When the lab does a 'confirmatory second test,' is it on the same urine sample?

Yes — the confirmatory second analysis is performed on the same urine sample that you collected. The Yenos preservation media maintains specimen stability throughout the analysis period (several days at lab conditions), so the same collected specimen can be run twice on the MinION nanopore platform independently. This is important because it confirms that the elevation is real and reproducible in your specific biological sample — not an artifact of a single instrument run. You do not need to collect a second specimen. The second analysis is automatically initiated by the lab when any first-run marker exceeds the 1.5× HL threshold, at no additional charge.