Testosterone Cypionate Seasonal Use Considerations

Does natural testosterone change with the seasons?

Yes, in at least one large cross-sectional study. In 1,548 men living in northern Norway, total testosterone had a bimodal pattern: a small peak in February, a nadir in June, and a larger peak in October and November. Free testosterone peaked in December and was lowest in August. The difference between the lowest and highest monthly mean free testosterone was 31% [2].

That study measured testosterone levels in men in northern Norway, not levels during testosterone cypionate treatment [2].

Does that rhythm carry over to testosterone cypionate?

It is not known whether the seasonal pattern also occurs during testosterone cypionate treatment. Injected testosterone suppresses the body's own luteinizing hormone [1]. The label gives 50 to 400 mg every 2 to 4 weeks, adjusted according to the patient's response and adverse reactions, and says the half-life is approximately 8 days after intramuscular injection [1].

Is summer heat a reason to change the dose?

The label's stated basis for dose adjustment is response and adverse reactions [1]. It is not known whether summer heat changes testosterone cypionate absorption, peak levels, or trough levels.

Does vitamin D change testosterone levels?

In a year-long randomized trial of 200 people, testosterone results were analyzed from the 54 men who completed the study [5]. The 31 men assigned 3,332 IU vitamin D daily had total testosterone rise from 10.7 to 13.4 nmol/L, while the placebo group had no significant change [5]. The men were healthy and overweight, taking part in a weight-reduction program [5]. The authors said further randomized trials are needed to confirm the finding [5].

Does testosterone cypionate affect hematocrit?

Testosterone therapy raises hematocrit [3]. A network meta-analysis of 29 placebo-controlled trials and 3,393 men found that intramuscular testosterone enanthate/cypionate raised mean hematocrit by 4.0% versus placebo [3]. A retrospective review of 178 men found erythrocytosis, defined as hematocrit above 50%, in 66.7% of men on injectable testosterone compared with 12.8% on gels; the injection group was younger and had higher baseline hematocrit, and the study was not randomized [6]. The Depo-Testosterone label says to check hemoglobin and hematocrit periodically during long-term use [1]. Whether the season changes hematocrit during treatment is not known.

Is a winter mood change a reason to change the dose?

The Depo-Testosterone label lists depression among its nervous-system adverse reactions [1]. No source here tests seasonal mood changes as a basis for changing the testosterone cypionate dose.