Low fluid intake—especially with sweating, fever, vomiting, or diarrhea—can cause dehydration and raise measured creatinine. This can be transient and normalize with rehydration and rest. Persistently low hydration may worsen kidney perfusion in vulnerable individuals. However, excessive water is not always safe either, particularly in high-risk groups. The most reliable approach is personalized hydration planning, risk-factor control, and periodic kidney function monitoring.