Magnesium, Serum

Magnesium is an important mineral that your body needs to keep muscles, nerves, and the heart working properly. This blood test measures the amount of magnesium circulating in your bloodstream. Low magnesium can cause muscle cramps, irregular heartbeat, and other symptoms, and is often related to diet, certain medications, or conditions affecting the gut or kidneys. High magnesium is less common and is usually seen in people with kidney problems or those taking too many magnesium-containing supplements or antacids. Your doctor will consider this result alongside your other test results and overall health to determine if any action is needed.

When elevated: Hypermagnesemia can cause progressive neuromuscular depression, including hyporeflexia, muscle weakness, respiratory paralysis, and cardiac conduction abnormalities such as bradycardia, heart block, and cardiac arrest at severely elevated levels. Mild elevations may be asymptomatic but warrant investigation for underlying cause. When low: Hypomagnesemia is associated with neuromuscular excitability (tremors, tetany, seizures), cardiac arrhythmias including torsades de pointes, refractory hypokalemia and hypocalcemia, and impaired insulin secretion. Chronic low magnesium has been epidemiologically associated with increased cardiovascular risk, type 2 diabetes, and hypertension, though causality is not fully established.

Magnesium supports muscle contraction, energy production (ATP), and nervous system function—all critical during training and recovery. Athletes with high sweat losses, restrictive diets, or intense training may experience marginal depletion, potentially affecting muscle function and recovery efficiency, though clinical deficiency is uncommon in well-nourished individuals.