A clinically oriented review of cystatin c in hospitalized adults: when creatinine misleads-A practical guide for internists and its role in heart failure risk stratification.

Accurate assessment of kidney function is essential in hospitalized patients. However, serum creatinine does not always reflect true kidney function because it can be influenced by factors such as muscle mass, diet, and medications. When creatinine-based estimates are unreliable, cystatin C may serve as a useful complementary marker for internists. Compared with creatinine, cystatin C is less affected by these factors and may respond more rapidly to changes in glomerular filtration, which can improve recognition of kidney dysfunction and help refine chronic kidney disease (CKD) staging in hospitalized patients. In addition, cystatin C has prognostic value in heart failure, where elevated levels have been associated with higher risks of mortality and hospitalization. Together, these findings support the selective use of cystatin C for risk stratification and clinical decision-making in appropriate inpatient settings.