# L-arginine Results in an Artificial Increase in Creatinine

## TL;DR

This paper shows that L-arginine, a common supplement, can falsely raise creatinine levels, a marker for kidney function.

## Contribution

The study demonstrates that L-arginine can artificially elevate serum creatinine, independent of kidney function.

## Key findings

- A 65-year-old man's creatinine levels normalized after stopping L-arginine.
- Cystatin C levels remained stable, indicating no real kidney damage.
- L-arginine use was directly linked to the artificial creatinine increase.

## Abstract

L-arginine is a commonly available over-the-counter supplement. We report a 65-year-old man with a history of benign prostatic hyperplasia, hypertension, and obstructive sleep apnea who had an elevated serum creatinine level and normal cystatin C in the setting of L-arginine supplementation. After discontinuation of L-arginine, repeat testing showed normalization of serum creatinine, while cystatin C remained unchanged, thus demonstrating that L-arginine use can result in an artificial increase in serum creatinine.