Vitamin D Correlation with Testosterone Concentration in US Army Special Operations Personnel

Abstract

Vitamin D has been positively correlated with testosterone in older men, but these hormonal relationships have not been examined in younger, active military personnel. Therefore, the purpose of this study was to identify significant correlations between vitamin D and testosterone concentrations in male Special Operations Soldiers. This retrospective analysis examined unique cases of serum vitamin D assessments ordered at Womack Army Medical Center, Fort Bragg, NC, from January 2012 – September 2013. Inclusion criteria were male Special Operations soldiers who had a total testosterone assessment within 21 days of vitamin D assessment, yielding 312 service member records. Mean serum vitamin D concentrations were 29.9±9.6 ng/ml (range 10-63), with 52% of subjects in the deficient range of <30 ng/ml according to the Army Medical Department guidelines. In vitamin D deficient subjects, serum vitamin D concentrations were a significant positive predictor of total testosterone when controlling for age and body mass index. These data indicate that deficient vitamin D concentrations may inhibit testosterone production and potentially limit human performance. Operational stress of military training has been shown to suppress testosterone concentrations in healthy men, causing muscle catabolism and fatigue, symptoms also characteristic of vitamin D deficiency. Given that more than half of male soldiers had insufficient vitamin D status in a southern latitude, measuring vitamin D concentrations in collaboration with testosterone assessments may be warranted. No funding was used to support this work.

Full text

733.5 ABSTRACT
Vitamin D has been positively correlated with testosterone in older men,
but these hormonal relationships have not been examined in younger,
active military personnel. Therefore, the purpose of this study was to
identify significant correlations between vitamin D and testosterone
concentrations in male Special Operations Soldiers. This retrospective
analysis examined unique cases of serum vitamin D assessments
ordered at Womack Army Medical Center, Fort Bragg, NC, from
January 2012 – September 2013. Inclusion criteria were male Special
Operations soldiers who had a total testosterone assessment within 21
days of vitamin D assessment, yielding 312 service member records.
Mean serum vitamin D concentrations were 29.9 ± 9.6 ng/ml (range
10-63), with 52% of subjects in the deficient range of <30 ng/ml
according to the Army Medical Department guidelines. In vitamin D
deficient subjects, serum vitamin D concentrations were a significant
positive predictor of total testosterone when controlling for age and
body mass index. These data indicate that deficient vitamin D
concentrations may inhibit testosterone production and potentially limit
human performance. Operational stress of military training has been
shown to suppress testosterone concentrations in healthy men, causing
muscle catabolism and fatigue, symptoms also characteristic of vitamin
D deficiency. Given that more than half of male soldiers had insufficient
vitamin D status in a southern latitude, measuring vitamin D
concentrations in collaboration with testosterone assessments may be
warranted. No funding was used to support this work
Vitamin D Correlation with Testosterone Concentration in US Army
Special Operations Personnel
Laurel M Wentz1, Cristóbal S Berry-Cabán2, Jerad D Eldred2, Qiang Wu1
1Nutrition Science, East Carolina University, Greenville, NC, 2Department of Clinical Investigation, Womack Army Medical Center, Fort Bragg, NC
PURPOSE
The purpose of this study was to identify significant
correlations between vitamin D and testosterone
concentrations in male Special Operations Personnel.
METHODS
! This analysis examined unique cases of serum vitamin D
assessments ordered at Womack Army Medical Center from
January 2012 – September 2013
! 18,595 vitamin D assessments were ordered during this
time period, of which 312 met the inclusion criteria for this
analysis:
" Male soldiers
" Special Operations Unit
" Testosterone assessment within 21 days of vitamin D
assessment
! Data were analyzed for descriptive statistics. General linear
models were used to test the effect of vitamin D level on total
testosterone using age and BMI as covariates
! The WAMC Institutional Review Board approved this study
ACKNOWLEDGEMENTS
We appreciate the assistance of John Rehder from WAMC Information
Management Division and 3rd SFG (A) Medical Operations
RESULTS
CONCLUSIONS
! These data show a high prevalence of vitamin D deficiency
in male Special Operations Personnel assessed in the
southeast region of the United States
! At low 25(OH)D concentrations, a linear relationship with
testosterone concentrations emerged that indicates
vitamin D deficiency may limit testosterone synthesis and
potentially limit human performance
! Serum 25(OH)D was a significant positive predictor of
testosterone when controlling for age and BMI in vitamin D
deficient/insufficient service members
! To our knowledge, this is the first report linking vitamin D
to testosterone in military personnel. Previous research
has correlated vitamin D with testosterone in older men
and shown that vitamin D supplementation increases
testosterone concentrations in vitamin D deficient men1
! Symptoms of vitamin D deficiency are consistent with
hypothalamo-pituitary dysfunction, such as fatigue,
depression, cognitive deficiencies, and loss of
neuromuscular function2
Since both vitamin D deficiency and hypothalamo-
pituitary dysfunction plague service members, future
research should prospectively assess vitamin D
status in comprehensive treatment plans for
endocrine disorders
REFERENCES
1. Pilz S, Frisch S, Koertke H, Kuhn J, Dreier J, Obermayer-Pietsch B, Wehr E,
Zitterman A. Effect of vitamin D supplementation on testosterone levels in men.
Horm Metab Res. 2011;43(3):223-225.
2. Wilkinson CW, Pagulayan KF, Petrie EC, Mayer CL, Colasurdo EA, Shofer JB,
Hart KL, Hoff D, Tarabochia MA, Peskind ER. High prevalence of chronic pituitary
and target-organ hormone abnormalities after blast-related mild traumatic brain
injury. Front Neurol. 2012;3:11.
! Mean total testosterone levels were 437.6 ± 176.9 ng/dl
! Mean age was 39.6 ± 7.4 years
! Race and ethnicity identifiers were too limited to include
in analysis
! 25(OH)D concentrations were not significantly
correlated with testosterone concentrations in all men
(r = 0.096; P = 0.089)
In vitamin D deficient and insufficient men,
25(OH)D concentrations were significantly,
positively correlated with testosterone
concentrations (r = 0.243; P = 0.002)
The views expressed are those of the authors and do not reflect the official policy or position of the Department of Defense or the U.S. Government.
! Mean vitamin D levels were 29.9 ± 9.6 (10-63) ng/ml
" 15.1% deficient (n = 47)
" 36.8% insufficient (n = 115)
" 48.1% sufficient (n = 150)
According the laboratory ranges in the Army Medical
Department Guidelines