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Table 5 Testosterone 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
Testosterone (endogenous compound) • 0 – 10 ng/mL (males) [49] 100% High (assay target)
• 0 – 0.5 ng/mL (females) [49]
Methyltestosterone Up to 40 ng/mL following single dose [50] 12.2% High, especially if measured during peak concentration
Boldenone Up to 1.1 ng/mL in horses following dosing [51] 7.2% Likely low, although there is lack of human pharmacokinetic data
19-Norclostebol Unknown 6.7% Unknown, no human pharmacokinetic data available
Norethindrone Up to 20 ng/mL while on medication [3941] 6.7% Possible significant contribution in women taking norethindrone, especially if specimen drawn near peak of norethindrone concentration
11β-Hydroxytestosterone Unknown 5.5% Unknown, no human pharmacokinetic data available
Methandrostenolone Unknown 5.4% Unknown, no human pharmacokinetic data available
Normethandrolone Unknown 5.4% Unknown, no human pharmacokinetic data available
Nandrolone Up to 5.16 ng/mL [47] 2.1% Low
Androstenedione • Up to 0.86 ng/mL before onset of puberty [30] 1.2% Low
  • Up to 3.2 ng/mL in 21-hydroxylase deficiency [30]