A 52-year-old male with a history of chronic alcohol abuse was brought to the Emergency Department with a reported change in his mental state for 3 - 4 days. He was drowsy and lethargic but communicated appropriately when roused. He did not appear dehydrated . The following are his blood results on presentation:

Parameter

Patient Value

Normal Adult Range

Sodium

116 mmol/L*

135 - 145

Potassium

2.9 mmol/L*

3.5 - 5.0

Chloride

67 mmol/L*

95 - 110

Bicarbonate

14 mmol/L*

22 - 32

Urea

2.9 mmol/L*

3.0 - 8.0

Creatinine

46 umol/L

45 - 90

Glucose

6.8 mmol/L

3.5 - 7.8

Phosphate

0.60 mmol/L*

0.65 - 1.45

Maqnesium

0.51 mmol/L*

0.70 - 1.05

Calcium adjusted

2.31 mmol/L

2.10 - 2.60

Albumin

34 q/L*

36 - 52

Bilirubin total

13 umol/L

< 18

Alanine aminotransferase

67 U/L*

< 35

Asoartate transaminase

80 U/L*

< 40

Alkaline phosphatase

148 U/L*

30 - 110

y-Glutamyl transferase

480 U/L*

< 40

Lipase

492 U/L*

< 95

Amylase

189 U/L*

< 130

Free T4

14.2 omol/L

12.0 - 31.0

Thyroid stimulatinq hormone

0.65 mU/L

0.50 - 5.00

Cortisol

1440 nmol/L*

150 - 700

B-Hvdroxvbutyrate

4.4 mmol/L*

< 0.4

Osmolality

254 mOsm/L*

275 - 295

Urine Chemistrv

Sodium

< 20 mmol/L

Potassium

37 mmol/L

Osmolality

198 mOsm/L

a) Give the likely diagnosis with the rationale for your decision. (25% marks)

b) Briefly outline your management of the hyponatraemia in this patient. (20% marks)

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College answer

a) Beer potomania (alcoholic intoxication / ketoacidosis acceptable) 
History 
Abnormal LFTs with predominantly raised GGT 
Acidosis with elevated BOHB with normal glucose Low urine osmolality 
Normal endocrine profile 

 b) Likely chronic hyponatraemia so replace slowly < 10 mmol/24 hrs Stop non-essential fluids 
    At risk of seizures from alcohol withdrawal                
 

Discussion

Let us analyse the results in some detail.

This guy is a drinker, and his GGT is elevated, so... he has been drinking. 

After a few days of decreased level of consciousness he is not dehydrated, so ... he has been drinking a lot.

The bloods demonstrate hypoosmolar hyponatremia with a low usine osmolality and a low urine sodium. There are only a few conditions which can give rise to this:

  • Beer potomania
  • Psychogenic polydipsia
  • Excess 5% dextrose administration (psychogenic polydipsia by proxy, you might say)

Beer potomania is a case of dietary solute deficiency. Your water intake is excessive, but you eat virtually nothing containing salt. Lets say you are a degenerate beer-fiend, and your total nutritional intake consists of carbohydrate-rich, sodium-poor beer. Vast volumes are happily ingested. The carbohydrate from the beer is metabolised preferentially, leading to a suppression of protein catabolism. Low protein catabolism results in low urea levels, and with the sodium dropping, what solute can you excrete? None. The volume of urine drops. Each day you will excrete as little as 4 litres of maximally dilute urine. Obviously if you drink more than 4 litres of beer a day, hyponatremia will ensue. This phenomenon is not limited to American college students; ovolactovegetarians and people trying to lose weight too fast are also susceptible.

References

References

Hariprasad MK, Eisinger RP, Nadler IM, Padmanabhan CS, Nidus BD. Hyponatremia in psychogenic polydipsia. Arch Intern Med. 1980 Dec;140(12):1639-42.

Hilden T, Svendsen TL. Electrolyte disturbances in beer drinkers. A specific "hypo-osmolality syndrome". Lancet. 1975 Aug 9;2(7928):245-6.

Thaler SM, Teitelbaum I, Berl T. "Beer potomania" in non-beer drinkers: effect of low dietary solute intake. Am J Kidney Dis. 1998 Jun;31(6):1028-31.

Fox BD.Crash diet potomania. Lancet. 2002 Mar 16;359(9310):942.