INTRODUCTION AND AIMS: On-line hemodiafiltration (HDF) can efficiently remove uremic toxins, ranging from small- to large-molecular-weight toxins, by both diffusion and convection. β2-Microglobulin (MG) (MW, 11.8 kDa; Stoke’s radius, 15.6A) is an important marker of dialysis efficiency. However, β2-MG is a little small as a marker for evaluation of the removal efficiency of HDF. Therefore, α1-MG (MW, 33 kDa; stokes radius, 28.4A) is preferable as a marker in HDF. The removal of α1-MG and albumin (Alb) (MW, 66 kDa; stokes radius, 35.5A) separately is difficult even by HDF. Therefore, Alb leakage during HDF is unavoidable when removing middle- and large-molecular-weight substances. In this study, we investigated the relationship between the removal efficiency of low-molecular-weight protein (LMWP) and the amount of Alb leakage in HDF. We also present here typical cases in which clinical symptoms significantly improved after efficient removal of α1-MG.
METHODS: The study subjects were 40 patients who had undergone HDF (241 times in total) in 2017 (Qb, 265.6±29.5 mL/min; Vs, 49.3±10.8 L/session). The removal efficiencies of β2-MG and α1-MG and the amount of Alb leakage were evaluated. The relationship between the removal rate of each solute and the amount of Alb leakage was examined. The change in serum Alb levels in 30 patients who underwent high-efficiency HDF (removal rates of β2-MG and α1-MG, 83% and 37%, respectively; amount of Alb leakage, 4.2±1.6g/session) for 1 year was examined.
RESULTS: Analysis of the test results showed that the removal rates of β2-MG and α1-MG were 82.0 ± 4.5% and 34.7 ± 9.3%, respectively. The Alb leakage was 3.9 ± 1.7g/session. Figure shows the correlations between the amount of Alb leakage and the β2-MG and α1-MG removal rates. The approximate curve of the amount of Alb leakage was closely correlated to that of α1-MG removal rate Although the MW of Alb is two times higher than that of α1-MG, the difference in Stoke’s radius between them is 20%. Thus, the present study confirmed that the removal of α1-MG and Alb separately was impossible with the current dialyzer membrane. The serum Alb level of 30 patients who underwent high-efficiency HDF was 3.64 ± 0.21g/dL in January 2017 and 3.64 ± 0.23g/dL in December 2017, without significant change. Typical cases: 1) A case with itchiness: HDF was performed at β2-MG and α1-MG removal rates of 77% and 30%, respectively. The patient developed strong itching. The symptom disappeared after performing HDF, at the α1-MG removal rate of 43%. 2) A case with restless legs syndrome (RLS): Decreased efficiency of dialysis (α1-MG removal rate, 39%→30%) led to RLS with an International Restless Leg Syndrome Study Group Rating Scale score of 32. The symptom disappeared after performing HDF at the α1-MG removal rate of 42%. 3) A case with dialysis amyloidosis: Decreased efficiency of dialysis (α1-MG removal rate, 37%→30%) led to shoulder joint pain. The symptom greatly improved after HDF at the α1-MG removal rate of 38%.
CONCLUSIONS: Efficient removal of LMWP is always associated with Alb leakage. An Alb leakage of 3 to 6 g/session is within the acceptable range. α1-MG is the most appropriate marker of the removal efficiency of HDF.
Comments