Magnesium RBC Test in California

The Magnesium RBC Test measures the amount of magnesium inside red blood cells. It is often ordered when a standard serum magnesium test is normal but a person still has symptoms or conditions linked to low magnesium, such as muscle cramps, weakness, or irregular heartbeat.

What it measures

Magnesium (RBC) — The concentration of magnesium inside red blood cells, which reflects body stores better than a serum test.
Hemoglobin — A protein in red blood cells that carries oxygen; measured to help interpret the magnesium result.
Hematocrit — The percentage of blood made up of red blood cells; used to check for anemia or other blood conditions.

Who it is for

This test is typically ordered by a doctor for people with symptoms of magnesium deficiency, such as muscle twitching, fatigue, or abnormal heart rhythms, or for those with conditions that affect magnesium levels, like kidney disease or diabetes.

Preparation

No fasting is required for this test. You can eat and drink normally before your blood draw, but tell your doctor about any medications or supplements you take, as some can affect magnesium levels.

Results and what they mean

Results are reported as a number for magnesium in red blood cells, along with a reference range. Your doctor will interpret the result in the context of your symptoms, other tests, and medical history. This information is not medical advice; always discuss your results with a qualified healthcare professional.

Requesting the Magnesium RBC Test in California

Order online, choose a certified collection site in California, and review results through a secure portal. No referral is required, and orders are processed confidentially. With coastal metros, inland towns, and rural counties with very different access to testing, it pays to schedule your collection in advance.

Frequently asked questions

How is this test different from a regular magnesium blood test?

A regular serum magnesium test measures magnesium in the liquid part of blood, which can be normal even when body stores are low. The RBC test measures magnesium inside red blood cells, giving a better picture of long-term magnesium status.

Do I need to fast for this test?

No, fasting is not required. You can eat and drink as usual before the blood draw.

What can affect my results?

Certain medications, supplements, and health conditions can affect magnesium levels. Always inform your doctor about what you are taking.

How soon will I get my results?

Results are typically available within 1 to 3 business days. Your doctor will discuss what the results mean for you.

Magnesium RBC Test by city in California

All testing in California → Full Magnesium RBC Test guide →