Magnesium is abundant in the human body for good reason, acting as a cofactor in over 300 enzyme systems. These include protein synthesis, muscle and nerve function, blood sugar control (and here’s what happens to your blood sugar if you don’t get enough magnesium), and blood pressure regulation, to name a few.
As stated by the National Institutes of Health Office of Dietary Supplements (ODS), adults have around 25 grams of magnesium in their bodies, with about 50% to 60% stored in the bones and the remainder in soft tissues. Less than 1% is found in blood serum.
Serum magnesium is tightly regulated between 0.75 and 0.95 millimoles per liter (mmol/L). The kidneys play a crucial role in this regulation, excreting about 120 milligrams of magnesium daily through urine. However, in individuals with chronic kidney disease (CKD), magnesium levels could significantly increase.
How CKD affects serum magnesium levels
Authors of a 2023 narrative review in Nutrients detail that as the kidney’s glomerular filtration rate decreases, its ability to filter blood diminishes. This inefficiency leads to reduced magnesium excretion, resulting in excessive magnesium in the blood (hypermagnesemia).
A 2012 study in the Clinical Kidney Journal indicates that initially, kidneys can compensate and maintain normal magnesium levels in mild to moderate CKD. However, as CKD advances to stages 4 and 5, serum magnesium increases. End-stage renal disease often results in overt hypermagnesemia, especially in patients using magnesium-increasing medications like antacids and phosphate binders.
How high magnesium levels with CKD are treated
Low blood pressure unresponsive to medication may be an early sign of excessive magnesium. Symptoms of moderate to severe cases include dizziness, nausea, confusion, weakness, and difficulty breathing. Higher levels can lead to sleepiness, headache, constipation, muscle or bladder paralysis, abnormal heart rhythms, coma, or even cardiac arrest.
Experts emphasize the urgency of treating severe magnesium toxicity, including monitoring ECG, blood pressure, and neuromuscular function (via StatPearls). Treatment may involve intravenous calcium gluconate or chloride to counteract magnesium’s effects on the heart and muscles. Loop diuretics or hemodialysis may be required for increased magnesium excretion when kidney function is severely impaired. During treatment, it is crucial to monitor the patient’s electrolytes to prevent severe imbalances that could pose additional health risks.
