Potomania (From Greek pōtō "drink (liquor)" + mania) is a specific hypo-osmolality syndrome related to massive consumption of beer, which is poor in solutes and electrolytes. With little food or other sources of electrolytes, consumption of large amounts of beer or other dilute alcoholic beverages leads to electrolyte disturbances, where the body does not have enough nutrients known as electrolytes, namely sodium, potassium, and magnesium. The symptoms of potomania are similar to other causes of hyponatremia and include dizziness, muscular weakness, neurological impairment and seizures, all related to hyponatremia and hypokalaemia. While the symptoms of potomania are similar to other causes of hyponatremia and acute water intoxication, it should be considered an independent clinical entity because of its often chronic nature of onset, pathophysiology, and presentation of symptoms.

The normal human kidney, through suppression of anti-diuretic hormone, is able to excrete vast amounts of dilute urine. Healthy adult kidneys are able to excrete over 20 liters of water each day. However, maximum hourly rates rarely exceed 800 to 1,000 mL/hr. The intake of solutes is necessary to excrete free water. Under normal circumstances, this is clinically irrelevant. In the lack of proper solute intake, the amount of free water excretion can be severely limited. Without adequate solute intake, the normal functioning electrolyte gradient that pulls water into urine will be effectively destroyed.

To excrete water the kidney must also excrete solute. Solute presented to the kidney is derived from the diet in the form of electrolytes such as sodium, chloride and potassium. The other main solute is blood urea nitrogen which is created from protein metabolism. The kidney is able to excrete urine with a broad range of osmolalities - roughly 40 to 1200mOsmol/kg. It cannot excrete urine that is more dilute than 40mOsmol/kg. A normal diet provides a renal solute load of approximately 600mOsmol/kg. An individual with a normal diet can therefore excrete up to 15L of water per day (600/40). If a person has a very poor dietary intake of electrolytes and either eats very little protein (and/or inhibits protein metabolism by the intake of carbohydrate) - which is very characteristic of alcoholics - then the renal solute load may fall below a level that is sufficient to clear the volume of water ingested. Although beer has a relatively high osmolality due to the ethanol concentration (standard beer osmolality is roughly 1000mOsmol/kg) it provides little renal solute contribution and is low in sodium. If the dietary/renal solute load is less than the volume of water ingested (in litres divided by 40) then the excess free water will be retained leading to dilutional hyponatremia. For example if the renal solute load is 200 the maximum water able to be excreted per 24 hours is 5L. If the person drinks 6L of beer then 1L per day will be retained as free water.

Any vomiting or GI absorptive problems due to alcohol intoxication can also compound the effect of potomania due to additional electrolyte and acid-base disturbances.

The diagnosis of potomania requires both clinical and biochemical criteria.

Hypotonic hyponatremia

Dilute urine (< 100mOsmol/kg) although this finding is variable in the few cases described in the medical literature

Clinical evidence of excessive beer (or equivalent alcoholic drinks such as cider) consumption often accompanied by evidence of poor dietary intake.