Does Testosterone Raise Vitamin B12 Levels?
No, testosterone replacement therapy does not raise vitamin B12 levels—in fact, the relationship appears to work in the opposite direction, where higher B12 levels may be associated with higher testosterone concentrations.
The Evidence Shows Reverse Causation
The available evidence does not support that testosterone therapy increases B12 levels. Instead, research demonstrates the opposite relationship:
Higher serum vitamin B12 concentrations are associated with higher testosterone levels in men with infertility, showing a positive correlation (ρ = 0.19, P = 0.001) between B12 and total testosterone 1.
Men in the highest tertile of serum B12 had significantly reduced odds of testosterone deficiency (adjusted OR = 0.44; 95% CI: 0.22,0.87, P = 0.02) compared to those in the lowest tertile, suggesting B12 may influence testosterone production rather than the reverse 1.
What Testosterone Therapy Actually Affects
Comprehensive guidelines on testosterone replacement therapy document its effects on multiple physiologic parameters, but vitamin B12 is notably absent from any monitoring recommendations or known effects 2.
Testosterone therapy's well-documented effects include:
Erythrocytosis: Hemoglobin and hematocrit increase by 15-20%, with 43.8% of patients on intramuscular injections developing elevated hematocrit (>52%) 2.
Neutral lipid effects: Total cholesterol was reduced in 5 studies, increased in 2, and unchanged in 12 studies; LDL remained unchanged or decreased in 14 of 15 studies 2, 3.
Prostate effects: PSA may increase by approximately 0.30-0.43 ng/mL, and prostate volume increases mainly during the first six months 2.
Clinical Implications
If you are considering whether testosterone therapy will correct a B12 deficiency, the answer is definitively no. B12 deficiencies must be addressed independently through:
- Direct B12 supplementation (oral or intramuscular depending on absorption capacity)
- Evaluation and treatment of underlying causes (pernicious anemia, malabsorption, dietary insufficiency)
Conversely, in men with both low testosterone and low B12, correcting the B12 deficiency may potentially improve testosterone levels and androgenic profiles, particularly in the context of infertility 1.
Common Pitfall to Avoid
Do not assume that testosterone therapy will correct other nutritional or hormonal deficiencies. The high prevalence of concurrent B12 and testosterone deficiencies (76% in one chronic pain cohort) 4 means both should be screened and treated independently when clinically indicated.