Blood-storage study finds 7-OH converts to pseudoindoxyl

Why it matters

Blood samples can change before a laboratory tests them. This forensic study shows why storage conditions and the compounds included in a test matter when interpreting suspected kratom-alkaloid exposures.

The big picture

Mitragynine in botanical kratom differs from the concentrated or semi-synthetic alkaloid products also sold under the kratom name. Researchers at the Center for Forensic Science Research and Education and NMS Labs developed a blood-testing method for four alkaloids and applied it to submitted forensic samples. These selected cases do not measure risk among kratom users generally or establish a fatal concentration.

Key findings

• The validated liquid chromatography–high-resolution mass spectrometry method measures mitragynine, 7-hydroxymitragynine (7-OH), mitragynine pseudoindoxyl and dihydro-7-hydroxymitragynine (MGM-15), while separating related chemical forms.
• In separately fortified human whole-blood samples stored at 4°C, 7-OH declined during 112 days of testing as pseudoindoxyl increased. This was a sample-storage experiment, not a measurement of metabolism in living people.
• Pseudoindoxyl remained comparatively stable over 112 days; mitragynine and MGM-15 did not decline by more than 20% over 84 days under the tested conditions.
• The method was applied to 205 authentic blood samples collected for forensic testing from October 2025 through May 2026. The authors reported separate 7-OH/pseudoindoxyl and MGM-15 case subsets.
• Concentrations alone may not identify which product was consumed. The authors call for case-specific interpretation using storage history, scene evidence and other findings, and recommend including pseudoindoxyl in testing.

What they say

The authors write that “case-by-case interpretation is still required” because concentrations vary widely and other factors matter when distinguishing botanical kratom from semi-synthetically enhanced products.

Bottom line

Testing several alkaloids and accounting for blood-sample storage can improve forensic interpretation; a detected compound alone does not establish the product used or the cause of death.