An electrolyte panel is one of the most common blood tests you will meet in clinical work. This guide walks through how to read one in a systematic order, what the standard reference ranges are for sodium, potassium, and magnesium, and where to stop and hand interpretation to a clinician. Every number below is linked to its source, and where a source does not give a value, we say so rather than guess. Reference ranges vary by lab, so always read a result against the range printed on the report in front of you.
This article is educational and does not replace clinical training or advice for a specific patient. All clinical decisions rest with the treating clinician.
What is an electrolyte panel
An electrolyte panel is a blood test that reports the concentrations of key electrolytes. Alongside sodium, potassium, and magnesium, chloride and bicarbonate are also part of the electrolyte panel (StatPearls).
Sodium, potassium, and magnesium each have a widely used standard reference range. Chloride and bicarbonate are reported on the panel too, but the cited source does not give fixed numeric ranges for them, so this guide keeps chloride and bicarbonate qualitative and does not state specific numbers for them (StatPearls).
Because reference ranges vary by lab, treat the numbers below as the standard categories from the sources, not as universal cutoffs. The range printed on the actual report always takes priority.
How to read the panel step by step
Reading a panel in a fixed order helps you avoid missing a value. The point of this method is to notice which results fall outside the printed reference range, not to make a diagnosis. Diagnosis is made by a clinician.
Start with sodium
Read sodium first. The standard reference range for sodium is 135 to 145 mmol/L. As the standard categories per the source, a value under 135 is called hyponatremia and a value over 145 is called hypernatremia (StatPearls). Note whether the reported value sits inside, below, or above that range, and leave the clinical meaning to the treating clinician.
Move to potassium
Next read potassium. The standard reference range for potassium is 3.5 to 5.0 mmol/L (StatPearls). If the reported value falls outside 3.5 to 5.0 mmol/L, flag it as outside the standard reference range and pass it to a clinician for interpretation.
Check magnesium
Then read magnesium. The standard reference range for magnesium is 1.46 to 2.68 mg/dL (StatPearls). Confirm that the report is using mg/dL before comparing, because a value in a different unit will not line up with this range.
Read chloride and bicarbonate qualitatively
Finally, note chloride and bicarbonate. They are part of the panel, but the cited source does not give fixed numeric ranges for them here, so do not read them against a specific number from this guide (StatPearls). Compare each against the reference range printed on the report itself, and mark whether it is flagged low, normal, or high.
Standard reference ranges
The table below lists the standard reference ranges from the sources. Reference ranges vary by lab, so always check the range on the report.
| Electrolyte | Standard reference range | Source |
|---|---|---|
| Sodium (Na) | 135 to 145 mmol/L | StatPearls |
| Potassium (K) | 3.5 to 5.0 mmol/L | StatPearls |
| Magnesium (Mg) | 1.46 to 2.68 mg/dL | StatPearls |
| Chloride (Cl) | No fixed numeric range given in this source | StatPearls |
| Bicarbonate (HCO3) | No fixed numeric range given in this source | StatPearls |
Common mistakes
- Treating a single out-of-range value as a diagnosis. An out-of-range flag is a signal to interpret, and diagnosis is made by a clinician.
- Forgetting that reference ranges vary by lab. Always read a result against the range on the report, not a memorized number.
- Comparing magnesium in the wrong unit. The standard magnesium range here is in mg/dL, so check the unit before comparing (StatPearls).
- Assuming chloride and bicarbonate have the same fixed cutoffs as sodium. The cited source does not give fixed numeric ranges for chloride or bicarbonate, so do not invent one (StatPearls).
When to see a clinician
An electrolyte panel is a starting point, not a conclusion. Any value flagged outside the printed reference range should be interpreted by a clinician, together with the person’s history, symptoms, and other tests. If you are the patient and you have a result outside the standard range, or you have symptoms you are worried about, bring the report to a licensed clinician rather than acting on the numbers alone. This guide gives no treatment, dosing, or management advice, and all clinical decisions rest with the treating clinician.
How Phở Labs approaches this
Phở Labs writes with a cite-or-abstain rule. Every number in this guide is linked to its own source, and where a source does not give a value, such as fixed numeric ranges for chloride and bicarbonate, we state that plainly instead of guessing. That is the same honesty standard we hold ourselves to across the hub: name the source, or say the source does not say.