Table 1 Cortisol immunoassay 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 [26–28]

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