Relationship between Fetuin-A and vascular or valvular calcification in hemodialysis patients

Abstract

Introductions. Vascular and valvularcalcification are the important risk factors for cardiovascular disease in patients with End Stage Kidney Disease (ESKD). It is assumed that deficiency of Fetuin A, as a calcification inhibitor, involves in vascular calcification. This study aimed to examine the relationship between serum Fetuin A and vascular and valvular calcification in a cohort of hemodialysis patients. Methods. This cross-sectional study was conducted on 122 patients on maintenance hemodialysis of Hasheminejad Kidney Center in Tehran 2013. Blood samples were tested for lab parameters including Calcium (Ca), Phosphorus (P), parathyroid hormone (PTH), highly sensitive C reactive protein (hCRP), 25 OH Vitamin D3 level and Fetuin A. Doppler sonography was performed for assessment of intima-media thickness (IMT) and stenosis in carotid arteries. A stenosis of more than 50%, the presence of each of the items of hypoechoic plaque or calcification, or a mean IMT >= 0.8mm, were considered as evidence for vascular calcification. Calcification of cardiac valves or mitral annular calcification (MAC), studied by two-dimensional echocardiography, was considered as an evidence for cardiac valvular calcification. The presence of each of the two conditions was considered as cardiovascular calcification. Laboratory findings were compared between the two groups of patients with and without cardiovascular calcification and its predictors were determined. Results. Of a total of 122 patients, 74 patients (61%) were male and the mean age was 58 +/- 16 years. The most common causes of ESKD were diabetes (46%) . The median dialysis vintage was four years. Mean Fetuin-A level was 36.5 +/- 6.9mg/dL. In 77 patients (63%) Fetuin-A was within the normal range (35-100 mg/dL) and in 45 patients (37%) it was lower than the normal range. Ninety-two patients (75%) had vascular calcification and 89 patients (73%) had valvular calcification. In 75 patients (62%) both types of calcification were observed. Totally 106 patients (87%) had cardiovascular calcification. The patients with cardiovascular calcification were older (38 +/- 14yr vs. 61 +/- 14yr, P < 0.001); more affected by diabetes melitus (13% vs. 54%, P = 0.007), and had a longer history of dialysis (median of 2 yr vs. 5 yr, P = 0.006). Concerning the laboratory test results, patients with calcification also had lower levels of creatinine (8.9 +/- 2.8 mg/ dL vs. 11.9 +/- 3.1md/dL, P < 0.001) and higher levels of calcium (8.7 +/- 0.7mg/dL vs. 8.4 +/- 0.5mg/ dL, P = 0.026). There was no quantitatively and qualitatively significant difference between the two groups in terms of Fetuin-A (P = 0.101 and P = 0.956, respectively). Logistic regression showed that each year of increase in age, each unit increase in calcium, and the presence of diabetes melitus increased the odds ratio of calcification by 1.1 times (OR = 1.1, CI 95% = 1.1-1.2), 2.8 times (OR = 2.8, CI 95% = 1.1 to 7.6), and 7 times (OR = 7.4, CI 95% = 1.1-47.4), respectively . Conclusions. The findings of this study showed that 87% of our hemodialysis patients had either vascular or valvular calcification. In addition, age, calcium level, and diabetes were identified as the most important predictors of calcification. There was no significant difference between the two groups with and without calcification in terms of Fetuin A.