OBJECTIVE: To evaluate commercially available determination methods for HbA1c in patients with hemoglobin variants. RESEARCH DESIGN AND METHODS: HbA1c values were determined with various commercially available methods, including ion-exchange high-performance liquid chromatography (HPLC), boronate affinity assay, and immunoagglutination in patients with the hemoglobin mutations Hb Graz, Hb Sherwood Forest, Hb O Padova, Hb D, and Hb S. RESULTS: The effect of hemoglobinopathies on glycohemoglobin measurements was highly method dependent. The HPLC methods for HbA1c determination lacked the resolution necessary to differentiate hemoglobin variants. They demonstrated additional peaks in the chromatograms and HbA1c results either too low or too high compared with the nondiabetic reference range. With all immunoassays, Hb Graz demonstrated falsely low values. The other hemoglobinopathies in our study caused falsely low and/or high HbA1c results in immunoagglutination methods. The boronate affinity method showed values in an acceptable range for all hemoglobin variants. CONCLUSIONS: Because of the local occurrence of Hb variants and the ethnic origin of a given population, every individual laboratory must establish and validate its own assay method. In managing diabetic patients, knowledge of hemoglobinopathies influencing HbA1c determination methods is essential because hemoglobin variants could cause mismanagement of diabetes resulting from false HbA1c determinations.

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IntroductionPositional therapy is a simple means of therapy in sleep apnoea syndrome, but due to controversial or lacking evidence, it is not widely accepted as appropriate treatment. In this study, we analysed data to positional therapy with regard to successful reduction of AHI and predictors of success.MethodsAll consecutive patients undergoing polysomnography between 2007 and 2011 were analysed. We used a strict definition of positional sleep apnoea syndrome (supine-exclusive sleep apnoea syndrome) and of therapy used. Patients underwent polysomnography initially and during follow-up.Results1275 patients were evaluated, 112 of which had supine-exclusive sleep apnoea syndrome (AHI 5-66/h, median 13/h), 105 received positional therapy. With this treatment alone 75% (70/105) reached an AHI <5/h, in the follow-up 1 year later 37% (37/105) of these still had AHI<5/h, 46% (43/105) yielded an AHI between 5 and 10/h. Nine patient switched to APAP due to deterioration, 3 wanted to try APAP due to comfort reasons. At the last follow-up, 32% patients (34/105) were still on positional therapy with AHI <5/h. BMI was a predictor for successful reduction of AHI, but success was independent of sex, the presence of obstructive versus central sleep apnoea, severity of sleep apnoea syndrome or co-morbidities.ConclusionPositional therapy may be a promising therapy option for patients with positional sleep apnoea. With appropriate adherence it yields a reasonable success rate in the clinical routine.

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