Fiber-optic evanescent-wave spectroscopy for fast multicomponent analysis of human blood

A spectral analysis of human blood serum was undertaken by fiber-optic evanescent-wave spectroscopy (FEWS) by the use of a Fourier-transform infrared spectrometer. A special cell for the FEWS measurements was designed and built that incorporates an IR-transmitting silver halide fiber and a means for introducing the blood-serum sample. Further improvements in analysis were obtained by the adoption of multivariate calibration techniques that are already used in clinical chemistry. The partial least-squares algorithm was used to calculate the concentrations of cholesterol, total protein, urea, and uric acid in human blood serum. The estimated prediction errors obtained (in percent from the average value) were 6% for total protein, 15% for cholesterol, 30% for urea, and 30% for uric acid. These results were compared with another independent prediction method that used a neural-network model. This model yielded estimated prediction errors of 8.8% for total protein, 25% for cholesterol, and 21% for uric acid.     

Multivariate determination of glucose in whole blood by attenuated total reflection infrared spectroscopy

A spectral analysis of whole EDTA blood was undertaken by using attenuated total reflection and Fourier-transform infrared spectroscopy. The concentration of blood glucose was measured by an enzymatic method using glucose dehydrogenase and ranged between 40 and 290 mg/dL with an average concentration of 90.4 mg/dL. Multivariate calibration with the partial least-squares (PLS) algorithm was performed on spectral data between 1500 and 750 cm-1 showing a varying background from different unidentified interfering compounds. Cross validation was carried out for optimizing the PLS model. PRESS was 19.8 mg/dL, which was calculated on the basis of 127 standards, whereas the estimated standard deviation for the calibration fit was computed to be 11.9 mg/dL. Infrared spectroscopy can be used for monitoring glucose levels within the normal physiological range in a complex matrix like whole blood as an alternative to electrochemical sensors.     

Fiber-optic evanescent-wave spectroscopy and neural networks: application to chemical blood analysis

An infrared spectral analysis of human blood serum has been carried out with Fourier transform infrared fiber-optic evanescent-wave spectroscopy. The measured spectra were analyzed by neural network analysis to predict concentrations of cholesterol, creatinine, total protein, urea, and uric acid. The predicted concentrations were compared with results from standard chemical analysis of blood and a good correlation was observed.     

Poly (pyrrole-co-<Emphasis Type="Italic">N</Emphasis>-methyl pyrrole) for application to cholesterol sensor

Cholesterol oxidase (ChOx) has been electrochemically entrapped onto p-toluene sulphonate (PTS) doped poly (pyrrole-co-N-methyl pyrrole) (1:1) on indium-tin-oxide (ITO) glass plates. This ChOx-copolymer-PTS/ITO bioelectrode has been characterized using cyclic voltammetry (CV), Fourier transform infrared (FTIR) spectroscopy, UV-visible spectroscopy, scanning electron microscopy (SEM) techniques. The cholesterol bioelectrode shows response time of 19 s, linearity from 50 to 400 mg/dL as a function of cholesterol concentration. It exhibits optimum pH range between 6.5 and 7.5, shelf-life of up to 6 weeks at 4 °C and shows almost undisturbed response in presence of interferents like ascorbic acid, uric acid and glucose.     

Determination of glucose concentration from NIR spectra using independent component regression

In this paper, a new model based on independent component regression (ICR) is proposed to predict the glucose concentration from near infrared (NIR) spectra. The efficiency of the proposed model is validated using mixtures composed of glucose, urea and triacetin. The whole experiments were carried out in a non-controlled environment or sample conditions to show that the proposed model can suppress effectively most of the experimental variations. The proposed model decreases the standard error of prediction (SEP) from 35.59 mg/dL for Partial Least Square regression (PLS) and from 29.1 mg/dL for ICR to only 24.1 mg/dL.     

Glucose quantification in dried-down nanoliter samples using mid-infrared attenuated total reflection spectroscopy

The aim of this study was to determine the feasibility of minimally invasive glucose concentration measurement of a body fluid within the physiologically important range below 100 nL with a number of samples such as interstitial fluid, plasma, or whole blood using mid-infrared spectroscopy, but starting with preliminary measurements on samples of simple aqueous glucose solutions. The Fourier transform infrared spectrometer was equipped with a Golden Gate single reflection diamond attenuated total reflection (ATR) accessory and a room-temperature pyroelectric detector. As the necessary detection limits can be achieved only for dried samples within the spectrometric conditions realized by a commercial instrument, the work focused on the optimization of such ATR measurements. We achieved quantification of samples with volumes as low as 7 nL between 10 and 600 mg/dL. The standard error of prediction (SEP) for the concentration range 10-100 mg/dL is 3.2 mg/dL with full interval data between 1180 and 940 cm(-1). The performance of the prediction is given by a coefficient of variation of prediction (CV(pred) ) of 6.2%. When all samples within the whole concentration range are included, the SEP increases to 20.2 mg/dL, and hence the CV(pred) to 10.6% due to a nonlinear signal dependence on glucose concentration. A detection limit for glucose of 0.7 ng with a signal-to-noise ratio of 10 was obtained.     

Multiwalled carbon nanotube-based bi-enzyme electrode for total cholesterol estimation in human serum

This study aims at fabricating multiwalled carbon nanotubes (MWCNTs) based enzymatic bioelectrode for total cholesterol estimation in human serum. For this purpose, a gold (Au) electrode was modified with MWCNTs uniformly dispersed in nafion (Nf) matrix. Cholesterol oxidase (ChOx) and cholesterol esterase (ChEt) were immobilised onto this Nf–MWCNTs film-modified Au electrode using layer-by-layer technique to fabricate the final bioelectrodes. The immobilisation of ChOx and ChEt onto the electrodes was demonstrated by scanning electron microscopy. The fabricated bioelectrodes were electrochemically characterised using cyclic voltammetry. The bioelectrodes offer reliable response characteristics towards cholesterol and stable electrochemical properties in terms of extended linear response range of 0.080–0.950?mM, detection limit up to 0.01?mM and optimum storage stability up to three weeks. Experimental results reveal that the fabricated bioelectrode offer optimum repeatability and reproducibility towards the cholesterol estimation and can also efficiently exclude interference by the commonly coexisting ascorbic acid, uric acid, lactic acid, glucose and urea, which is favourable for its efficient use in the highly selective analysis of total cholesterol in serum samples.     

Lipid Metabolism and Cardiovascular Morbidity and Mortality in Hemodialysis Patients: Role of Factors Modulating Cytosolic Calcium

Animal studies indicate that insulin resistance and glucose intolerance leading to dyslipidemia in uremic rats are associated with increased cytosolic calcium ([Ca⁺⁺ i]). The resistance and intolerance are reversed with verapamil, but recur after its discontinuation. This finding suggests that hyperparathyroid‐induced [Ca ⁺⁺ i] increase is responsible for the metabolic derangement. We retrospectively examined, over a 12‐year period, the effects of factors that lower [Ca ⁺⁺i] on total serum cholesterol and triglycerides in 332 hemodialysis (HD) patients. Because the study was retrospective, detailed lipid profiles were not available. We therefore relied on morbidity and mortality outcomes related to atherosclerotic vascular disease. Patients with diabetes mellitus were excluded, because their dyslipidemia and vascular disease are mediated via a different mechanism. Four groups emerged: group I [high parathormone (PTH) in the absence of calcium channel blockers (CCBs), n = 107], representing the highest [Ca⁺⁺ i]; group II (high PTH in the presence of CCBs, n = 76) and group III (lower PTH in the absence of CCBs, n = 66), representing intermediate [Ca ⁺⁺ i]; and group IV (lower PTH in the presence of CCBs, n = 83) representing the lowest [Ca ⁺⁺i]. The theoretically lower [Ca ⁺⁺ i] was achieved via CCB therapy or lower PTH, or both. The mean serum cholesterol in group I was 322 ± 24 mg/dL and the level of triglycerides was 398 ± 34 mg/dL. Group II had mean serum cholesterol of 196 ± 16 mg/dL and triglycerides of 157 ± 17 mg/dL. Group III had a mean serum cholesterol of 202 ± 19 mg/dL and triglycerides of 160 ± 15 mg/dL. Group IV had a mean serum cholesterol of 183 ± 9 mg/dL and triglycerides of 94 ± 6 mg/dL. The differences in cholesterol and triglyceride levels among four groups were significant (p < 0.001) by one‐way analysis of variance (ANOVA). The incidence of cardiovascular morbidity and mortality events was 61% in group I, 24% in group II, 28% in group III, and 18% in group IV (χ ² = 47.7, p < 0.001). We conclude that, in non diabetic HD patients, hyperparathyroidism, especially in the absence of CCBs, is associated with severe dyslipidemia and increased risk of cardiovascular morbidity and mortality. Dyslipidemia may be related to a hyperparathyroid‐induced increase in cytosolic calcium [Ca⁺⁺i]. Lowering [Ca⁺⁺i] by decreasing PTH or by blocking calcium entry into cells (via CCBs), or both, is associated with less dyslipidemia and improved long‐term cardiovascular morbidity and mortality. Prospective randomized studies, with actual measurement of [Ca ⁺⁺i], are needed to verify the results of this study.     

Determination of glucose in human aqueous humor using Raman spectroscopy and designed-solution calibration

Glucose concentrations of in vitro human aqueous humor (HAH) samples from cataract patients were determined using 785 nm Raman spectra and partial least squares (PLS) calibration. PLS models were created from spectra of prepared calibration solutions rather than aqueous humor samples. Spectra were obtained with an excitation energy (100 mW for 150 s), which was higher than can be applied in vivo, to decrease the models' contribution to prediction uncertainty. The solutions contained experimentally designed levels of glucose, bicarbonate, lactate, urea, and ascorbate. Multiplicative signal correction of spectra helped compensate for the +/-20% drift in laser power observed at the sample over six noncontiguous days of data collection. Seventeen HAH samples containing 38-775 mg/dL of glucose exhibited a root-mean-square error (RMSEP) of 22 mg/dL, coefficient of determination (r(2)) of 0.989, and bias of 6 mg/dL when predicted from lower energy (30 s) spectra collected contemporaneously with fifty calibration spectra. Similar results were obtained even when spectral data were gathered separately for human aqueous humor samples and calibration samples: 10 HAH samples, calibrated on 25 solutions measured 3.6 weeks earlier, exhibited an RMSEP of 23 mg/dL, r(2) of 0.992, and bias of 9 mg/dL. The results demonstrate progress toward the determination of glucose levels in patient-derived aqueous humor using laboratory-derived "artificial aqueous humor" calibration solutions.     

Real-time glucose sensing by surface-enhanced Raman spectroscopy in bovine plasma facilitated by a mixed decanethiol/mercaptohexanol partition layer

A new, mixed decanethiol (DT)/mercaptohexanol (MH) partition layer with dramatically improved properties has been developed for glucose sensing by surface-enhanced Raman spectroscopy. This work represents significant progress toward our long-term goal of a minimally invasive, continuous, reusable glucose sensor. The DT/MH-functionalized surface has greater temporal stability, demonstrates rapid, reversible partitioning and departitioning, and is simpler to control compared to the tri(ethylene glycol) monolayer used previously. The data herein show that this DT/MH-functionalized surface is stable for at least 10 days in bovine plasma. Reversibility is demonstrated by exposing the sensor alternately to 0 and 100 mM aqueous glucose solutions (pH approximately 7). The difference spectra show that complete partitioning and departitioning occur. Furthermore, physiological levels of glucose in two complex media were quantified using multivariate analysis. In the first system, the sensor is exposed to a solution consisting of water with 1 mM lactate and 2.5 mM urea. The root-mean-squared error of prediction (RMSEP) is 92.17 mg/dL (5.12 mM) with 87% of the validation points falling within the A and B range of the Clarke error grid. In the second, more complex system, glucose is measured in the presence of bovine plasma. The RMSEP is 83.16 mg/dL (4.62 mM) with 85% of the validation points falling within the A and B range of the Clarke error grid. Finally, to evaluate the real-time response of the sensor, the 1/e time constant for glucose partitioning and departitioning in the bovine plasma environment was calculated. The time constant is 28 s for partitioning and 25 s for departitioning, indicating the rapid interaction between the SAM and glucose that is essential for continuous sensing.     

A fluorescence-based glucose biosensor using concanavalin A and dextran encapsulated in a poly(ethylene glycol) hydrogel.

A fluorescence biosensor is described that is based on a photopolymerized poly(ethylene glycol) (PEG) hydrogel incorporating fluorescein isothiocyanate dextran (FITC-dextran) and tetramethylrhodamine isothiocyanate concanavalin A (TRITC-Con A) chemically conjugated into the hydrogel network using an alpha-acryloyl, omega-N-hydroxysuccinimidyl ester of PEG-propionic acid. In the absence of glucose, TRITC-Con A binds with FITC-dextran, and the FITC fluorescence is quenched through fluorescence resonance energy transfer. Competitive glucose binding to TRITC-Con A liberates FITC-dextran, resulting in increased FITC fluorescence proportional to the glucose concentration. In vitro experiments of hydrogel spheres in a solution of 0.1 M phosphate-buffered saline (pH 7.2) and glucose were conducted for multiple TRITC-Con A/FITC-dextran ratios. Hydrogels were characterized on the basis of the percent change in fluorescence intensity when FITC-dextran was liberated by increasing glucose concentrations. The optimum fluorescent change between 0 and 800 mg/dL was obtained with a TRITC-Con A/FITC-dextran mass ratio of 500:5 micrograms/mL PEG. Fluorescent response was linear up to 600 mg/dL. At higher concentrations, the response saturated due to the displacement of the majority of the FITC-dextran and to concentration quenching by free FITC-dextran. Dynamic fluorescent change upon glucose addition was approximately 10 min for a glucose concentration step change from 0 to 200 mg/dL.     

Long-Term Transport Study of Bioartificial Tubule Devices in the Development of a Bioartificial Kidney

Introduction: A bioartificial kidney, which consists of a continuous hemofilter and a bioartificial tubule device using proximal tubular epithelial cells (LLC‐PK₁), is desired to develop for preventing long‐term complications in hemodialysis patients. A bioartificial tubule device should function for a long duration in terms of the simplicity and the economy. Continuous hemofiltration with 10 L/day of filtrate could maintain plasma urea, creatinine and β₂‐microglobulin in patients at low levels compared to those in standard hemodialysis patients. Methods: 6 bioartificial tubule devices, in which LLC‐PK₁ cells were grown on the inner surfaces of hollow fiber capillaries (membrane area: 0.4 m², 1600 fibers), were used to evaluate the transport ability of H₂O, glucose and Na⁺, and leak rates of urea and creatinine for 2 weeks when the medium containing 50 mg/dL of urea and 5.0 mg/dL of creatinine was perfused inside of the cell‐attached membranes and another medium containing 2.5 g/dL of albumin was perfused outside of the membranes. Scanning electron micrograph of cross‐sectional findings of the hollow fibers was taken at 6, 10, and 14 days after formation of confluence. Results: By conversion into 1 m² of membrane area, transport of H₂O, glucose, and Na⁺ was 6266 ± 995 mL/day, 22832 ± 7240 mg/day, and 941.3 ± 180 mEq/day, respectively at 6 days after confluence. Leak rates of urea and creatinine across the cell‐attached membranes were 22 ± 6.1% and 19.2 ± 4.9 with albumin addition, whereas 13.1 ± 1.9% and 12.2 ± 1.6 without albumin addition. Transport capacity of these components and the leak rates had continued for 10–13 days, and decreased thereafter because of the formation of the multilayers. Bioartificial tubule devices with membrane area 1.0 m² can reach the targeted amounts of H₂O, glucose, and Na⁺ transports when 6 L of 10 L/day of hemofiltrate has to be regenerated, substituting 4 L with meal and drinks.     

Infrared transmission spectrometry for the determination of urea in microliter sample volumes of blood plasma dialysates

Application of mid-infrared spectroscopy for the determination of urea in blood plasma dialysates of microliter sample volumes using a transmission microcell was investigated. Infrared spectra of the dialysates of plasma samples collected from 75 different patients using CMA 60 microdialysis catheters were evaluated with multivariate partial least squares regression. Using the absorbance spectral data from 1520-1420 cm(-1) and 1220-1120 cm(-1), a minimum standard error of prediction (SEP) of 0.88 mg/dL (0.14 mM) was achieved with spectral variable selection. Our findings suggest the feasibility of developing a mid-infrared sensor in combination with micro-fluidics for on-line monitoring of urea in patients undergoing dialysis treatment.     

Assessing lipid lowering and plasma cholesteryl ester transfer protein activity of simvastatin following administration to rabbits fed a high fat/cholesterol diet

Purpose: The purpose of this study was to assess the lipid lowering and plasma cholesteryl ester transfer protein (CETP) activity following administration of simvastatin to rabbits fed a high fat/cholesterol diet. Methods: Male New Zealand white rabbits were housed in individual cages and fed a standard diet for 7 days. After 7 days, animals were fed 10 g of a regular chow diet plus 100 g of the same diet supplemented with 0.5% (w/v) cholesterol and 14.0% (w/v) coconut oil for 28 days. Following 28 days on this diet, the animals were randomized based on plasma cholesterol and triglyceride levels, into a group of control animals and a group (n = 6) of animals fed 100 g of cholesterol/coconut diet plus 10 g regular chow diet containing simvastatin (3 mg/kg/day) for an additional 28 days. Blood samples were taken from the marginal ear vein prior to and 28 days after the initiation of drug treatment. Plasma was harvested and stored at 4°C prior to lipid analysis. Plasma total cholesterol and triglyceride levels were quantified using enzymatic kits. HDL (high-density lipoproteins) cholesterol levels were determined using the dextran sulfate-Mg²⁺ precipitation method. ApoB cholesterol levels were determined by subtracting total cholesterol from HDL cholesterol. Cholesteryl ester transfer protein (CETP) activity was determined by standard assay methods. Results: We observed that simvastatin significantly reduced total plasma cholesterol, triglyceride, and apoB cholesterol compared to non-treated controls. Simvastatin treatment did not alter serum CETP activity compared to non-treated controls. Conclusions: These findings suggest that decreasing plasma lipid levels by treatment with simvastatin is not due to changes in serum CETP activity in rabbits fed a high fat/cholesterol diet.     

Effects of flaxseed consumption on systemic inflammation and serum lipid profile in hemodialysis patients with lipid abnormalities

Inflammation and lipid abnormalities are two important risk factors for cardiovascular disease in hemodialysis (HD) patients. The present study was designed to investigate the effects of flaxseed consumption on systemic inflammation and serum lipid profile in HD patients with lipid abnormalities. This was an unblinded, randomized clinical trial. Thirty HD patients with dyslipidemia (triglyceride >200 mg/dL and/or high‐density lipoprotein‐cholesterol (HDL‐C) <40 mg/dL) were randomly assigned to either a flaxseed or control group. Patients in the flaxseed group received 40 g/day ground flaxseed for 8 weeks, whereas patients in the control group received their usual diet, without any flaxseed. At baseline and at the end of week 8, 7 mL of blood was collected after a 12‐ to 14‐hour fast and serum concentrations of triglyceride, total cholesterol, low‐density lipoprotein‐cholesterol (LDL‐C), HDL‐C, and C‐reactive protein (CRP) were measured. Serum concentrations of triglyceride (P < 0.01), total cholesterol (P < 0.01), LDL‐C (P < 0.01), and CRP (P < 0.05) decreased significantly in the flaxseed group at the end of week 8 compared with baseline, whereas serum HDL‐C showed a significant increase (P < 0.01). These changes in the flaxseed group were significant in comparison with the control group. The study indicates that flaxseed consumption improves lipid abnormalities and reduces systemic inflammation in HD patients with lipid abnormalities.     

Middle infrared, quantum cascade laser optoelectronic absorption system for monitoring glucose in serum

Advances in middle infrared technology are leading researchers beyond the Fourier transform infrared spectrometer and to the quantum cascade laser. While most research focuses on gas-phase detection, recent research explores its use for condensed-phase matter studies. This work investigates its use for monitoring biologically relevant samples of glucose in serum. Samples with physiological glucose concentrations were monitored with a laser at 1036 cm-1. A 0.992 R2 linearity value was observed. In addition, using another laser at 1194 cm-1 as a measure of the background spectroscopic characteristics, a linearity of 0.998 R2 was observed. The average predictive standard errors of the mean (SEM) were 32.5 and 24.7 mg/dL, respectively, for each method. Quantum cascade lasers could be used to develop middle infrared devices for uses beyond the confines of the laboratory.     

Assessing Lipid Lowering and Plasma Cholesteryl Ester Transfer Protein Activity of Simvastatin Following Administration to Rabbits Fed a High Fat/Cholesterol Diet

ABSTRACT

Purpose: The purpose of this study was to assess the lipid lowering and plasma cholesteryl ester transfer protein (CETP) activity following administration of simvastatin to rabbits fed a high fat/cholesterol diet. Methods: Male New Zealand white rabbits were housed in individual cages and fed a standard diet for 7 days. After 7 days, animals were fed 10 g of a regular chow diet plus 100 g of the same diet supplemented with 0.5% (w/v) cholesterol and 14.0% (w/v) coconut oil for 28 days. Following 28 days on this diet, the animals were randomized based on plasma cholesterol and triglyceride levels, into a group of control animals and a group (n = 6) of animals fed 100 g of cholesterol/coconut diet plus 10 g regular chow diet containing simvastatin (3 mg/kg/day) for an additional 28 days. Blood samples were taken from the marginal ear vein prior to and 28 days after the initiation of drug treatment. Plasma was harvested and stored at 4°C prior to lipid analysis. Plasma total cholesterol and triglyceride levels were quantified using enzymatic kits. HDL (high-density lipoproteins) cholesterol levels were determined using the dextran sulfate-Mg²⁺ precipitation method. ApoB cholesterol levels were determined by subtracting total cholesterol from HDL cholesterol. Cholesteryl ester transfer protein (CETP) activity was determined by standard assay methods. Results: We observed that simvastatin significantly reduced total plasma cholesterol, triglyceride, and apoB cholesterol compared to non-treated controls. Simvastatin treatment did not alter serum CETP activity compared to non-treated controls. Conclusions: These findings suggest that decreasing plasma lipid levels by treatment with simvastatin is not due to changes in serum CETP activity in rabbits fed a high fat/cholesterol diet.     

In vivo, transcutaneous glucose sensing using surface-enhanced spatially offset Raman spectroscopy: multiple rats, improved hypoglycemic accuracy, low incident power, and continuous monitoring for greater than 17 days

This paper presents the latest progress on quantitative, in vivo, transcutaneous glucose sensing using surface enhanced spatially offset Raman spectroscopy (SESORS). Silver film over nanosphere (AgFON) surfaces were functionalized with a mixed self-assembled monolayer (SAM) and implanted subcutaneously in Sprague-Dawley rats. The glucose concentration was monitored in the interstitial fluid of six separate rats. The results demonstrated excellent accuracy and consistency. Remarkably, the root-mean-square error of calibration (RMSEC) (3.6 mg/dL) and the root-mean-square error of prediction (RMSEP) (13.7 mg/dL) for low glucose concentration (<80 mg/dL) is lower than the current International Organization Standard (ISO/DIS 15197) requirements. Additionally, our sensor demonstrated functionality up 17 days after implantation, including 12 days under the laser safety level for human skin exposure with only one time calibration. Therefore, our SERS based sensor shows promise for the challenge of reliable continuous glucose sensing systems for optimal glycemic control.     

Vertically aligned carbon nanotube probes for monitoring blood cholesterol

Detection of blood cholesterol is of great clinical significance. The amperometric detection technique was used for the enzymatic assay of total cholesterol. Multiwall carbon nanotubes?(MWNTs), vertically aligned on a silicon platform, promote heterogeneous electron transfer between the enzyme and the working electrode. Surface modification of the MWNT with a biocompatible polymer, polyvinyl alcohol?(PVA), converted the hydrophobic nanotube surface into a highly hydrophilic one, which facilitates efficient attachment of biomolecules. The fabricated working electrodes showed a linear relationship between cholesterol concentration and the output signal. The efficacy of the multiwall carbon nanotubes in promoting heterogeneous electron transfer was evident by distinct electrochemical peaks and higher signal-to-noise ratio as compared to the Au electrode with identical enzyme immobilization protocol. The selectivity of the cholesterol sensor in the presence of common interferents present in human blood, e.g.?uric?acid, ascorbic acid and glucose, is also reported.     

Kinetics, dialysis systems, adequacy Postdialysis rebound in a case of acute methanol poisoning

Introduction:  Methanol poisoning can lead to complications that include metabolic acidosis, visual impairment and death. Treatment options include ethanol, fomepizole, and hemodialysis (HD). Objective:  To report on the occurrence of post dialysis methanol rebound during treatment. Method and Findings:  A 40‐year‐old male with a history of schizophrenia and suicide attempts presented to the emergency room after reportedly ingesting 1 quart of windshield washer fluid. The patient presented with a preliminary blood chemistry of methanol 390 mg/dL, ethanol 48 mg/dL, glucose 93 mg/dL, Na 138 meq/L, K 3.8 meq/L, Cl 98 mmol/L, CO₂ 26 mmol/L, urea 16 mg/dL, creatinine 1.2 mg/dL, and an anion gap of 14 mmol/L. The patient was started on 1360 mg of fomepizole (12:50 AM) followed by HD for 4 hours. A second dose of fomepizole (900 mg) was administered at 8:00 AM. In addition, another HD session was started at 12:00 PM and continued for 4 hours. A third dose of fomepizole (700 mg) was administered at 8:50 PM. Finally, a third HD session was started the next day at 3:05 PM and lasted 3 hours. Table 1 illustrates methanol levels in relation to each HD session. Findings:  Methanol concentration after the first HD increased from 100 mg/dL to 127 mg/dL (27%) in 5 h 20 m. It also increased from 35 mg/dL to 50 mg/dL (43%) 14 h 45 m after the second HD. Conclusions:  Close attention must be paid to the potential for post dialysis methanol rebound. It is recommended that methanol levels continue to be monitored for several hours after HD.  

  Table 1   Methanol levels before and after each hemodialysis