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Endocrine Abstracts (2016) 45 OC6.3 | DOI: 10.1530/endoabs.45.OC6.3

1Royal Alexandra Children’s Hospital, Brighton, UK; 2Kings College Hospital, London, UK.


Introduction: In total of 5α-reductase 2 is vital in sexual development of male foetus; its deficiency causes impaired virilisation due to defective conversion of testosterone to dihydrotestosterone and is an important cause of Disorders of Sexual Development (DSD). We report 3 cases of severe primary acquired auto-immune hypothyroidism, which show a similar picture of 5α-reductase deficiency (5ARD) on urine steroid profile (USP) and reversible following adequate thyroxine replacement therapy.

Case Reports: Case 1: 13 year old boy with poor growth was finally diagnosed as primary hypothyroidism (TSH >100 mu/l; FT4 4 pmol/l). USP performed due to small penile size and lack of pubertal development showed 5ARD with hypothyroidism reversing when euthyroid, prompting USP review in subsequent cases.

Case 2: 11 year old girl with short stature was confirmed as auto-immune hypothyroidism (TSH >100 mu/l; FT4 0.9 pmol/l). USP showed 5ARD during untreated stage, which reversed completely on thyroxine replacement therapy.

Case 3: 11 year old boy with poor growth was diagnosed as profound hypothyroidism (TSH >100 mu/l; FT4 undetectable). USP showed 5ARD; awaiting repeat USP following treatment.

Results: In total of 3 patients with severe hypothyroidism showed 5ARD and normalisation of 5α reductase steroid markers with thyroxine replacement. The ratios of 5α/5β-reduced tetrahydrocortisol were 0.02, 0.08 and 0.10 in Case 1, 2 and 3 respectively (Normal: Mean 1.04; SD 0.89). Ratios for Case 2 after 2 & 4 months of treatment were 0.36 & 1.69. Ratios for the 5α/5β-reduced androstenedione metabolites were less abnormal, indicating a specific impairment of the 5α-reductase 2 isoform in hypothyroidism.

Conclusion: In total of 5α reductase-2 deficiency is a rare disorder leading to incomplete male genitalia development in patients with 46XY DSD. Untreated or undiagnosed hypothyroidism is a potential cause of reversible 5α reductase-2 deficiency. Altered steroid metabolism in hypothyroidism, if undetected may lead to erroneous results and interpretation of USP; thus excluding hypothyroidism in diagnostic work ups for DSD, especially patients with late presentations is extremely important.

Novel insight: We have demonstrated altered steroid metabolism in hypothyroidism – a completely reversible picture of 5ARD with adequate thyroxine replacement therapy; if undetected, may lead to errors in interpreting USP results whilst investigating DSD.

Volume 45

44th Meeting of the British Society for Paediatric Endocrinology and Diabetes

British Society for Paediatric Endocrinology and Diabetes 

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