hypermagnesemia

Hypermagnesemia is a higher-than-normal level of magnesium in the blood. It is typically defined as a serum magnesium concentration above the upper limit of normal, commonly greater than 2.5 mg/dL (1.0 mmol/L). Clinically meaningful categories are mild (2.5–4.0 mg/dL), moderate (4.0–6.0 mg/dL), and severe (>6.0 mg/dL).

Most cases result from impaired renal excretion combined with excess magnesium intake or administration. The kidneys usually regulate magnesium balance, so underlying renal failure or reduced kidney function is the major risk factor. Other contributing factors include excessive use of magnesium-containing medications or products (such as certain laxatives or antacids), and, in some settings, medical use of intravenous magnesium sulfate (for example in obstetrics or preeclampsia) or large shifts of magnesium into the extracellular space.

Symptoms range from mild to life-threatening and may include nausea, flushing, and lethargy, followed by decreased deep tendon reflexes, hypotension, bradycardia, respiratory depression, and in severe cases coma or cardiac arrest. Neuromuscular and cardiovascular effects correlate with increasingly high magnesium levels and can be worsened by concurrent illness or electrolyte disturbances.

Diagnosis relies on serum magnesium measurement, interpreted in the clinical context. Urine magnesium and renal function tests may help identify the cause. Treatment focuses on stopping magnesium intake and removing the excess. For mild cases with preserved kidney function, this may involve monitoring and supportive care. Moderate to severe hypermagnesemia requires interventions such as intravenous calcium gluconate to counteract cardiac and neuromuscular effects, aggressive intravenous fluid administration, diuretics if kidney function is adequate, and definitive removal with dialysis in kidney failure or refractory cases. Prognosis improves with prompt recognition and appropriate management.