Magnesium

Blood magnesium levels provide an early indicator of deficiency or excess before severe symptoms develop. Low levels can increase risk for cramps, twitches, fatigue, restless sleep and constipation, while high levels, often from supplements or kidney problems, can affect blood pressure and heart rhythm. Ensuring adequate intake through leafy greens, nuts, seeds, whole grains and proper hydration helps maintain healthy magnesium levels and reduce long-term health risks.

Most adults benefit from checking serum magnesium once a year. If you take diuretics, long-term proton pump inhibitors, or have a condition affecting absorption, retest every six months. After starting supplementation, retest at 8 to 12 weeks.

At baseline / for screening: Once every 12 months from age 30 as part of a comprehensive panel. More frequently, every 6 months, if you take diuretics, long-term proton pump inhibitors, or have a condition affecting absorption.

When monitoring an intervention or change: Retest 8 to 12 weeks after starting magnesium supplementation or making a sustained change in dietary intake (leafy greens, nuts, seeds, legumes). After starting medication that depletes magnesium (diuretics, long-term PPIs), retest at 3 months to track stable function.

Note: Serum magnesium reflects only about 1 percent of total body magnesium and can be normal despite functional deficiency. Wait 8 to 12 weeks after starting supplementation before reading the next value as a stable baseline.