Spurious overestimation of plasma cortisol in patients with chronic renal failure.

Plasma cortisol concentrations in patients with chronic renal failure were measured by five different RIAs, four commercial methods, and an in-house method after paper chromatography. It was observed that cortisol concentrations of the same samples measured by the various methods did not agree. The difference was attributed to cross-reactivity of the antisera with steroids and glucuronide conjugates which circulate at high concentrations in patients with chronic renal failure.