Secondary hypogonadism: when the signal, not the testes, is the problem

The hormone chain in brief

Testosterone production starts in the brain. The hypothalamus releases a hormone that prompts the pituitary to send LH and FSH into the blood. LH tells the testes to make testosterone; FSH supports sperm production. Testosterone and estrogen then feed back to the brain to slow the signal when levels are adequate.

A break at the top of that chain causes secondary hypogonadism. A break at the bottom, in the testes, causes primary hypogonadism.

How labs tell them apart

The Endocrine Society recommends diagnosing low testosterone only when you have symptoms and morning fasting total testosterone is unequivocally and consistently low, and it recommends measuring LH and FSH to distinguish primary from secondary causes. The AUA suggests 300 ng/dL as a reasonable cut-off and two early-morning measurements on separate days.

In primary hypogonadism, the brain is shouting but the testes are not answering, so LH and FSH are high. In secondary hypogonadism, LH and FSH are low or sit in the normal range when they should be elevated. The AUA also recommends checking prolactin when testosterone is low and LH is low or low-normal.

Symptoms that suggest low testosterone

Low testosterone symptoms are often vague and overlap with stress, poor sleep, depression and other conditions, which is why labs are essential. Common complaints include low sex drive, fewer morning erections, erectile difficulties, fatigue, low mood or irritability, reduced muscle strength, and increased body fat. Over time, low testosterone can also contribute to thinning bones and mild anemia.

Symptoms alone are not enough for a diagnosis, and a single low number is not enough either. Your clinician puts the two together, then looks for the cause before choosing a treatment. That careful sequence is what separates a sound plan from simply chasing a number.

Common causes in midlife

Many cases of secondary hypogonadism in men over 40 are functional, meaning the system is suppressed by something potentially reversible rather than permanently damaged.

• Excess body weight, particularly abdominal fat
• Obstructive sleep apnea and chronically short sleep
• Opioid pain medicines and some other prescription drugs
• Past or current anabolic steroid or testosterone use
• Heavy alcohol use
• Poorly controlled type 2 diabetes or serious illness
• Less often: high prolactin, pituitary tumors, iron overload or head injury

Fix what can be fixed first

Because so many causes are reversible, treating them can raise testosterone on its own. Weight loss, treating sleep apnea, reducing alcohol and reviewing medicines are all worth discussing before or alongside medication. In some men, these changes make medication unnecessary.

Some findings call for further evaluation rather than treatment: very low testosterone, high prolactin, headaches or vision changes that might suggest a pituitary problem, or signs of other hormone deficiencies. Your clinician will refer you for in-person endocrinology care or imaging if needed.

Where enclomiphene fits

Enclomiphene blocks estrogen feedback at the brain, increasing LH and FSH so the testes make more of their own testosterone. Phase III trials in overweight men aged 18 to 60 with secondary hypogonadism, defined by low morning testosterone and LH below 9.4 IU/L, found it raised testosterone, LH and FSH over 16 weeks while maintaining sperm concentration.

It does not fix the underlying cause, so lifestyle and medical factors still matter. It is not FDA-approved, long-term outcome data are lacking, and in 2022 an FDA advisory committee voted against adding it to the 503A bulks list. Testosterone therapy and FDA-approved alternatives such as off-label clomiphene remain options your clinician can discuss.

Monitoring on treatment

Expect repeat labs a few weeks after starting and periodically afterward, typically testosterone, LH, FSH, estradiol and hematocrit, plus PSA depending on age. The AUA suggests discussing whether to continue if testosterone normalizes but symptoms do not improve after three to six months.

The HealifyMD Enclomiphene / DHEA / Boron / Pregnenolone ODT is compounded by a licensed U.S. pharmacy. Compounded medications are not FDA-approved and are not reviewed by the FDA for safety, effectiveness or quality. It costs from $129/month, or $349 for three months ($116/month), with no membership fee, confirmed at the eligibility review; labs are priced separately.