ESPE Abstracts

Background: Delayed puberty is defined as the absence of physical signs of puberty 2 to 2.5 standard deviations greater than the mean and affects 2% of the adolescent population. We present a male patient aged 16, presenting with delayed puberty. On direct questioning the patient revealed he had been taking regular Gamma-Aminobutyric Acid (GABA). These supplements appeared to suppress the hypothalamic-pituitary-gonadal (HPG) axis.

Case Presentation: A 16-year-old male patient presented to primary care with concerns about a lack of pubertal development. No significant past medical history was noted. No family history of delayed puberty was elicited. The patient revealed he had been taking over the counter GABA capsules to help alleviate stress and improve sleep.

On examination the patient had no secondary sexual characteristics. His pubic hair was sparse, testicular volume was 5ml and the external genitalia were consistent with Tanner stage 2. His height was within two centile spaces of the mid-parental centile and BMI appropriate for age.

Initial investigations showed; Serum testosterone (7.7 nmol/L [10-28 nmol/L]), Luteinising hormone (LH) 2.0 IU/L [2-9 IU/L] and Follicle Stimulating Hormone (FSH) 2.4 IU/L [1-12 IU/L]. A subsequent Gonadotrophin Releasing Hormone (GnRH) test confirmed a suppressed HPG axis [basal LH 1.9 IU/L, with stimulated peak of 2.8 IU/L, basal FSH 1.1 IU/L, with stimulated peak of 1.6 IU/L].

Following cessation of the GABA capsules there was immediate recovery of the HPG axis. A repeat GnRH test, performed two weeks following cessation of the medication showed an LH dominant response [Basal LH 5.6 IU/L, with a stimulated peak of 16.1, basal FSH 5.3, with stimulated peak of 7.5].

Following the discontinuation of GABA capsules, the patient was monitored over a period of six months. Consonant puberty has progressed and the patient is now Tanner stage V. No further concerns were noted. The patient was subsequently discharged from clinic.

Conclusions: In recent years there has been a significant rise in the sale of oral GABA capsules as food supplements, manufacturers report that the supplements can alleviate stress, reduce anxiety and help improve sleep disorders. Despite these claims there are few good quality studies which have clearly demonstrated that GABA supplementation can improve such symptoms. To our knowledge this is the first reported case of GABA supplements causing suppression of the HPG axis and subsequent pubertal delay.