Biological variation of glycohemoglobin.

The high precision of the results may enable single measurements instead of multiple determination, thereby reducing costs. The significantly lower values for ghrelin in citrate plasma may only partially (ϳ12%) be explained by dilution with the anticoagulating liquid in the tubes (118 Ϯ 15 ␮L). The discrepancy between citrate plasma and serum was ϳ25%, a discrepancy that is too high for a recommendation for citrate plasma. In contrast, results for lithium-heparinate plasma were in only ϳ7% lower than serum results, which we consider to acceptable. It should be kept in mind that the magnitude of the difference between values from matched sample matrices might be influenced by the assay system used, as has been shown for the determination of cardiac troponin T and I (14, 15). Our findings are based on the use of a direct RIA that is commercially available and is currently widely used for research. As we have determined, storage of serum under cooled conditions allows stable results for up to 3 days. Storage at warm temperatures for Ͼ1 day should be avoided. This is very important when samples are transported by mail. Because no significant decrease in the ghrelin values was observed after repeated freezing and thawing, there should be no problems if sample tubes are used several times, e.g., for repeating an assay or using material after determination of other analytes. In conclusion, ghrelin is relatively stable when stored under cooled conditions. This, as well as the fact that several sample matrices can be used as alternatives, is a good precondition for further studies on this interesting peptide hormone. discovery of the natural endogenous ligand for the growth hormone secretagogue receptor. a natural GH secretagogue produced by the stomach, induces hyperglycemia and reduces insulin secretion in humans. Plasma ghrelin levels in lean and obese humans and the effect of glucose on ghrelin secretion. Effect of duration and temperature of storage on serum analyte stability: examination of 14 selected radioimmunoassay procedures. al. Lower cardiac troponin T and I results in heparin-plasma than in serum. al. Troponin T and I assays show decreased concentrations in heparin plasma compared with serum: lower recoveries in early than in late phases of myocardial injury. Glycohemoglobin (GHb) is a measure of long-term mean glycemia that predicts risks for the development and/or progression of diabetic complications in patients with type 1 and type 2 diabetes (1, 2). Several reports have suggested, however, …