Beer potomania

Editor-in-Chief: Suresh Samson, M.D., Yale Bridgeport Hospital

Overview
Beer potomania is defined as the development of hyponatremia or low levels of salt in the bloodstream, as a result of excess beer intake coupled with poor nutritional intake. This is a syndrome of binge drinking, poor nutritional intake, and profound hyponatremia.

Pathophysiology & Etiology
Hyponatremia is due to a large consumption of beer (which has a poor salt content) together with a minimal intake of ordinary food. Three facts contribute to beer potomania:
 * 1) Beer contains a lot of free water with very little salt and protein (one liter of beer contains only 30 mg of sodium).
 * 2) The amount of free water we excrete depends upon number of osmoles that need to be excreted.
 * 3) The kidneys can dilute urine to a maximum of 50 mosm/L

The pathophysiologic mechanism of beer potomania can be understood through an example. Imagine someone who binged on 4 liters of beer (which essentially means 4 liters of water) with ingestion of roughly 200 mosm that day. To place this in context, a normal American diet contains 750 mosm/day, and all of it is excreted in urine to maintain a steady state. As a result of the ingestion of this large amount of beer (i.e.free water), the patient's anti diuretic hormone(ADH) (the hormone that causes the kidney to reabsorb free water) secretion is at its minimum to allow the kidneys to excrete maximally dilute urine. Since the maximal dilution that can be attained is 50mosm/L, the kidneys will excrete all the 200 mosm in the diet in 4 litres of urine (50mosm/L X 4L = 200 mosm). This will indeed maintain his sodium level.If this person in our example drinks his 5th litre of beer without taking any further osmoles, then he will become hyponatremic. This is beer potomania

Differential Diagnosis
See the differential of hyponatremia

Electrolyte and Biomarker Studies
A value of Uosm < 100 mOsm/kg is indicative of a complete and appropriate suppression of antidiuretic hormone (ADH) secretion, a finding seen with either primary polydipsia (including ‘beer potomania’) or reset osmostat. Criteria used to diagnose the ‘beer potomania’ syndrome include
 * 1) A history of binge beer drinking
 * 2) Poor dietary intake
 * 3) Decreased serum sodium levels
 * 4) Low serum and urine osmolality
 * 5) Absence of other known causes of hyponatremia