Plasma Levels of Biotin Metabolites Are Elevated in Hemodialysis Patients with Cramps.

Patients with renal failure undergoing hemodialysis (HD) are susceptible to muscle cramps during and after HD. Muscle cramps are defined as the sudden onset of a prolonged involuntary muscle contraction accompanied by severe pain. Through HD, water-soluble vitamins are drawn out with water. Since biotin, a water-soluble vitamin, plays an essential role as one of the coenzymes in producing energy, we have hypothesized that deficiency of biotin may be responsible for HD-associated cramps. We previously reported that biotin administration ameliorated the muscle cramps, despite the elevated plasma biotin levels before HD and biotin administration, as judged by an enzyme-linked immunosorbent assay (ELISA). However, the ELISA measures not only biotin but also total avidin-binding substances (TABS) including biotin metabolites. In the present study, we determined biotin in HD patients as well as healthy controls, using a newly developed method with ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). The plasma samples were collected from 28 HD patients (16 patients with cramps and 12 patients without cramps) before HD and biotin administration and from 11 controls. The results showed that the accumulation of biotin and TABS in plasma of HD patients compared to controls. Importantly, the levels of biotin metabolites, i.e. TABS subtracted by biotin, increased significantly in patients with cramps over those without cramps. Moreover, the levels of biotin metabolites were significantly higher in patients with a poor response to administered biotin, compared to those with a good response. We propose that accumulated biotin metabolites impair biotin's functions as a coenzyme.

A simple and rapid ultra-high-performance liquid chromatography-tandem mass spectrometry method to determine plasma biotin in hemodialysis patients.

A simple, rapid, and selective method for determination of plasma biotin was developed using ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). After single-step protein precipitation with methanol, biotin and stable isotope-labeled biotin as an internal standard (IS) were chromatographed on a pentafluorophenyl stationary-phase column (2.1 × 100 mm, 2.7 µm) under isocratic conditions using 10 mm ammonium formate-acetonitrile (93:7, v/v) at a flow rate of 0.6 mL/min. The total chromatographic runtime was 5 min for each injection. Detection was performed in a positive electrospray ionization mode by monitoring selected ion transitions at m/z 245.1/227.0 and 249.1/231.0 for biotin and the IS, respectively. The calibration curve was linear in the range of 0.05-2 ng/mL using 300 µL of plasma. The intra- and inter-day precisions were all <7.1%. The accuracy varied from -0.7 to 8.2%. The developed UHPLC-MS/MS method was successfully applied to determine plasma biotin concentrations in hemodialysis patients. Copyright © 2016 John Wiley & Sons, Ltd.

Metabolic responses during hemodialysis determined by quantitative (1)H NMR spectroscopy.

A large proportion of patients with end-stage renal disease have lifelong hemodialysis (HD) treatment. HD rapidly and indiscriminately removes necessary small metabolites together with uremic toxins from plasma into dialysate. To investigate metabolic responses to HD, we determined the levels of metabolites through time-course monitoring of (1)H NMR spectroscopy of dialysate during HD. The dialysate sample is stable for analysis because it contains only small metabolites without proteins. It was collected non-invasively from 9 HD patients with chronic glomerular nephropathy, at 6 time points during 4h of HD in 5 sessions. Creatinine, alanine, lactate, pyruvate and valine were simultaneously quantified on a one-dimensional single-pulse spectrum with a single standard compound. The concentration of creatinine exhibited monotonous decay with time, while that of valine decreased slowly and then maintained its levels throughout an HD. Lactate, alanine and pyruvate increased at 2-3h after the initiation of HD. They exhibited remarkable responses to HD with production from the body. The time-course of change in the 4 metabolites of lactate, pyruvate, alanine, and valine had reproducible behavior unique to each patient during the HD. This finding may be applied to distinguish metabolic status in HD patients.

¹H NMR spectroscopic quantification of plasma metabolites in dialysate during hemodialysis.

We used ¹H nuclear magnetic resonance (NMR) spectroscopy to assess metabolic responses in patients undergoing hemodialysis (HD). We collected 71 samples of plasma and dialysate from 10 patients before, during, and after HD. We used the dialysate as a possible substitute for blood plasma to quantify small metabolites by ¹H NMR. We confirmed TSP (sodium 3-(trimethylsilyl) propionate 2, 2, 3, 3-d4) as a reference of NMR intensity in dialysate. We examined TSP sensitivities in various dialysate spectra and the correlation between signal intensities and added quantities of TSP. We used integrations of signal areas on ¹H NMR spectra of plasma and dialysate to quantify concentrations of creatinine, lactate, alanine, and valine and calculate their ratios between plasma and dialysate. The ratios of metabolites in plasma to dialysate were 3.2±0.4 (creatinine), 3.6±0.5 (valine), 3.8±0.7 (alanine), and 4.0±0.8 (lactate) mM (mean±standard deviation [SD]). The broader distributions of ratios in levels of lactate and alanine suggested their de novo production during the HD session. Estimation of blood metabolite levels using dialysate is useful for quantitative analysis of metabolic status in blood during HD.

Biotin ameliorates muscle cramps of hemodialysis patients: a prospective trial.

Patients with renal failure undergoing hemodialysis often have muscle cramps during and after the dialysis therapy. Muscle cramps are defined as the sudden onset of a prolonged involuntary muscle contraction accompanied with severe pain, resulting in early termination of a HD session and inadequate dialysis. The etiology of the cramps is unknown and effective anti-cramp medicine is not available. We have hypothesized that water-soluble vitamins are deficient in HD patients. Accordingly, we administrated biotin to 14 patients who had frequent muscle cramps during HD sessions. Oral administration of 1 mg/day biotin promptly reduced the onset and the severity of cramps in 12 patients both during and after HD. Then, the plasma biotin levels were measured by an enzyme-linked immunosorbent assay method (ELISA) in HD patients, including 14 patients with cramps and 13 patients without cramps, and 11 healthy volunteers. Plasma biotin levels were elevated in 27 HD patients at baseline compared with healthy volunteers [451 (377 - 649) vs. 224 (148 - 308) ng/l, median (lower-upper quartiles); p < 0.0001]. Unexpectedly, among the 14 cramp patients, the biotin levels were significantly higher in biotin-ineffective 7 patients than biotin-effective 7 patients [1,064 (710 - 1,187) vs. 445 (359 - 476) ng/l; p < 0.001]. Thus, the biotins measured by ELISA may consist of not only intact biotin but also its metabolites that do not function as a vitamin. In conclusion, biotin administration is one choice to relieve HD patients from muscle cramps regardless of their elevated plasma biotin levels.