Borderline‐low testosterone levels are associated with lower left ventricular wall thickness in firefighters: An exploratory analysis

Abstract

Background Low endogenous testosterone has been associated with increased cardiovascular risk in men. Objectives To determine the prevalence of low serum testosterone level (TT) in a cohort of male US career firefighters and to examine its relation with left ventricular wall thickness (LVWT). Materials and Methods We conducted a cross‐sectional study among 341 career firefighters, (age: 37.5 ± 10.3 years; BMI: 28.9 ± 4.5 kg/m2), who underwent an occupational medical screening examination. TT quartiles were determined, and LVWT distribution among them was plotted. Then, TT values were categorized as low (<264 ng/dL), borderline (264‐399 ng/dL), reference range (400‐916 ng/dL), and high (>916 ng/dL). To further investigate the association of mildly decreased TT on LVWT, we divided the borderline group into borderline‐low (264‐319 ng/dL) and borderline‐high (320‐399 ng/dL) ranges. LVWT values were classified as low LVWT when <0.6 cm. A multivariate model was used to compare LVWT, age, BMI, systolic blood pressure (SBP), and HbA1c among groups by TT values. Results The prevalence of low TT was 10.6% and of borderline was 26.4%, while 58.7% had levels in the reference range. The low‐TT group was older and had higher BMI and SBP as compared to the reference group (P < .01). LVWT values were different among groups (P = .04) and significantly lower in firefighters with borderline‐low TT as compared to the reference group (P < .05). This finding also occurred within obese firefighters (P = .03). The borderline‐low group had a higher adjusted risk for a low LVWT as compared to the reference group [OR: 4.11 (95% CI: 1.79‐9.43)]. Discussion Our findings highlight the possible relationship between a mild reduction in testosterone levels (borderline) and lower LVWT. Conclusions A high prevalence of subnormal TT levels (low and borderline: 37%) was observed in this relatively homogeneous cohort of career firefighters. Mildly decreased TT levels and lower LVWT might represent a preclinical condition and a window of opportunity for cardiovascular preventive interventions in firefighters.

Low testosterone and cardiometabolic risks in a real-world study of US male firefighters

“…These findings are of particular concern among firefighters due to the acute effects of firefighting on vascular function 2 , 20 and the high prevalence of left ventricular hypertrophy or cardiomegaly in autopsies of firefighters who died due to cardiac conditions 47 . Of note, we have recently shown that firefighters with borderline-low TT levels (between 264 and 320 ng/dL) have a fourfold higher risk of having a lower left ventricular wall thickness, independently of age, BMI, and HbA1 16 . Whether the available cardiovascular findings correlate with fatty liver and/or an unfavorable overall cardiometabolic profile related to low testosterone levels is still hypothetical, thus highlighting the need for additional studies.…”

“…The present study is a novel research arm of a recently published study from our group. The initial study population included all male firefighters (n = 341) in a fire department in Florida who were cleared for firefighting duty and had a normal ejection fraction (> 55%), as previously described 16 . For the current study, 23 subjects were excluded due to the absence of two or more results in the studied variables (missing data), and 11 due to elevated testosterone levels at the time of the occupational health evaluation (> 916 ng/dL).…”

“…A direct or reverse causality is yet to be clarified 12 due to complex interactions between TT and CV health, especially in firefighters. Testosterone deficiency (TD) and CV diseases share common risk factors, such as obesity and metabolic syndrome 13,14 , which are highly prevalent among firefighters [15][16][17][18] .Clinically, low testosterone is most commonly associated with increased visceral obesity, loss of muscle mass, fatigue, loss of bone strength, altered mood and low sex drive 8 . In regards to firefighters, the screening for testosterone deficiency is particularly relevant because: (a) firefighting independently induces a pro-coagulatory state 4,19,20 ; (b) firefighting can impair vascular function which may be further potentiated by testosterone imbalances; (c) firefighters commonly exhibit multiple risk factors that are associated with low testosterone levels, including obesity, metabolic dysfunction and sleep disturbance [21][22][23] .…”

“…A direct or reverse causality is yet to be clarified 12 due to complex interactions between TT and CV health, especially in firefighters. Testosterone deficiency (TD) and CV diseases share common risk factors, such as obesity and metabolic syndrome 13,14 , which are highly prevalent among firefighters [15][16][17][18] .…”

Testosterone and occupational burnout in professional male firefighters

“…Studies on testosterone levels in firefighters are sporadic. There is only one report of the association of borderline-low testosterone with low left ventricular thickness from the annual screening data [ 10 ]. Other authors studied the estrogenic and antiestrogenic activity of the deposits on firefighters gear [ 11 ].…”