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Endocrine Abstracts (2019) 65 P371 | DOI: 10.1530/endoabs.65.P371

University College London Hospital, London, UK


Background: Klinefelter syndrome (KS), karyotype 47XXY, affects 1 in 650 males. Subjects develop primary gonadal failure requiring life-long testosterone replacement. Many different testosterone formulations are available and long-term monitoring is necessary to avoid secondary polycythaemia.

Objective: To investigate the effect of testosterone formulations used in KS subjects and estimate frequency of association with secondary polycythaemia.

Method: A single institution retrospective review of the hospital database was undertaken to identify KS subjects. Collated data included formulation of testosterone replacement and evidence of secondary polycythaemia – defined as either a haemoglobin > 170 g/l or a haematocrit > 0.54 l/l.

Results: 83 subjects with KS were identified. 72 subjects (87%) took some form of testosterone or hCG. Of these 72 subjects, 34 (47%) took testosterone undecanoate (Nebido), 7 (10%) took testosterone esters (Sustanon), 23 (32%) took topical testosterone gel (Testogel or Tostran) and 8 (11%) took Pregnyl/Gonasi. 10 of 72 (14%) subjects had evidence of polycythaemia at some point during follow-up. In 2 subjects, both the haemoglobin and haematocrit were raised; only the haemoglobin was raised in the remaining 8 subjects. 7 subjects took testosterone undecanoate (intervals: 13 weekly(1); 12 weekly(4); 10 weekly(1) and 750 mg 20 weekly(1)) and 3 took daily testosterone gel subjects (Testogel(2) and Tostran(1)) – 20.5% of subjects taking testosterone undecanoate and 13% of subjects taking testosterone gel developed polycythaemia. 2 subjects (one taking Nebido, the other Testogel) required venesection as treatment for polycythaemia, with others only requiring dose alteration.

Conclusion: A significant minority of KS subjected developed polycythaemia whilst on testosterone therapy. Testosterone undecanoate appears to be associated with the highest risk despite published data reporting a relatively low risk with this preparation. In the KS cohort, avoidance of polycythaemia is important given the increasing risk of venous thromboembolic disease with age.

Volume 65

Society for Endocrinology BES 2019

Brighton, United Kingdom
11 Nov 2019 - 13 Nov 2019

Society for Endocrinology 

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