Empeiria

Low blood sodium

Clinically: Hyponatraemia · also low sodium, low salt in blood

electrolyte ICD-10 E87.1
This describes what this condition typically looks like. It is not a diagnosis and cannot tell you whether you have it -- patterns overlap, results vary between labs, and the same numbers mean different things in different people. Diagnosis usually rests on Sodium, interpreted alongside symptoms and history rather than read off a report.

unverified These explanations are written to be easy to read and have not yet been checked against a source. The ranges and measurement notes on this page show theirs.

definition unverified

The sodium in your blood is diluted. Usually this is about having too much water relative to salt, rather than too little salt in your diet.

Serum sodium concentration below 135 mmol/L, reflecting an imbalance of water to sodium in which water is in relative excess; total body water may be increased with normal sodium (euvolaemic), increased more than sodium (hypervolaemic), or sodium lost in excess of water (hypovolaemic). The fall in extracellular sodium drives water into cells, and brain-cell swelling causes many of the symptoms.

caveats unverified

How fast it fell matters more than the number. A slow drift can cause almost nothing; the same level reached quickly can be serious. Eating more salt is usually not the answer.

How fast it fell matters more than the number. A slow drift can cause almost nothing; the same level reached quickly can be serious. Eating more salt is usually not the answer.

No clinical version written yet.

The typical lab pattern

What the diagnosis rests on

The results a diagnosis is actually made on.

Sodium low — Hyponatraemia is defined by a serum sodium below 135 mmol/L. Some sources use below 136.
Consistent with it

Fits the picture, but not enough on its own.

Potassium either — Potassium helps find the cause: low potassium points to diuretics or vomiting, high potassium to adrenal insufficiency.

How it usually feels

Frequencies say how often a symptom accompanies this condition — not the other way round. Most people with any of these symptoms do not have this.