The present invention concerns methods and tools for analysing biomarkers useful for diagnosing an individual, in particular a newborn, with a respiratory disease, especially a newborn suffering from respiratory distress syndrome (RDS). The method and tools of the invention can in one embodiment be used for very rapidly detecting the ratio between lecithin and sphingomyelin in very small body fluid samples, e.g. gastric aspirate of a newborn. The invention is thus useful for obtaining a rapid treatment of RDS by administration of surfactant.
