Sodium

Sodium levels reveal how well your body maintains fluid balance and supports nerve and muscle function. Low sodium can cause fatigue, confusion, or muscle cramps, while high sodium may indicate dehydration or kidney issues. Maintaining adequate hydration, a balanced diet, and kidney health helps keep sodium levels within a healthy range and supports overall cellular and cardiovascular function.

Most adults benefit from checking sodium once a year as part of standard electrolyte screening. If you take diuretics, SSRIs, or have a condition affecting fluid balance, retest every three to six months.

At baseline / for screening: Once every 12 months from age 30 as part of a comprehensive metabolic panel. More frequently, every 3 to 6 months, if you take diuretics, ACE inhibitors, ARBs, or have a condition affecting fluid balance.

When monitoring an intervention or change: Retest 2 to 4 weeks after starting or adjusting medication that affects sodium balance (diuretics, SSRIs, some antiepileptics). Single readings respond to hydration on the morning of the draw, with overhydration lowering and dehydration raising values, so reproduce conditions for meaningful comparison. After acute illness with vomiting or diarrhoea, retest once you've recovered.

Note: After vigorous exercise with sweating, or significant fluid imbalance (diarrhoea, vomiting, very high or low water intake), wait 24 to 48 hours before retesting to allow electrolyte balance to restore.