[Characteristics of hyperhomocysteinemia in dialysis patients]

The aim of the study was to determine the prevalence of hyperhomocysteinemia and its relationship with other cardiovascular risk factors in dialysis patients.

Blood pressure and biochemical indicators (creatinine, urea, total cholesterol, LDL cholesterol, HDL cholesterol and triglycerides) were determined by standard methods in 46 dialysis patients. Homocysteine (Hcy) was determined by the method of stable isotopic dilution mass spectrometry. ECHO of the heart was used for the parameters necessary for calculation of the left ventricular mass index. Left ventricular hypertrophy was defined as a left ventricular mass index higher than 109 +/- 20 g/m2 for males and higher than 89 +/- 15 g/m2 for females. Delivered dosage of dialysis (Kt/V) was calculated by Daugirdas formula.

Arterial hypertension was present in 72% and left ventricular hypertrophy in 82% of study subjects. An increased concentration of total homocysteine (tHcy) (mean 24.76 +/- 11.04 micromol/L) was observed in 85% of subjects. Dyslipemia was manifested by increased concentration of tChol in 22%, elevated values of LDL Chol in 26%, decreased concentration of HDL Chol in 50%, and hypertriglyceridemia in 46% of study subjects. There was no statistically significant correlation of plasma tHcy concentration with age (p > 0.5), creatinine (p > 0.2), time on dialysis (p > 0.9), dosage of dialysis (p > 0.78) and left ventricular mass index (p > 0.19).

Numerous studies have shown that mild to moderate elevation of plasma tHcy concentration (tHcy 15-30 micrtomol/L, and 30-100 micromol/L) occurs in 5%-7% of the general population and in 85%-90% of dialysis patients. In our study, hyperhomocysteinemia was present in 85% of patients. Increased tHcy concentration in plasma of uremic patients is one of non-traditional atherosclerosis risk factors, acting synergestically with traditional risk factors for cardiovascular diseases in uremic patients. In patients on hemodialysis, dyslipidemia is generally characterized by increased concentrations of LDL cholesterol and triglycerides, and a decreased concentration of HDL cholesterol, as also confirmed by our study. In 43.5% of patients, inadequate dosage of dialysis is the consequence of insufficient function of the A-V fistula and lack of patient cooperation. Left ventricular hypertrophy is an independent risk factor for cardiovascular disease, while hypertension is one of its main causes. Literature data indicate that elevated arterial pressure and Hcy affect the degree of cardiac hypertrophy independently, and that Hcy is in direct correlation with heart failure for which decreased diastolic function is not responsible. Some 57%-93% of hemodialysis patients have left ventricular hypertrophy. In our study, left ventricular hypertrophy was observed in 81% of patients, of which 86% had arterial hypertension.

The study has confirmed hyperhomocysteinemia in as many as 85% of patients. There was no positive correlation of Hcy concentration with patient age, time on dialysis, serum creatinine, adequacy of dialysis, left ventricular mass index. Cardiovascular diseases are common in dialyzed patients with hyperhomocysteinemia, suggesting a causal relationship since Hcy is an independent atherosclerosis risk factor. However, additional studies in a large number of subjects will hopefully provide more comprehensive answers.