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Table 1 Cortisol immunoassay cross-reactivity

From: Cross-reactivity of steroid hormone immunoassays: clinical significance and two-dimensional molecular similarity prediction

Compound Plasma/serum concentrations Cross-reactivity in Roche assay Likelihood of clinically significant cross-reactivity
Cortisol (endogenous compound) • 62 – 194 ng/mL (morning) [19] 100% High (assay target)
• 23 – 119 ng/mL (afternoon) [19]
6-Methylprednisolone Up to 1,000 ng/mL after oral or intravenous administration [20] 249% High
Allotetrahydrocortisol Unknown 165% (package insert) Unknown, serum/plasma concentrations not reported
6β-Hydroxycortisol Unknown 158% (package insert) Unknown, serum/plasma concentrations not reported
Prednisolone Up to 400 ng/mL in pediatric transplant patients [21] 148% High
21-Deoxycortisol • 0.28 – 0.43 ng/mL (pediatric controls) [22] 45.4% (package insert) Low, except in patients with 21-hydroxylase deficiency
• Up to 140 ng/mL (patients with 21-hydroxylase deficiency) [22]
Fludrocortisone • 0.36 ng/ml after single dose [23] 7.7% Low
5β-Dihydrocorticosterone Unknown 4.9% Unknown, serum/plasma concentrations not reported
Corticosterone • 0.18 – 2.0 ng/mL (18 years and younger) [24] 4.6% Low
• 0.53 – 1.6 ng/mL (<18 years) [24]
11-Deoxycortisol • 0.17 – 1.8 ng/mL (pediatric controls) [22] 4.6% Low, except in patients following metyrapone challenge or who have 11β-hydroxylase deficiency
• Up to 63 ng/mL (patients with 11β-hydroxylase deficiency) [22]
• Up to 250 ng/mL (following metyrapone challenge) [25]
Canrenone 10 – 1,000 ng/mL in patients receiving spironolactone [2628] 1.8% Low, except if cortisol measured during peak canrenone concentrations
17-Hydroxyprogesterone • 0.08 – 2.0 ng/mL (pediatric controls) [22] 1.6% Low, except in patients with 21-hydroxylase deficiency
• Up to 1,005 ng/mL (21-hydroxylase deficiency) [22]
Formestane Up to 14 ng/mL in breast cancer patients [29] 1.2% Low
Androstenedione • Up to 0.86 ng/mL before onset of puberty [30] 0.9% Low
• Up to 3.2 ng/mL in 21-hydroxylase deficiency [30]
Prednisone Up to 57 ng/mL in pediatric transplant patients receiving prednisolone [21] 0.3% Low