People who've had a kidney transplant with lower magnesium in their blood tend to have higher levels of the anti-rejection drug tacrolimus and better kidney function, according to this observation.

We analyzed the available evidence and found that 36 observations suggest a link between lower blood magnesium levels and higher tacrolimus levels, along with better kidney function, in people who’ve had a kidney transplant [1]. These observations show a pattern: when magnesium in the blood is lower, tacrolimus — the drug used to prevent organ rejection — tends to stay at higher levels in the body, and kidney function appears to improve. We did not find any studies or observations that contradict this pattern. However, it’s important to note that these are observational reports, not controlled experiments. That means we can’t say low magnesium causes higher tacrolimus or better kidney function — only that the two tend to appear together in these cases. The exact reason for this connection isn’t clear from the data we’ve reviewed. It could be that low magnesium affects how the body processes tacrolimus, or that other factors, like diet or medication timing, are influencing both magnesium and drug levels. We also don’t know if lowering magnesium intentionally would help or harm transplant patients. Magnesium is essential for many body functions, including heart rhythm and muscle control, and too little can cause problems. The evidence we’ve reviewed doesn’t tell us whether adjusting magnesium levels is safe or useful in this context. What we’ve found so far points to a consistent association, but not a clear cause-and-effect relationship. More research is needed to understand why this pattern exists and whether it can be used to guide treatment. For now, if you’re a kidney transplant patient, don’t change your magnesium intake without talking to your care team. Your doctor can monitor your levels and adjust your medications safely based on your full health picture.