. Free water intake exceeds free water excretion
    2. Seen in Psychosis (Schizophrenia, Bipolar Disorder)
  3. Beer Potomania Syndrome
    1. Excessive Alcohol intake (esp. beer) and low solute dietary intake
  4. Tea and Toast Syndrome (esp. elderly)
    1. Diet lacking in salt and Protein but with excessive oral free water intake
    2. Compounded by the typically low Glomerular Filtration Rate (GFR) in the elderly (increases fluid reabsorption)
  5. Hypotonic Saline infusion
    1. Affects 4-5% of post-operative patients
  6. Methylenedioxymethamphetamine (MDMA, Ecstasy, Molly)
    1. May result in Water Intoxication to point of severe Hyponatremia (deaths have occurred)
  • Findings
  • Labs
  1. See Isovolemic Hypoosmolar Hyponatremia
  2. See Hyponatremia
  3. Diagnosis
    1. Hyponatremia
    2. Hypoosmolality
    3. Normal extracellular fluid (normovolemic)
    4. Urine Sodium < 10 (Urine Osmolality <100 mOsm/kg, maximally dilute urine)
  • Differential Diagnosis
  • References
  1. Glaser (2022) EM:Rap 22(6): 9-11
  2. Peechakara (2022) Water Toxicity, StatPearls, Treasure Island, accessed online 6/2/2022
  3. Lodhi (2017) Cureus 9(12): e2000 [PubMed]
  4. Miller (2023) Am Fam Physician 108(5): 476-86 [PubMed]