Which combination can cause hypermagnesemia?

• A. Renal failure with antacid ingestion
• B. Renal failure alone
• C. Liver failure with alcohol
• D. Dehydration with diuretics

Answer: (A)

Magnesium balance hinges on kidney excretion. When kidney function is impaired, the body can’t clear magnesium effectively, so levels rise. Adding a large magnesium load, such as magnesium-containing antacids, pushes serum magnesium up further. So the combination of renal failure plus ingestion of magnesium-containing antacids provides both a high intake and reduced clearance, making hypermagnesemia likely.

In other scenarios, the risk isn’t as strong: renal failure alone can raise magnesium but usually not dramatically without an additional magnesium source; liver failure with alcohol doesn’t inherently add a significant magnesium load; dehydration with diuretics tends to promote magnesium loss rather than retention.