They Never Checked Your Testosterone

Your body runs on a hormone system that works like a chain of commands, and when one link in that chain breaks, the signal never reaches its destination.

The chain starts in the brain, specifically in a region called the hypothalamus, which sends out a signal called GnRH, a messenger that tells the pituitary gland to release LH, which then travels through the bloodstream to the testes and tells them to produce testosterone. When testosterone is produced in sufficient amounts, it signals back to the brain to slow down the signal. The whole system is self-regulating, like a thermostat that reads the room temperature and adjusts the heat accordingly.

When that production drops below what your body needs, everything downstream from testosterone starts to fail quietly.

And that is where the problem begins, because the symptoms of low testosterone do not announce themselves as a hormone problem. They announce themselves as a mood problem.

You stop caring about things that used to matter. Your energy is gone by mid-morning. Your sleep is broken. Your thinking is slower. You feel a flatness that is hard to explain to anyone. These are the same symptoms listed in the diagnostic criteria for major depressive disorder, and most doctors are trained to treat the symptoms in front of them, which means the answer is usually an antidepressant.

A study published in the Archives of General Psychiatry followed a large group of older men and found that those with low testosterone had a 4.2 times higher hazard ratio for being diagnosed with depression. That is not a small signal. That is nearly a fourfold increase in risk, and most of those men were never evaluated for a hormonal cause before they were given a psychiatric diagnosis.

The testing gap makes this worse. Research published in the Journal of Sexual Medicine looked at a large health system and found that only 3.2 percent of men had ever been tested for testosterone. Not 3.2 percent of men with symptoms. 3.2 percent of all men. Which means the vast majority of men walking into a doctor's office with fatigue, low mood, and cognitive fog are being evaluated for everything except the hormone that directly governs those systems.

And the men who are most likely to have low testosterone are the ones most likely to never be tested. The HIM study, which looked at men 45 and older in primary care settings, found that 38.7 percent of them had testosterone levels in the hypogonadal range. That is more than one in three men in that age group, and it is happening in the exact population where depression diagnoses are also climbing.

Here is where the situation becomes more complicated. Certain antidepressants, specifically a class called SSRIs, which stands for selective serotonin reuptake inhibitors and which work by increasing the availability of serotonin in the brain, appear to suppress testosterone on their own. Research published in 2025 found that SSRIs decrease serum testosterone levels and reduce sperm production in men. The precise mechanism is still being studied, but the pattern is consistent enough across the literature to take seriously.

So the sequence for some men looks like this. Testosterone drops. Mood drops. A doctor prescribes an antidepressant without testing hormones. The antidepressant suppresses testosterone further. The patient feels worse, or feels only partially better, and nobody knows why, because nobody measured the hormone that may have started the whole cascade.

The reason this matters is not just diagnostic, it is about whether the treatment can actually work. A systematic review and meta-analysis published in JAMA Psychiatry pooled data from 27 randomized controlled trials involving 1,890 men and found that testosterone treatment significantly reduced depressive symptoms across that population. That is a large and well-controlled dataset, and the direction of the finding is consistent. For men whose depression is being driven by low testosterone, treating the serotonin system does not fix the underlying problem, because serotonin was never the problem.

This is not an argument against antidepressants. For a meaningful portion of men, depression is a true serotonin or norepinephrine dysregulation problem, and SSRIs are the right tool for that. The issue is not the medication. The issue is the order of operations.

You cannot know what you are treating if you have not measured what is broken.

Testosterone also interacts with the brain in ways that go beyond mood. It affects something called neurogenesis, which is the process by which the brain produces new neurons, particularly in the hippocampus, the region responsible for memory consolidation and emotional regulation. Low testosterone is associated with reduced hippocampal volume and impaired neurogenesis, which may explain why cognitive fog and emotional blunting often travel together with the low mood in testosterone-deficient men. These are not separate symptoms. They are different expressions of the same upstream failure.

The practical takeaway is straightforward. If you have been experiencing low mood, low energy, reduced drive, poor sleep, or cognitive fog and no one has ever run a testosterone panel, that panel needs to happen before the conversation about depression treatment goes further. A basic test measures total testosterone in the blood, and it is a standard lab draw. Some men will need additional markers like free testosterone, LH, and SHBG, which is a protein that binds testosterone and makes it unavailable to tissue, to get a complete picture. But the first step is simply getting a number.

If the number is low and you are also experiencing the symptoms, then you have a direction to investigate. If the number is normal, the conversation about depression can continue with actual information rather than assumptions.

The medical system is good at treating what it measures, and the problem is simply that for too long, it has not been measuring this.

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References

1. Shores MM, et al. Increased incidence of diagnosed depressive illness in hypogonadal older men. Archives of General Psychiatry. 2004;612:162-167. Men with low testosterone had a 4.2x higher hazard ratio for depression. Source
2. Malik RD, et al. Are we testing appropriately for low testosterone?: Characterization of tested men and compliance with current guidelines. Journal of Sexual Medicine. 2015;121:66-75. Only 3.2% of men in a large health system had ever been tested for testosterone. Source
3. Oliveira RA, et al. Selective Serotonin Reuptake Inhibitors SSRIs: Effects on male fertility. JBRA Assisted Reproduction. 2025;292:351-358. SSRIs decrease serum testosterone levels and reduce sperm production. Source
4. Walther A, et al. Association of Testosterone Treatment With Alleviation of Depressive Symptoms in Men: A Systematic Review and Meta-analysis. JAMA Psychiatry. 2019;761:31-40. 27 RCTs n=1,890 showed testosterone significantly reduces depressive symptoms. Source
5. Mulligan T, et al. Prevalence of hypogonadism in males aged at least 45 years: the HIM study. International Journal of Clinical Practice. 2006;607:762-769. 38.7% of men 45+ in primary care had hypogonadal testosterone levels. Source

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