Urinary kidney injury molecule-1 levels as a marker of early kidney injury in hypertensive patients

BACKGROUND: Kidney injury molecule -1 (KIM -1) is a type 1 tubular cell transmembrane protein that is found in high levels in early stages of acute kidney injury and is stated to have predictive value in the early diagnosis of chronic kidney diseases. In this study, the hypothesis was that higher levels of KIM -1 would be detected in hypertensive patients for the early detection of nephropathy. With this goal, urinary KIM -1 levels of hypertensive cases were compared with those of healthy controls, and associations of KIM -1 levels with microalbuminuria and glomerular filtration rate (GFR) were investigated. METHODS: The study included a total of 80 patients aged >= 20 years (55 male, 25 female, mean age: 57.21 +/- 9.12 years). The patient group consisted of 40 patients (28 males, 12 females, mean age: 57.58 +/- 8.79 years) who had had hypertension for at least 5 years, and the control group consisted of 40 healthy subjects (27 female, 13 male, mean age: 56.85 +/- 9.53 years). Groups were compared based on demographic, anthropometric and biochemical data, and urinary KIM -1 levels. Correlation analysis was made to assess the association of KIM -1 levels with microalbuminuria and GFR. Levels of urinary KIM -1 enzyme were measured using linked immunosorbent assay (ELISA). RESULTS: KIM -1 levels were found to be 0.86 +/- 0.48 ng/mg creatinine in the patient, and 0.71 +/- 0.46 pg/mL in the control groups (P>0.05). A positive correlation was detected between KIM -1 levels and both systolic blood pressure and duration of disease (r=0.308, P=0.032 and r=0.339, P=0.032, respectively). CONCLUSIONS: While not supporting the hypothesis that KIM -1 levels may increase in hypertensive patients as an early indicator of hypertensive nephropathy, these findings suggested that this molecule might be associated with kidney injury in hypertensive nephropathy due to its positive correlation with the duration of hypertension.