Why Topical Testosterone Gel Rarely Raises Hemoglobin and Hematocrit

Topical testosterone gel has become a popular option for men who need testosterone replacement but want to avoid the hematocrit spikes often seen with injections. While any androgen can stimulate red blood cell production, the way gel delivers testosterone to the body creates a much gentler signal to the bone marrow. At True North Metabolic TRT Clinic in Kitchener-Waterloo, this is one of the key reasons we often favor transdermal therapy in patients who already run “thick” on their labs or who have cardiovascular risk factors.

The Core Mechanism: Testosterone and Red Blood Cell Production

Testosterone increases hemoglobin and hematocrit by boosting erythropoietin (EPO) production in the kidneys and lowering hepcidin, which liberates iron for red blood cell synthesis. This mechanism is the same whether testosterone is given by injection, gel, or pellets. The difference is not what testosterone does, but how much and how fast it hits the system. Topical gel provides a slow, steady input rather than sharp peaks, so the EPO and marrow stimulation are typically modest and more physiologic.

Flatter Pharmacokinetics Mean Less Erythrocytosis

When gel is applied once or twice daily, it produces a relatively stable serum testosterone level throughout the day. There may be mild fluctuations around application time, but the amplitude of those changes is small compared to injections. With no large supraphysiologic spike, the marrow does not receive the same “urgent” signal to ramp up red blood cell production. Over time, that flatter pharmacokinetic profile translates into a lower incidence and lower magnitude of hematocrit elevations compared with injectable regimens.

Why Gels and Creams Mimic Natural Physiology Better

Endogenous testosterone production in healthy men follows a circadian rhythm: higher in the morning, gently declining through the day, but without massive swings. Transdermal preparations come closer to imitating that natural pattern. The skin acts as a slow-release reservoir, allowing continuous absorption. Instead of the body seeing a big pulse of testosterone followed by a long tail, it sees a background level that is nudged into the mid-normal range. This physiologic replacement style is less likely to push hemoglobin and hematocrit into the risk zone.

The Role of Dose Titration and Skin Absorption

Another advantage of gel is the ability to make small dose adjustments. You can fine-tune the daily amount based on symptoms and labs, rather than making large jumps in weekly milligrams. Absorption through the skin is somewhat self-limiting as well; once the application area is saturated, additional gel is not absorbed linearly. At True North Metabolic TRT Clinic in Kitchener-Waterloo, dose adjustments are made in small, deliberate steps, with follow-up bloodwork to ensure testosterone is optimized without driving hematocrit upward.

Who Still Gets Hematocrit Increases on Gel?

Topical testosterone is not completely immune to erythrocytosis. Men with significant underlying risk factors can still see hemoglobin and hematocrit climb, even on modest gel doses. Obstructive sleep apnea, smoking, chronic lung disease, high altitude, and intrinsic bone marrow sensitivity all amplify the erythropoietic response. In those cases, any rise in testosterone may tip the balance. The difference is that with gel, the increases tend to be slower and less dramatic, allowing more time for monitoring and intervention before levels reach a dangerous threshold.

Clinical Implications for Safety and Monitoring

Because topical gel produces smoother serum levels, patients often report fewer swings in mood, energy, and libido, and their blood counts typically behave more predictably. That said, regular monitoring of complete blood counts remains essential. If hematocrit begins to drift upward, steps such as reducing the gel dose, addressing sleep apnea, encouraging smoking cessation, or adjusting application timing can often stabilize it without abandoning therapy. Only rarely is therapeutic phlebotomy needed in patients maintained on a well-titrated gel regimen.

Why Topical TRT Is Often Preferred in Higher-Risk Patients

For men with prior venous thromboembolism, established cardiovascular disease, or baseline high hematocrit, the route of testosterone delivery matters. In these situations, transdermal therapy offers a way to replace testosterone while minimizing sharp hormonal peaks and the associated erythropoietic drive. At True North Metabolic TRT Clinic in Kitchener-Waterloo, topical gel is frequently the first-line option in patients where hematologic safety is a priority, combining symptom relief with a lower likelihood of clinically significant rises in hemoglobin and hematocrit.

True North Metabolic Men's Health Clinic services patients in Kitchener-Waterloo , Cambridge, Ontario and Guelph, Ontario as well as surrounding regions in Ontario.