ESPE Abstracts

Background: Klinefelter syndrome (XXY) is characterised by sex hormone aneuploidy. It is one the most common causes of primary hypogonadism, impaired spermatogenesis and testosterone deficiency. It affects around 1 in 500 phenotypic males. Approximately 25% of the patients are diagnosed in childhood. The hallmark of the condition is the small volume of the testicles and azoospermia. Most adolescent progress through puberty at the expense of elevated gonadotrophins.

Aim: To review the investigations, management and treatment all adolescents with XXY who were seen within a tertiary UK paediatric endocrine service.

Methods: We retrospectively reviewed the data for all adolescents with XXY born after 2000. All boys over 11 years of age were included. The pubertal stage was documented and whether gynaecomastia was present. The levels of LH, FSH and testosterone were recorded and finally whether additional treatment with testosterone was provided.

Results: Seventeen adolescents of pubertal age were identified with an age range of 11.7 to 17.1 years. The majority of the boys (13) were Tanner stage 3 to 5. Two patients did not have pubertal stage recorded and 2 were Tanner stage 1 or 2. Seven had gynaecomastia; this was the presenting symptom in 4. The range of testosterone levels was 4 to 20.1 nmol/L (normal range 8–30). Only one had a testosterone level in the upper half of the normal adult range (>19 nmol/L). In the group of adolescents with Tanner stage 3+, median LH was 18.2, FSH 54.6 and testosterone 10.65 nmol/L. This was at a median age of 15.2 years. The gonadotrophins were not elevated in one boy with Tanner stage 2, one other prepubertal boy did not have blood tests checked as yet. Three out of the seventeen adolescents required testosterone treatment with a median start age of 15.9 years. Blood results showed a median LH 15.9, FSH of 68.2 nmol/L and testosterone of 9.8 nmol/L. Four of the adolescents have not had blood tests.

Conclusions: Hypogonadism in XXY is common. Three out of thirteen boys who had blood tests done required testosterone treatment. Our group rarely had a testosterone level above the mid-adult range. These teenagers should continue to have on going surveillance to ensure adequate testosterone referrals. A referral to adult endocrinology and fertility teams should also be considered so that they are well versed in future management options.