You should get your testosterone checked if you’re experiencing persistent symptoms like low sex drive, erectile difficulties, unusual fatigue, or loss of muscle mass, especially if you’re over 40 or have conditions like obesity or type 2 diabetes. The test itself needs to be done under specific conditions to get an accurate reading: fasting, early in the morning, and repeated at least once to confirm the result.
Symptoms That Warrant Testing
Sexual symptoms are the strongest signal. A noticeably reduced sex drive, loss of morning erections, or difficulty getting and maintaining erections are the most specific indicators of low testosterone. These don’t guarantee your levels are low, but they’re the symptoms most closely tied to a hormonal cause rather than something else.
Beyond sexual function, low testosterone can show up as a decrease in muscle strength and mass, reduced physical endurance, increased body fat (particularly around the midsection), mood changes like persistent low energy or irritability, and difficulty concentrating. None of these symptoms alone is diagnostic, but when several cluster together, testing makes sense. If you’ve been chalking up a combination of these to “just getting older,” a blood test can tell you whether testosterone is part of the picture.
Health Conditions That Raise Your Risk
Certain conditions are strongly linked to low testosterone and justify screening even before symptoms become obvious. Men with obesity, metabolic syndrome, and type 2 diabetes consistently have lower total and free testosterone levels. The relationship runs both directions: low testosterone predicts the development of metabolic syndrome and type 2 diabetes, and those conditions further suppress testosterone. If you carry significant excess weight or have been diagnosed with insulin resistance, asking for a testosterone check is reasonable.
Sleep apnea, chronic opioid use, and long-term glucocorticoid therapy (often prescribed for autoimmune conditions or severe allergies) also suppress testosterone through different pathways. Men on methadone maintenance therapy experience particularly pronounced drops. If any of these apply to you, testosterone should be part of your routine bloodwork conversation.
Age and Natural Decline
Testosterone doesn’t fall off a cliff at a certain age. In men between 40 and 70, total testosterone declines at roughly 0.4% per year, while the more biologically active “free” form drops faster, around 1.3% per year. That gradual slide means a man in his late 50s may have meaningfully lower levels than he did at 30, but still fall within the normal range. Age-related decline alone isn’t a reason to test. The trigger should be symptoms that affect your quality of life combined with that natural downward trend.
There’s no standard age to begin routine screening. Most guidelines recommend testing when symptoms prompt it rather than at a fixed birthday. That said, if you’re over 45 and noticing changes in energy, body composition, or sexual function, bringing it up with your doctor is worthwhile.
How to Get an Accurate Result
Testosterone follows a daily rhythm, peaking between 7:00 and 10:00 a.m. and dropping to its lowest point in the evening. Current recommendations call for a blood draw between 8:00 and 9:00 a.m. to catch levels near their peak and reduce variability between tests. If your blood is drawn in the afternoon, your result could look artificially low.
You should also fast overnight before the test. Eating causes a real, measurable drop in testosterone. In one study, a standard meal lowered total testosterone by an average of 26% from baseline, and a glucose drink lowered it by 18%. The decline starts within 20 minutes of eating and hasn’t fully recovered even two hours later. Over half the men who ate a mixed meal temporarily dipped below the clinical threshold for low testosterone, despite having normal levels while fasting. Skipping breakfast on the morning of your test isn’t optional; it directly affects whether your result is accurate.
What Gets Measured
The first test ordered is almost always total testosterone, which measures both the testosterone bound to proteins in your blood and the small fraction floating freely. Most of your testosterone is bound to proteins and not readily available for your body to use. Free testosterone, the unbound portion, is what actually builds muscle and bone.
If your total testosterone comes back borderline or low, your doctor will often order a free testosterone level along with a protein called sex hormone-binding globulin (SHBG) to get a clearer picture. Some men have normal total testosterone but low free testosterone because too much of it is tied up by binding proteins. This is especially common in older men and those with obesity.
Why You’ll Need More Than One Test
A single low result isn’t enough for a diagnosis. Testosterone levels fluctuate day to day based on sleep quality, stress, recent illness, and other factors. The American Urological Association uses a total testosterone level below 300 ng/dL as the diagnostic cutoff, but requires at least two separate morning fasting blood draws to confirm the finding. If your first test comes back at 280, the next step is repeating it on a different day under the same conditions, not starting treatment.
Timing matters here too. You should not get tested during an acute illness, whether that’s the flu, a bad infection, or recovery from surgery. Illness can temporarily but significantly suppress testosterone, and a result taken during that window doesn’t reflect your actual baseline. Wait until you’ve fully recovered before testing.
When Women Should Get Tested
Testosterone testing isn’t only for men. Women produce testosterone in smaller amounts, and levels that are too high or too low can cause noticeable problems. The most common reason for testing in women is suspected polycystic ovary syndrome (PCOS), which affects hormone balance and ovulation.
Signs that point toward excess testosterone in women include coarse hair growth in typically male patterns (upper lip, chin, chest, back), persistent or severe acne that continues into adulthood, thinning hair on the scalp in a pattern resembling male baldness, and irregular or absent menstrual periods. An adolescent with moderate to severe acne should be evaluated for PCOS, and adult women whose acne persists or develops after their teenage years deserve a closer look as well. Infertility, recurrent early miscarriage, and darkened skin patches in body folds (a sign of insulin resistance) are also associated features.
Women experiencing unexplained low libido, fatigue, or loss of bone density may be tested for low testosterone, particularly around and after menopause, though guidelines for this are less firmly established than for men.