Establishing reference intervals for NMR spectra in human plasma
D. Rosenkranz (Oldenburg, DE)
Reference intervals are an important tool for the clinical interpretation of laboratory results. The usual approach for establishing reference intervals implies the calculation of designated percentiles after the measurement of a single measurand in a defined “healthy” reference population. For multi-measurand determinations within one analytical run, e.g. from NMR spectra, the calculation of reference intervals becomes more complex and is not well established.
Material and Methods
In this work, 600 MHz NMR spectra from approximately 400 human plasma samples out of the study of health in Pomerania (SHIP) serve as the data base for the calculation of a reference spectrum. The NMR-measurement provides 4000 measuring points per spectrum, which refers to a spectral resolution of 0.0025 ppm (1.5 Hz). Percentiles of intensities are calculated at each measuring point and the reference spectrum is depicted as color-coded intensities. At this time point, no disease-specific exclusions were applied, so that the results are preliminary.
Results and Discussion
The established reference spectrum represents the distribution of the intensity of a given ppm across a large population. The intensity percentiles at a given ppm are color-coded, so that we are able to describe regions at the spectra which are uniform up to regions, which are very variable between participants.
According to the high standardization and comparability of the NMR spectra in human plasma samples, reference spectra are needed, to improve the medical value of this technology in the health care setting. Here we show a first approach to calculate a reference spectrum out of a large epidemiological study for plasma, measured by NMR spectroscopy.