What Is TRT? Testosterone Replacement Therapy Basics Explained

Testosterone replacement therapy (TRT) is a medical treatment that supplements the body's natural testosterone production when levels are clinically low. It is prescribed by physicians to treat hypogonadism — a condition where the testes produce insufficient testosterone due to primary testicular dysfunction or secondary issues with the pituitary gland or hypothalamus. Symptoms of low testosterone include persistent fatigue, reduced muscle mass, increased body fat, decreased libido, mood changes, and reduced bone density. TRT aims to restore testosterone levels to the normal physiological range, alleviating these symptoms. This content is for educational purposes only. TRT is a prescription medical treatment that requires diagnosis and monitoring by a qualified healthcare provider.

TRT is available in several delivery methods, each with different pharmacokinetics and convenience profiles. Intramuscular injections (typically cypionate or enanthate esters) are the most common method, administered every 1-2 weeks or more frequently at lower doses for more stable blood levels. Subcutaneous injections using the same compounds have gained popularity for convenience and potentially smoother absorption. Transdermal gels and creams are applied daily to the skin, providing steady absorption but requiring care to avoid transferring the compound to others through skin contact. Transdermal patches are another daily option. Pellets implanted under the skin release testosterone over 3-6 months but require a minor in-office procedure. Each method has trade-offs in terms of level stability, convenience, cost, and monitoring requirements.

TRT requires regular blood work to ensure levels are within the target range and to monitor for potential side effects. Standard monitoring includes total and free testosterone levels, complete blood count (with particular attention to hematocrit and hemoglobin, as testosterone can increase red blood cell production), PSA (prostate-specific antigen), liver function, lipid panel, and estradiol. Hematocrit elevation is one of the most common side effects requiring attention, as significantly elevated levels increase blood viscosity and cardiovascular risk. Most physicians check labs before starting, 6-8 weeks after initiating or changing a dose, and every 6-12 months once stable.

TRT protocols vary based on the delivery method, individual response, and prescribing physician's approach. A common injectable protocol uses testosterone cypionate at 100-200 mg per week, often split into two injections for more stable levels. Some protocols include ancillary compounds to manage estrogen conversion or maintain fertility, though these decisions are highly individualized and managed by the prescribing physician. Protocol adherence — taking the correct dose at consistent intervals — significantly affects how stable blood levels remain between injections. Inconsistent dosing creates peaks and troughs that can cause symptoms to return during low points.

TRT is a long-term treatment that requires consistent adherence and regular monitoring. Tracking each dose, its timing, injection site, and any symptoms or side effects creates a valuable record for both personal reference and clinical consultations. When blood work shows unexpected results, a detailed dose log helps identify whether adherence issues, timing changes, or injection site variations might be contributing factors. Dosed is built for this kind of ongoing protocol tracking — logging each administration, rotating injection sites, scheduling reminders, and maintaining a history that you can review or share with your healthcare provider to keep your protocol optimized.