I didn't check for availability on the lab site you have linked to, Muon, but I would certainly see some of these being tested, because they are elevated in MCAS ( Mast Cells Activation Syndrome):
tryptase,
N-methyl histamine,
prostaglandin D2 or 11-beta- prostaglandin F2 alpha,
leukotriene E4
Also, pro-inflammatory cytokines level would be interesting to test.
As noted by Romies in another thread, it is a problem that brain concentrations cannot be tested, otherwise, I would be very, very interested in checking kynurenine concentrations in brain during POIS, I would specifically like to know if quinolinic acid and kynurenic acid concentrations in the brain are up during POIS, since I believe they are responsible for the glutaminergic excitotoxicity , and respectively cognitive, and emotional symptoms, in POIS.