Disclosed are methods for determining efficacy of a cyclodextrin therapy in a subject afflicted with a disorder involving oxysterol accumulation. These methods comprise: obtaining a first body fluid sample from the subject prior to cyclodextrin administration; administering cyclodextrin; obtaining at least one second body fluid sample after the cyclodextrin administration; subjecting the body fluid samples to chromatography-mass spectroscopy analysis to determine concentration of 24-hydroxycholesterol and/or cholestane-3β,5α,6β-triol; and determining magnitude of difference between the 24-hydroxycholesterol and/or cholestane-3β,5α,6β-triol concentration of the body fluid samples, whereby an increase or stabilization of 24-hydroxycholesterol concentration, or a reduction of cholestane-3β,5α,6β-triol concentration in the at least one second sample compared to the first sample, indicates efficacy of the cyclodextrin therapy.