Study of Osteopontin as a Marker of Arteriovenous Shunt Stenosis in Hemodialysis Patients.

INTRODUCTION: Although arteriovenous fistula (AVF) is the recommended access for hemodialysis (HD), it carries a high risk for stenosis. Since osteopontin (OPN) is implicated in the process of vascular calcification in HD patients, OPN may be a marker for AVF stenosis. The present study evaluated OPN as a potential marker of AVF stenosis in HD patients. METHODS: Diagnosing a stenotic lesion was made by combining B mode with color and pulse wave Doppler imaging. Criteria for diagnosis of stenotic AVF included 50% reduction in diameter in B mode in combination with a 2-3-fold increase of peak systolic velocity compared with the unaffected segment. RESULTS: The present study included 60 HD patients with stenotic AVF and 60 patients with functional AVF. Comparison between the two groups revealed that patients in the former group had significantly higher serum OPN levels [median (IQR): 17.1 (12.1-30.4) vs 5.8 (5.0-10.0) ng/mL, p<0.001]. All patients were classified into those with low (< median) and with high (≥ median) OPN levels. Comparison between these groups revealed that the former group had a significantly lower frequency of stenotic AVF (31.7 vs 68.3%, p<0.001) and a longer time to AVF stenosis [mean (95% CI): 68.4 (54.7-82.1) vs 46.5 (39.6-53.4) months, p=0.001]. CONCLUSION: OPN levels in HD patients may be useful markers for predicting and detecting AVF stenosis.

Relation between myostatin levels and malnutrition and muscle wasting in hemodialysis patients.

BACKGROUND AND AIM: Malnutrition is one of the most troublesome comorbidities among hemodialysis patients (HD). Myostatin (MSTN) belongs to the transforming growth factor-ß superfamily. In HD patients, MSTN effects are not limited to skeletal muscle growth. The present study aimed to assess MSTN levels in HD patients and its relation to various clinical and biochemical parameters. PATIENTS AND METHODS: The present case control study included 60 patients on HD for at least three years. In addition, there were age and sex-matched healthy subjects who constitutes the control group. Nutritional status was evaluated using the malnutrition inflammation score (MIS). Muscle wasting in the present study was evaluated using the lean tissue index (LTI) as assessed by the body composition monitor (BCM). Rectus Femoris Muscle (RFM) thickness was also measured as indicator for nutritional status of patient. RESULTS: The present study included 60 HD patients, and ageand sex-matched healthy controls. Patients expressed significantly higher myostatin levels when compared to controls [median (IQR): 221.3 (153.5-688.2) versus 144.8 (97.0-281.7), p < 0.001]. According to MIS, patients were classified into those with no/mild malnutrition (n = 22) and others with moderate/severe malnutrition (n = 38). Comparison between the two subgroups revealed that the former group had significantly lower myostatin levels [167.7 (150.3-236.3) versus 341.7 (160.9-955.9), p = 0.004]. According to LTI, patients were classified into those with muscle wasting (n = 23) and others without muscle wasting (n = 37). Comparative analysis showed that patients in the former group had significantly higher myostatin levels [775.1 (325.1-2133.7) versus 161.8 (142.6-302.3), p < 0.001]. CONCLUSIONS: Myostatin seems to be a promising marker for identification of malnutrition and muscle wasting in HD patients.