IS YOUR HAEMATOCRIT TOO HIGH?
Mechanisms of Increased Haematocrit Due to Testosterone.
Stimulation of Erythropoiesis:
Testosterone stimulates the production of erythropoietin, a hormone produced by the kidneys that promotes the formation of red blood cells in the bone marrow. Increased erythropoietin levels accelerate red blood cell production, raising haematocrit levels.
Testosterone directly acts on the bone marrow to increase the production of red blood cells. It enhances the proliferation and differentiation of erythroid progenitor cells (the cells that develop into red blood cells). This increased activity in the bone marrow leads to a higher red blood cell count and, consequently, an elevated haematocrit.
Effect on Hormones and Iron Metabolism:
Testosterone decreases the levels of hepcidin, a hormone that regulates iron homeostasis in the body. Lower hepcidin levels result in increased iron absorption from the diet and greater release of iron from body stores. With more iron available, the bone marrow can produce more red blood cells.
By increasing the bioavailability of iron, testosterone ensures that the bone marrow has sufficient raw materials to produce red blood cells, which further contributes to elevated haematocrit levels.
Conversion to Estradiol:
Testosterone can be converted into estradiol, an estrogen hormone, through a process called aromatization. Estradiol has a significant role in promoting the proliferation and survival of hematopoietic stem cells in the bone marrow. These stem cells are crucial for the production of all blood cells, including red blood cells. By increasing the number of these stem cells, estradiol indirectly boosts red blood cell production.
Androgen Receptor Activation:
Testosterone binds to androgen receptors present in various tissues, including the bone marrow. When testosterone activates these receptors, it triggers a cascade of genetic and biochemical events that promote the production of red blood cells. This receptor-mediated action is a key factor in the testosterone-induced increase in haematocrit.
Clinical Implications
Given these mechanisms, it is clear that testosterone can significantly impact red blood cell production. This is why monitoring haematocrit levels in patients undergoing testosterone therapy is essential. Regular blood tests help detect any increases in haematocrit early, allowing for timely intervention to prevent complications such as blood clots, strokes, or heart attacks.
Managing Haematocrit Levels
To minimise the risks associated with high red blood cell counts, it is important to keep haematocrit levels at 50% or lower. Here are some strategies to manage haematocrit levels:
Dose Reduction: Lower the dose of testosterone to reduce its effect on red blood cell production. This can help keep haematocrit levels under control.
Increase Dose Frequency: Administering smaller doses more frequently can help maintain more stable testosterone levels and prevent spikes that may increase red blood cell production.
Switching Formulations: Consider switching from injectable testosterone to transdermal formulations (gels or patches), which may have a lower impact on haematocrit levels.
Regular Monitoring: Conduct regular blood tests to monitor haematocrit and haemoglobin levels. This should be done at baseline, 3, 6, and 12 months after starting therapy, and then annually.
Phlebotomy: For patients with significantly elevated haematocrit levels (over 54%) and symptoms, removing blood (phlebotomy) can be effective in lowering red blood cell counts quickly.
Reviewing Indications: Regularly reassess the need for continued testosterone therapy to ensure that it is necessary and beneficial. Discontinue therapy if the risks outweigh the benefits.
Hydration: Encourage patients to stay well-hydrated, as dehydration can concentrate blood and exacerbate high haematocrit levels.
This information is for educational purposes only and should not replace professional medical advice, diagnosis, or treatment. Individual health conditions and treatment responses can vary. Always consult your healthcare provider for advice tailored to your specific health needs. If you have any questions about a medical condition or treatment, seek advice from your doctor or a qualified health professional before starting any new healthcare regimen.