High Hematocrit on TRT? Here’s How to Reduce It.

Testosterone replacement therapy (TRT) can boost your energy, sex drive, and muscle mass–all things that can help you feel like your best self. Unfortunately, TRT can also increase something you weren’t expecting–your hematocrit, the percentage by volume of red blood cells in your blood.

High hematocrit, also known as polycythemia or erythrocytosis, is linked with an increased risk of blood clots, heart attacks, and strokes in men taking TRT. ¹

The good news is that high hematocrit is easy to spot with a blood test. “Elevated hematocrit is a manageable but potentially serious side effect of TRT,” says urologist Joshua Calvert, M.D.

If you do have high hematocrit on TRT, you can take simple steps to reduce it.

About the Experts

Joshua Calvert, M.D., a board-certified urologist specializing in male infertility and low testosterone management.

Joseph Shatzel, M.D., a hematologist at Oregon Health & Science University.

Why TRT Might Cause High Hematocrit

TRT can raise hematocrit levels by increasing erythropoietin, a hormone that signals your bone marrow to produce more red blood cells.This is a usual “job” of testosterone.
Polycythemia develops when you produce too many red blood cells, the oxygen-carrying cells that give blood its crimson hue. When your blood gets oversaturated with red blood cells relative to white blood cells, platelets, and plasma, it blood gets too thick. This increases your risk of dangerous blood clots, including heart attacks and strokes.²
High hematocrit affects anywhere from 5 percent to 66 percent of cisgender men using TRT. ³ It’s one of the most common side effects of TRT and the top reason some users have to limit their doses. ⁴

“Hematocrit is often overlooked in men on TRT,” says Calvert. “While studies show that a significant proportion of men on TRT develop elevated hematocrit, this biomarker may be deprioritized compared to serum testosterone, PSA, or lipid profiles.”

There are two types of polycythemia. TRT causes the second kind below:

• Primary polycythemia happens when you develop a gene mutation in your bone marrow, where red blood cells form. “The sensor that tells your bone marrow how many red blood cells to make just gets kind of stuck on, like someone put a brick on the gas pedal,” says hematologist Joseph Shatzel, M.D. Primary polycythemia tends to occur in older adults–the average age at diagnosis is 64. ⁵
• Secondary polycythemia is triggered by other medical conditions, medications, or environmental factors. TRT can cause secondary polycythemia by revving up your production of erythropoietin. ⁶

High hematocrit can cause serious problems for your heart and circulatory system, so it’s important to consistently monitor your level with your prescriber.

The danger level depends on two things. One is how high your hematocrit goes before you catch it and bring it down. The other is your individual mix of risk factors, like smoking, sleep apnea, or chronic obstructive pulmonary disease (COPD), that add to your risk of a dangerous clot, says Calvert.

How to Know If You Have High Hematocrit

Your doctor can check your hematocrit level with a blood test. They should take a baseline hematocrit measurement as part of your workup before beginning TRT, says Calvert.

Why? New research suggests that men with higher-than-average hematocrit at baseline have more than double the risk of developing hematocrit levels 50 percent or higher when using TRT. Every one-unit increase in BMI was also linked with a 13 percent risk of developing high hematocrit.⁷

Your doctor should recheck your hematocrit every three to six months during the first year of TRT. After that, they should recheck it at least once a year—more if you have symptoms of high hematocrit (see below). Anyone with a history of blood clots or cardiovascular disease requires closer monitoring, says Calvert.

You’ll also need more frequent checks if you have a history of sleep apnea, chronic obstructive pulmonary disease (COPD), or smoking, says Calvert. All three can contribute to secondary polycythemia by depriving your body of oxygen and stimulating the production of extra red blood cells to oxygenate your tissues, says Shatzel.

Symptoms of high hematocrit

Common symptoms of high hematocrit in TRT users include:

• Headaches
• Fatigue
• Dizziness
• Facial flushing
• Paresthesia (tingly hands and feet)

In serious cases, chest pain or trouble breathing could mean a dangerous blood clot or heart issue—get medical help right away.

Sometimes the energizing effects of TRT mask the effects of high hematocrit. “Many people I see with testosterone-induced polycythemia don’t feel symptoms,” says Shatzel. This is why regular blood testing is critical when you take TRT—you can’t just rely on how you feel.

Blood test for high hematocrit

Regular blood testing can help you and your doctor spot a hematocrit level that’s trending upward.

Normal hematocrit values for men generally range between 41-50 percent, and are usually three times your hemoglobin levels. ⁸ A hematocrit above 52 percent is typically considered polycythemia.

The normal range for hematocrit in men can vary slightly by elevation, so your doctor might look for a different number if you live in the mountains (where hematocrit can be higher) versus on a coastal shoreline. The higher the altitude, the less oxygen in the environment—meaning you might require extra red blood cells to oxygenate your tissues, says Shatzel.

How to Lower Hematocrit While on TRT

You can safely reduce hematocrit on TRT through therapeutic phlebotomy, blood donation, asking your doctor to change your TRT dose or delivery system, and making lifestyle changes.

Therapeutic phlebotomy for high hematocrit

If your hematocrit hits 54 percent or higher, your doctor might recommend therapeutic phlebotomy, which is like a modern, scientifically vetted version of bloodletting. ⁹

Here’s how it works: Your doctor prescribes an amount of blood—usually 500 milliliters (mL), or one unit—to be removed from your body, says Shatzel. A nurse or phlebotomist inserts a needle into your arm to collect the blood. The session might feel like a cross between a blood test and a blood donation.

Therapeutic phlebotomy is highly effective for quickly reducing hematocrit in men on TRT, says Calvert. However, you might need multiple sessions to bring your hematocrit within the target range. ¹⁰

In a study review, 85 percent of people who received therapeutic phlebotomy for secondary polycythemia said their symptoms improved. Just two percent said the treatment made them feel worse. ¹¹

Another study showed a low risk of side effects. Some people felt dizzy or faint, but not more than expected in a group of people being stuck with needles. ¹²

Ask your doctor about how often you should have blood drawn to lower hematocrit on TRT. If you remove too much blood too often, you can develop low iron levels and fatigue says Shatzel.

Blood donation for high hematocrit

Another option for lowering hematocrit on TRT is giving blood at a blood donation center or blood drive. The process is similar to therapeutic phlebotomy and is safe for you and great for society, says Calvert.
Every blood donation center has its own screening rules, but in general, high hematocrit from TRT won’t disqualify you from donating, says Shatzel. Research shows that blood donors using TRT donate more often than other blood donors. ¹³

Blood donations take place at blood banks, schools, or workplaces. You’ll likely give 500 mL of blood, or one unit, the same amount usually recommended in therapeutic phlebotomy. Since your doctor won’t be there to document the procedure, be sure you give them a heads-up about when and how much you donated.
“This information allows us to adjust treatment plans appropriately, including the frequency of blood testing and therapeutic phlebotomy scheduling,” says Shatzel. Tracking donations helps ensure we maintain optimal blood counts and avoid over- or under-treatment.”
Another difference between therapeutic phlebotomy and blood donation is where the blood goes, says Shatzel. Since therapeutic phlebotomy is a medical procedure, the blood is usually discarded. When you donate blood, that blood usually goes to help someone else, so long as it passes the post-donation screening for infectious disease. ¹⁴

Adjust TRT Delivery

If high hematocrit persists, your doctor might change your TRT delivery method, especially if you’ve been using intramuscular injections.

“Creams and subcutaneous injections provide a more stable release of testosterone compared to intramuscular injections, which often result in serum testosterone peaks and troughs,” says Calvert. “These peaks are associated with increased erythropoiesis and hematocrit elevation.”

Creams and subcutaneous methods may require more frequent dosing to maintain steady levels, but they’re as effective as intramuscular injections in managing symptoms when used correctly, he says.

Lower TRT Dose

Your doctor might recommend lowering your TRT dose to reduce hematocrit. Don’t make any changes on your own, as this can lead to dangerous fluctuations in testosterone levels, says Calvert. Having too much testosterone can exacerbate hematocrit elevation, while having too little may result in a recurrence of the symptoms of low testosterone that led you to take TRT in the first place.

If your hematocrit reaches 54 percent, your doctor might recommend temporarily stopping TRT to lower your hematocrit. Once your hematocrit is back in the normal range and other causes (like sleep apnea) have been addressed or ruled out, you might be cleared to restart TRT. ¹⁵

Medications for high hematocrit

A few medications can reduce hematocrit, but they’re usually used in primary polycythemia, not secondary polycythemia, says Shatzel.

In secondary polycythemia from TRT, medications are reserved for complex cases or when other treatments aren’t working, says Calvert. For example, your doctor might recommend low-dose aspirin to reduce your risk of blood clots from elevated hematocrit. ¹⁶

Supplements for high hematocrit

If you have high hematocrit, it’s important to tell your doctor about any dietary supplements you take. Sometimes polycythemia overlaps with hemochromatosis and excess blood levels of iron, so iron supplements could exacerbate testosterone-induced polycythemia.

Lifestyle changes for high hematocrit

Therapeutic phlebotomy, blood donation, or changing your TRT dose or delivery method are the most effective ways to reduce hematocrit. Lifestyle changes can also help.

• Stay hydrated. Dehydration is a common cause of temporarily elevated hematocrit, says Calvert. When you don’t drink enough water, your blood plasma volume decreases, increasing the proportion of red blood cells. ¹⁷ The other benefit: When there’s more fluid in your veins, the phlebotomist can draw your blood with less poking and prodding. ¹⁸
• Don’t smoke. Lighting up puts your body in a state of chronic hypoxia–low levels of oxygen in your tissues–and erythropoietin stimulation, says Calvert. Research suggests that within less than a year of quitting, smokers’ hematocrit levels drop to levels close to nonsmokers.¹⁹
• Treat sleep problems. If you snore, get checked for sleep apnea. Treating sleep apnea can improve your oxygen levels and decrease red blood cell generation, says Calvert. One study showed that people who received continuous positive airway pressure (CPAP) treatment for sleep apnea reduced their hematocrit by 1.1 percent. ²⁰ Plus, managing chronic health problems like sleep apnea has also been linked to better symptom improvement on TRT. ²¹

How Often to Give Blood on TRT

You can donate blood every eight weeks, up to six times a year, says Calvert. Again, make sure your doctor knows how often you’re donating so they can recheck your hematocrit levels if needed.

If you opt for therapeutic phlebotomy, you might be able to give blood more often. “Lots of places that do therapeutic phlebotomy will take blood more often and sometimes just dispose of the blood–this is also commonly utilized by men who can’t donate,” says Calvert. “They won’t take your blood if your hematocrit is too low, so it’s a foolproof way of staying in a healthy range.”