31/10/2025
How magnesium balance goes wrong
Magnesium is a key electrolyte for nerve signaling, muscle contraction, and heart rhythm. Because it regulates over 300 enzymatic reactions, both low and high magnesium levels can disrupt nearly every system in the body. This diagram shows how magnesium metabolism becomes deranged through dietary deficits, renal loss, or metabolic disease.
1️⃣ When magnesium supply is low
Poor intake, malabsorption, or chronic diarrhea reduce magnesium absorption from the gut.
🟢 Example: Long-term proton pump inhibitor use or celiac disease can cause gradual depletion and low serum magnesium.
2️⃣ Renal magnesium loss
The kidneys fine-tune magnesium reabsorption, but several conditions—such as loop diuretics, alcoholism, hyperaldosteronism, or Bartter’s syndrome—increase urinary loss.
🟢 Example: Loop diuretics (like furosemide) block magnesium and calcium reabsorption in the nephron, leading to hypomagnesemia.
3️⃣ Cellular uptake and insulin
Insulin helps drive magnesium into cells, so insulin deficiency or resistance (as in diabetes mellitus) causes extracellular buildup and intracellular depletion.
🟢 Example: In type 2 diabetes, magnesium inside muscle cells falls while serum levels appear normal, contributing to fatigue and insulin resistance.
4️⃣ Hypomagnesemia (low magnesium)
Chronic loss lowers magnesium in blood and tissues, increasing neuronal excitability.
🟢 Symptoms: Tachycardia, arrhythmias, cramps, tremors, depression, and reduced parathyroid hormone (PTH) release, which in turn lowers calcium.
5️⃣ Hypermagnesemia (high magnesium)
Usually occurs from renal failure or excessive magnesium intake (e.g., antacids or laxatives) when the kidneys cannot excrete it efficiently.
🟢 Symptoms: Muscle weakness, low reflexes, constipation, vomiting, hypotension, and in severe cases, respiratory arrest or cardiac arrhythmia.
6️⃣ Bidirectional relationship with calcium and potassium
Magnesium deficiency disrupts calcium and potassium transport—lowering both and amplifying muscle irritability and arrhythmia risk.
🟢 Example: Restoring magnesium is often the first step before potassium can be normalized.
Magnesium’s balance depends on diet, kidneys, and hormonal control. Too little excites the nervous system; too much suppresses it. The result is a tight physiological window where even small shifts in magnesium can alter the rhythm, reflex, and stability of the entire body.