An Unintended Benefit of Anabolic Steroid Use: Therapy of Hemophilia B Leiden.

Abstract Abstract 3661 Introduction: In Hemophilia B Leiden, administration of testosterone and anabolic steroids in pre-pubertal boys can raise endogenous Factor IX (FIX) to levels sufficient to prevent most hemorrhages. It is unknown whether this androgen responsiveness may occur even in the post-pubertal male. We present a case that unintentionally demonstrated this phenomenon. Case: A 29-year-old man with mild Hemophilia B (baseline Factor IX [FIX] level 12%) presented to the emergency department with acute left quadriceps swelling. He received 1,800 units (18 U/kg) of human factor IX concentrate and the following day FIX level was 80%. One day later, he was seen with persistent pain and swelling despite adequate factor replacement. The patient disclosed that he had been using intramuscular injections of the anabolic steroid stanozolol. On suspicion that the thigh swelling may represent abscess rather than hematoma, blood cultures were drawn and grew Staphylococcus aureus. He received appropriate antibacterial therapy and 1.5 liters of purulent material was drained from the thigh. Intriguingly, FIX level one month after discharge was still 61%. One year later, his FIX level had stabilized at 36%. Given the persistently elevated FIX level compared to baseline, the FIX gene was sequenced. Genotyping revealed a G to A transition at nucleotide -6 within the promoter region of the FIX gene. Mutations within nucleotides -34 to +19 of the 5′ region (Leiden-specific region) of the FIX promoter are associated with the Hemophilia B Leiden phenotype. This rare form of Hemophilia B improves following puberty. There is an androgen-response element (ARE) located at the -26 position of the FIX promoter, within the Leiden-specific region. The mechanism of recovery is not fully understood, but it is postulated that in the presence of androgen binding to the ARE, a normal FIX gene can be transcribed, thus overcoming the mutation causing the hemophilia phenotype prior to puberty. It has been shown that mutations involving the ARE do not resolve after puberty, which suggests an androgen responsive mechanism to the increase in FIX. Conclusion: This case raises the possibility of androgen-responsive increases in FIX that persist after puberty. We propose that a further rise in the FIX levels occurred as a result of exogenous exposure to pharmacologic concentrations of androgens in the post-pubertal period. This deliberate use of exogenous androgens carried the unintended benefit of abolishing the Hemophilia B phenotype. Disclosures: No relevant conflicts of interest to declare.

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