Sodium

Sodium is the main electrolyte in the fluid outside your cells, and it's central to fluid balance, blood pressure, and nerve and muscle function. Your body regulates it tightly, so an abnormal blood sodium usually reflects a problem with water balance rather than how much salt you eat. It's a standard part of the basic and comprehensive metabolic panels.

The typical reference range is 135 to 145 mmol/L (reported as mEq/L on many US panels, which is the same number). High sodium usually reflects dehydration or too little water for the amount of salt, while low sodium can come from drinking excess water, certain medications, or conditions like SIADH and adrenal insufficiency. Read your value against the range on your report.

Yes. Sodium concentration is really a reflection of the ratio of salt to water in your blood, so being dehydrated at the draw can raise it slightly and drinking a large volume of water beforehand can lower it. Hydrating normally rather than excessively before a fasted morning draw gives the most representative result. A value a point outside the range is rarely meaningful on its own.

Not in any meaningful way. Testosterone therapy doesn't change blood sodium, and normal training or creatine supplementation doesn't move it outside the reference range for people with healthy kidneys. Sodium is worth interpreting alongside your hydration and the rest of the electrolyte panel, and any persistent abnormality should be reviewed by your physician.