Cardiac troponin T (cTnT) in hemodialysis patients with asymptomatic and symptomatic atherosclerosis

BACKGROUND: Cardiovascular mortality is higher in hemodialysis (HD) patients than in the general population. Cardiac troponin T (cTnT) is established as a sensitive marker of myocardial injury in the general population. Less is known about the association between cTnT and intima-media thickness (IMT) and presence of plaques in carotid arteries (asymptomatic atherosclerosis) and prognostic value of cTnT for cardiovascular mortality (symptomatic atherosclerosis) in HD patients. METHODS: In our study 90 HD patients (mean age 56.2 +/- 13.3 years) were followed after determination of cTnT level. Outcome after 21 months was chosen as the end point. In 52 randomly selected HD patients, IMT was measured with B-mode ultrasonography. Plaque occurrence and their numbers were also determined. RESULTS: In 24 (26.6%) patients, cTnT values were >0.1 microg/L (positive test for myocardial injury). During follow-up, 13 patients died from cardiovascular causes and their cTnT values were significantly higher (0.12 vs. 0.06 microg/L; p <0.001) than in those who survived. Correlation between cardiovascular mortality and cTnT was found (p <0.001). The cut-off level of 0.1 microg/L resulted in survival rates of 92% and 64% (p=0.0006). The IMT values of carotid artery were significantly higher (0.85 vs. 0.70 mm; p <0.011) in patients with elevated cTnT. All patients with elevated cTnT had plaques and the number of plaques was significantly higher in these patients (p <0.0001). CONCLUSIONS: cTnT was frequently elevated in our HD patients and was associated with higher cardiovascular mortality and a predictor of cardiovascular outcome. Patients with elevated cTnT showed advanced asymptomatic atherosclerosis in carotid arteries.     

Role of ultrasound in the preoperative staging of patients with breast cancer

The aim of this study was to evaluate the ability of axillary ultrasound (US) and US-guided fine-needle aspiration biopsy (FNAB) to detect axillary LN metastases. Between January 2001 and September 2003, axillary US was performed in 165 patients with cytologically or histologically proven breast cancer and clinically non-palpable axillary LNs. In patients with US suspicious LNs, US-guided FNAB was performed and patients with cytologically proven malignant LNs proceeded directly to the ALND. In 49/90 patients with US suspicious LNs, US-guided FNAB was performed. It was positive in 33/49 patients. Definitive histology report revealed LN metastases in 65/165 patients. The sensitivity, specificity, positive and negative predictive value of the US-FNAB, were 84, 91, 97 and 62%. Axillary US in a combination with US-FNAB is a valuable method in preoperative staging of patients with breast cancer. Almost 50% of patients with LN metastases can be spared the second operation. However, it is very much operator-dependent and equipment-dependent.     

Vitamin D as a Novel Nontraditional Risk Factor for Mortality in Hemodialysis Patients

We examined the prevalence of vitamin D deficiency in hemodialysis patients and tested the hypothesis that decreased levels of 25‐hydroxyvitamin D (25D) are associated with an increased risk for early all‐cause mortality. One hundred and two patients, 57 (56%) men and 45 (44%) women, mean age 60.5 ± 13.1 years, were included in our study. Serum calcium and phosphorus levels were measured by routine laboratory methods. Parathyroid hormone (PTH) was measured by immunoassay and 25D by enzyme immunoassay. Patients were divided into two groups depending on the serum concentration of 25D: below or above 50 nmol/L. Survival rates were analyzed using the Kaplan–Meier survival curves. The Cox regression model was used to define potential variables effecting all‐cause mortality. The mean level of 25D in all patients was 58 ± 35.6 nmol/L, 52% of patients had 25D levels >50 nmol/L and 48% had levels of 10.5–50 nmol/L. Compared with men, women were more likely to be 25D deficient (67% vs. 37%; P = 0.005). Patients were observed from the date of laboratory measurement until their death or to a maximum of 730 days. Kaplan–Meier survival analysis showed that mortality in patients was significantly higher in the group with 25D levels ≤50 nmol/L (P < 0.033). With Cox multivariable regression modeling, the PTH level (P < 0.029) turned out to be the only predictor of mortality in our patients. Using the definitions recommended in the National Kidney Foundation Kidney Disease Outcomes Quality Initiative guidelines, we found that our hemodialysis patients on average have vitamin D insufficiency. Our results indicate that patients with 25D levels ≤50 nmol/L are associated with higher all‐cause early mortality.     

Serum cystatin C as an endogenous marker of renal function in the elderly

The glomerular filtration rate (GFR) is the main indicator of kidney function. In clinical practice the GFR is often estimated from serum creatinine. In the elderly, serum creatinine is notoriously unreliable as an estimator of GFR. Recently, serum cystatin C has been proposed as a new endogenous marker of glomerular filtration rate. A total of 144 patients, aged more than 60 years (mean age 70.4 years), who had undergone 51CrEDTA clearance, were enrolled in our study. In each patient serum creatinine and serum cystatin C were determined. The reciprocal of serum creatinine, the reciprocal of serum cystatin C and creatinine clearance (from Cockcroft and Gault formula) were calculated. Serum cystatin C was measured with the particle-enhanced immunonephelometric method. The mean 51CrEDTA clearance was 34.5+/-25.55 ml/min/1.73 m2, the mean serum creatinine was 312+/-210 micromol/l and the mean serum cystatin C 3.15 mg/l+/-1.62 mg/l. We found a significant correlation between 51CrEDTA clearance and serum creatinine, serum cystatin C, the reciprocal of serum creatinine and the reciprocal of serum cystatin C as well as with creatinine clearance. In comparison of the correlation coefficients we found that the correlation between 51CrEDTA clearance and serum cystatin C was significantly better than that with serum creatinine (p < 0.05). The correlation between 51CrEDTA clearance and the reciprocal of serum cystatin C was superior to that with the reciprocal of serum creatinine (p < 0.003) and calculated creatinine clearance (p < 0.003). Our results indicate that serum cystatin C is a more reliable marker of GFR in the elderly than serum creatinine or creatinine clearance.     

Hemodialysis vascular access thrombosis and lipoprotein(a)

Background. Vascular access remains the Achilles's heel of successful hemodialysis and thrombosis is the leading cause of vascular access failure. Elevated lipoprotein(a) (Lp(a)) levels in hemodialysis patients were reported, and in some studies were also associated with hemodialysis vascular access thrombosis. Patients and methods. In our study 84 hemodialysis patients with native arteriovenous fistula were included. Two groups of patients were defined: group A including 61 patients with their vascular access either never or only once thrombosed, and group B including 23 patients with two or more thromboses of their vascular access. We determined serum concentrations of Lp(a) in all our patients. Results. Average serum Lp(a) concentration for all the patients included in the study was 0.273 +/- 0.31 g/l. No relationship was found between serum Lp(a) concentrations and age, gender and duration of dialysis treatment. Serum Lp(a) concentrations were higher in group A than in group B patients (0.301 g/l versus 0.198 g/l), but the difference was not statistically significant. There was also no statistically significant difference between group A and group B regarding age, gender and duration of hemodialysis treatment. The use of a cut-off value for Lp(a) of 0.3 g/l and 0.57 g/l also failed to provide a significant difference between group A and B patients. Conclusion. We found no significant differences in Lp(a) concentrations between group A (thrombosis-non-prone) and group B (thrombosis-prone) patients. Our results suggest that Lp(a) is not an independent risk factor for vascular access occlusion in hemodialysis patients.     

Serum Cystatin‐C as a Marker of Acute Kidney Injury in the Newborn After Perinatal Hypoxia/Asphyxia

We evaluated cystatin‐C (cysC) in the umbilical blood as a predictor of acute kidney injury (AKI) after perinatal hypoxia/asphyxia compared with creatinine (Cr). One hundred full‐term newborns were enrolled in the study (50 in a group affected by perinatal hypoxia/asphyxia [AS] and 50 controls). CysC and Cr were measured in blood samples from the umbilical cord at birth (cysC‐umb and Cr‐umb) and from a peripheral vein 3 days later (cysC‐3 and Cr‐3). At birth, the mean level of cysC in healthy term babies was found to be 1.39 ± 0.19 mg/L and 1.34 ± 0.21 mg/L after 3 days of life, not significantly decreased (P = 0.137). The mean of cysC in the AS group was 2.12 ± 0.53 mg/L in cord blood and 1.56 ± 0.32 g/L in day 3 blood samples, also decreased (P < 0.001) and different from the control (P < 0.001). Cr levels, determined simultaneously at birth were different (P = 0.001) between the control (62.74 ± 12.84 μmol/L) and AS (72.60 ± 15.55 μmol/L) group, significantly decreased after 3 days in both groups (P < 0.001). The receiver‐operating characteristic curve analysis, comparing AS and the control group, showed area under the curve for cysC‐umb, cysC‐3, Cr‐umb and Cr‐3 (0.918; 0.698; 0.692; 0.660). The highest diagnostic accuracy was achieved with a chosen cut‐off for cysC‐umb of 1.67 mg/L (sensitivity of 84.0%, specificity of 90.0%) or 1.69 mg/L (sensitivity of 82.0%, specificity of 94.0%). Our results indicate serum CysC is a more sensitive marker of glomerular filtration rate than Cr in the newborns.     

Serum cystatin C as an endogenous marker of renal function in patients with mild to moderate impairment of kidney function.

BACKGROUND: Estimation of the glomerular filtration rate (GFR) is essential for the evaluation of patients with chronic kidney disease (CKD). Recently, serum cystatin C was proposed as a new endogenous marker of GFR and in our study its diagnostic accuracy was compared with that of other markers of GFR. METHODS: In this study, 164 patients with CKD stages 2-3 (GFR 30-89 ml/min/1.73 m2), who had performed 51Cr-labelled ethylenediaminetetra-acetic acid clearance, were enrolled. In each patient, serum creatinine and serum cystatin C were determined. Creatinine clearance was calculated using the Cockcroft-Gault (C&G) and the modification of diet in renal disease (MDRD) formulas. RESULTS: The mean 51CrEDTA clearance was 57 ml/min/1.73 m2, the mean serum creatinine 149 micromol/l and the mean serum cystatin C 1.74 mg/l. We found significant correlation between 51CrEDTA clearance and serum creatinine (R = -0.666), serum cystatin C (R = -0.792), reciprocal of serum creatinine (R = 0.628), reciprocal of serum cystatin C (R = 0.753) and calculated creatinine clearance from the formulas C&G (R = 0.515) and MDRD formulas (R = 0.716). The receiver operating characteristic (ROC) curve analysis (cut-off for GFR 60 ml/min/1.73 m2) showed that serum cystatin C had a significantly higher diagnostic accuracy than serum creatinine (P = 0.04) and calculated creatinine clearance from the C&G formula (P < 0.0001), though only in female patients. No difference in diagnostic accuracy was found between serum cystatin C and creatinine clearance calculated from the MDRD formula. CONCLUSIONS: Our results indicate that serum cystatin C is a reliable marker of GFR in patients with mildly to moderately impaired kidney function and has a higher diagnostic accuracy than serum creatinine and calculated creatinine clearance from the C&G formula in female patients.