Carbamylated Haemoglobin, Urea Kinetic Modelling and Adequacy of Dialysis in Haemodialysis Patients

Abstract

Urea kinetic modelling (UKM) has increasingly been used for assessing adequacy of dialysis and protein nutritional status of dialysis patients. Using a precise HPLC method we developed, we measured carbamylated haemoglobin (CarHb) values in 20 stable twice-weekly dialysed patients and attempted to correlate their CarHb values with their UKM-derived indices. Based on these indices, 11 patients were found to have been adequately dialysed with sufficient protein intake, three patients were adequately dialysed but malnourished and six patients were under-dialysed. Estimated dietary protein intake correlated poorly with calculated daily protein catabolic rate in our patients. CarHb values were found to correlate strongly with the time-averaged urea concentrations, suggesting that CarHb might be a time-integrated urea-derived index. Those adequately dialysed patients have a mean (SD) CarHb value of 142 (29) micrograms CV/gHb against the underdialysed patients, 197 (30) micrograms CV/gHb (t-test, P = 0.002). We suggest that a CarHb value less than 175 micrograms CV/gHb may represent satisfactory uraemic exposure, whereas CarHb value greater than 175 micrograms CV/gHb is undesirable.

Carbamylated Hemoglobin as a Therapeutic Marker in Hemodialysis

“…where C1, C2 and C3, respectively, represent the pre-BUN, the post-BUN and the pre-BUN at the next HD (mg/dl); t d represents duration of dialysis (min), and t o represents the interdialytic period (min) [11]. The nPCR value was determined by the method of Depner and Cheer [12].…”

Correction formula for carbamylated haemoglobin in diabetic uraemic patients

“…15 Carbamylated haemoglobin provides a greater intra-patient stability in the assessment of uraemia that is not affected by a single haemodialysis treatment, and takes some 2 weeks or more to decline following successful renal allograft transplantation. 18 It has a possible role in the clinical management of patients with chronic renal failure similar to the way glycosylated haemoglobin is used in the monitoring of diabetic patients. 15 Because both carbamylation and glycation reactions involve the free amino groups of the protein, especially the terminal valine residues in the case of haemoglobin, one should consider the possible interference between the two reactions.…”

Carbamylated Proteins and Peptides in Health and in Uremia

“…Stim et al [20], using HPLC – in contradistinction to Smith et al [4] who used gas chromatography – found a mean of 106 (SD 7) in hemodialysis patients. Kwan et al [21] reported the results in 20 patients; they divided their patients according to the adequacy of their dialyses and found in 11 with adequate dialysis that carbamylated hemoglobin was elevated (142 ± 29 µg of valine hydantoin per gram of hemoglobin), but in 6 of the underdialyzed group on hemodialysis the concentration was significantly higher (197 ± 30; p = 0.002). We have found in a group of adequately dialyzed hemodialysis patients, in whom the incubation was done at a carefully controlled 90°C, an elevated figure (89.6 ± 22) but lower than the values of Kwan et al [7], although our controls at this temperature were similar in value [Berlyne and Caruso, unpubl.…”

“…Davenport et al [12] studied 55 regular dialysis patients and like Kwan et al [21] found elevated carbamylated hemoglobin levels in both well-dialyzed and poorly dialyzed patients (120 ± 8 vs. 99 ± 7; p < 0.01).…”

“…Both Kwan et al [21] and Davenport et al [12] showed that in hemodialyzed patients adequacy of dialysis was inversely related to the carbamylated hemoglobin concentration. Davenport et al [12] pointed out that carbamylated hemoglobin was a useful marker of uremia, and it appears that carbamylated hemoglobin is a rather expensive and less accurate index of the time-averaged urea concentration.…”