Evaluation of renal function in a patient with terminal rectal cancer who developed morphine hydrochloride-induced respiratory depression.

A challenge in patients with terminal cancer is that serum creatinine-based estimates of renal function often deviate from true renal function because cachexia-related loss of muscle mass leads to abnormally low serum creatinine levels. Serum cystatin C is a useful marker of renal function in patients with decreased muscle mass; however, there are limited data on its use in patients with terminal cancer. In this study, we present a detailed assessment of renal function, incorporating muscle mass measurement by bioelectrical impedance analysis, in a patient with terminal rectal cancer who developed respiratory depression while receiving a stable dose of morphine hydrochloride injections.