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PLoS One. 2019 Sep 11;14(9):e0221992. doi: 10.1371/journal.pone.0221992. eCollection 2019.

Male sexual dysfunction in obesity: The role of sex hormones and small fibre neuropathy.

Author information

Department of Medicine, Manchester University NHS Foundation Trust, Manchester, United Kingdom.
Cardiovascular Research Group, The University of Manchester, Manchester, United Kingdom.
Department of Biochemistry, Wythenshawe Hospital, Manchester University NHS Foundation Trust, Manchester, United Kingdom.
Department of Diabetes & Endocrinology, Salford Royal NHS Foundation Trust, Salford, United Kingdom.
Department of Surgery, Salford Royal NHS Foundation Trust, Salford, United Kingdom.
Department of Endocrinology, Our Lady of Lourdes Hospital, RCSI Hospital Group, Drogheda, Ireland.
Department of Medicine, Weill Cornell Medicine-Qatar, Doha, Qatar.



Multiple factors contribute to sexual dysfunction in men with obesity. Sex hormone levels are commonly abnormal in men with obesity and this abnormality is often the focus of management in clinical practice. The role of small fibre neuropathy in obesity-related sexual dysfunction is not well established.


We aimed to investigate the relationship between sexual function, sex hormone levels and small nerve fibre morphology in men with severe obesity.


A prospective study of 29 men with severe obesity was undertaken. Sexual function was assessed using the European Male Ageing Study Sexual Function Questionnaire. Small nerve fibre morphology was quantified using corneal confocal microscopy. Sex hormone levels were measured by mass spectrophotometry.


Erectile dysfunction was present in 72% of the cohort with a higher prevalence of diabetes among the symptomatic group (88% vs 38%, p = 0.006). Corneal nerve fibre length (CNFL) and corneal nerve fibre density (CNFD) were both significantly lower in participants with erectile dysfunction compared to those without (p = 0.039 and p = 0.048 respectively). The erectile function score correlated with CNFL (r = -0.418, p = 0.034) and CNFD (r = -0.411, p = 0.037). Total testosterone and calculated free testosterone levels did not differ significantly between men with or without erectile dysfunction (median 8.8 nmol/L vs 9.0 nmol/L, p = 0.914; and median 176 pmol/L vs 179 pmol/L, p = 0.351 respectively), infrequent sexual thoughts (median 8.1 nmol/L vs 9.2 nmol/L, p = 0.650; and median 184 pmol/L, vs 176 pmol/L, p = 0.619 respectively) and decreased morning erections (median 9.0 nmol/L vs 8.8 nmol/L, p = 0.655; and median 170 pmol/L vs 193 pmol/L, p = 0.278 respectively).


Sexual dysfunction is highly prevalent in men with severe obesity. We found an association between small fibre neuropathy with erectile dysfunction with presence of diabetes a likely a significant contributing factor. We found no associations between testosterone levels with sexual symptoms (including frequency of sexual thoughts). The influence of small nerve fibre neuropathy on response to therapeutic interventions and whether interventions that improve small fibre neuropathy can improve erectile function in this population merits further study.

Conflict of interest statement

This study was partially funded by a research donation from AMGEN. This does not alter our adherence to PLOS ONE policies on sharing data and materials. There are no patents, products in development or marketed products associated with this research to declare.

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