below limit-of-quantification (loq) means that the concentration of the given biomarker is smaller than the range where the nightingale platform offers highly accurate quantification. for instance, the loq for lipoprotein lipid measures is < 0.01 mmol/l. the estimated biomarker concentration is reported for use in certain epidemiological analyses, but it may be advisable to conduct sensitivity analyses with all values below loq excluded.