INTRODUCTION: Cross-sectional and longitudinal cohort studies examining the relationship between serum testosterone concentration and depression in men have produced mixed results. There has not, however, been any prior attempt to systematically interrogate the data. Clarification of the relationship has clinical importance because depression may be under-diagnosed in men.
INCLUSION CRITERIA: This review will consider studies involving community-dwelling men who are not receiving testosterone replacement therapy. The exposure of interest reviewed will include endogenous testosterone concentration measured through validated assays. Studies measuring total and testosterone fraction concentration will be included. This review will include studies with depression or incident depression outcomes as defined by either clinical diagnosis of depression or validated self-administered questionnaire assessing depression symptomatology.
METHODS: This review will follow the JBI approach for systematic reviews of etiology and risk. The following sources will be searched: PubMed, PsycINFO, Embase, the Cochrane Central Register of Controlled Trials, Australian New Zealand Clinical Trials Registry and the ISRCTN Registry. Analytical observational studies including prospective and retrospective cohort studies, case control studies and analytical cross-sectional studies published in English or other languages with English translation will be considered. Retrieval of full-text studies, assessment of methodological quality and data extraction will be performed independently by two reviewers. Data will be pooled in statistical meta-analysis, where possible.
SYSTEMATIC REVIEW REGISTRATION NUMBER: PROSPERO CRD42018108273.
METHODS: Chinese and Malay men (n = 382) aged 20 years or above residing in the Klang Valley, Malaysia were recruited. Their fasting blood was collected for serum testosterone, sex hormone-binding globulin (SHBG) and 25-hydroxyvitamin D (25(OH)D) assays. Relationship between 25(OH)D and testosterone levels was analyzed using multiple regression analysis. Testosterone and SHBG levels among subjects with different vitamin D status were compared using univariate analysis. Confounders such as age, ethnicity and body mass index (BMI) were adjusted.
RESULTS: 25(OH)D was significantly and positively associated with total testosterone and SHBG levels before and after adjustment for age and ethnicity (p 0.05).
CONCLUSION: 25(OH)D is significantly associated with total testosterone and SHBG in Malaysian men but this association is BMI-dependent.
AIM OF THE STUDY: Since kratom is reported to deform sperm morphology and reduce sperm motility, we aimed to clinically investigate the testosterone levels following long-term kratom tea/juice use in regular kratom users.
METHODS: A total of 19 regular kratom users were recruited for this cross-sectional study. A full-blood test was conducted including determination of testosterone level, follicle stimulating hormone (FSH) and luteinizing hormone (LH) profile, as well as hematological and biochemical parameters of participants.
RESULTS: We found long-term kratom tea/juice consumption with a daily mitragynine dose of 76.23-94.15 mg did not impair testosterone levels, or gonadotrophins, hematological and biochemical parameters in regular kratom users.
CONCLUSION: Regular kratom tea/juice consumption over prolonged periods (>2 years) was not associated with testosterone impairing effects in humans.