Unexpected hemoglobin A results after an erythrocyte exchange: importance of specimen mixing.

proved by the local ethics committee. Compared to the healthy controls, median concentrations of cholesten (interquartile range) in patients with ileal resection were significantly higher [87.8 g/L (range 42.1–150.5 g/L) vs 11.9 g/L (range 9.2–16.9 g/L), P 0.001, Mann–Whitney RankSum test]. This method retains the advantages of other HPLC-based methods, while eliminating the need for temperature-controlled SPE. Silica cartridges offer higher binding capacity and the possibility of analyte extraction at ambient temperature, which, compared to previously used C8 cartridges, results in a wider linear range (up to 1000 g/L vs 200 g/L) (4). Except for the chloroform:methanol extraction, the analysis can theoretically be automated. Additionally, the initial chloroform:methanol extraction ensures quantitative extraction of both cholesten and the internal standard and thus potential imprecision caused by either internal standard precipitation or incomplete extraction of protein-bound cholesten can be avoided. The increased availability of a laboratory diagnosis of bile acid malabsorption is of considerable importance, especially for patients with chronic diarrhea and irritable bowel syndrome. These disorders belong to the most common gastrointestinal conditions, and it is estimated that bile acid malabsorption might be present in about half of these patients (5). Because the majority of patients wit bile acid malabsorption respond to bile acid sequestrants (5), targeted therapy, based on serum cholesten concentrations, should both improve outcomes and lower treatment costs.