Low luteinizing hormone (LH) almost always traces back to a problem with signaling in the brain, not with the ovaries or testes themselves. Your hypothalamus and pituitary gland work together to produce LH, and anything that disrupts that chain of communication, from chronic stress to certain medications to a pituitary tumor, can drive levels down. The specific cause matters because it determines whether the fix is a lifestyle change, hormone therapy, or something else entirely.
How LH Production Works
LH starts with a signal from your hypothalamus, a small region at the base of the brain that acts as a control center for many body functions. The hypothalamus releases a trigger hormone called GnRH in rhythmic pulses throughout the day. Each pulse tells the pituitary gland to produce and release LH (along with a partner hormone, FSH). In men, LH signals the testes to make testosterone. In women, LH and FSH together drive ovulation and regulate the menstrual cycle.
Because this system depends on precise, pulsatile signaling, it’s vulnerable at multiple points. A problem with the hypothalamus means fewer GnRH pulses. A problem with the pituitary means GnRH arrives but LH doesn’t get made. Either way, LH drops.
Normal LH Ranges
LH is measured in international units per milliliter (IU/mL). For men, the normal range is roughly 1.24 to 7.8 IU/mL. For women, it depends heavily on where you are in your menstrual cycle:
- Follicular phase (first half of your cycle): 1.68 to 15 IU/mL
- Mid-cycle peak (around ovulation): 21.9 to 56.6 IU/mL
- Luteal phase (second half): 0.61 to 16.3 IU/mL
A single low reading doesn’t always mean something is wrong. LH is released in pulses, so a blood draw taken between pulses might catch a trough. If your doctor suspects low LH, they’ll typically retest or look at it alongside FSH, testosterone, or estrogen levels to get the full picture.
Stress, Undereating, and Overexercising
The most common reason for low LH in younger women is a combination of too few calories, too much exercise, and high stress. When your body senses an energy deficit, your hypothalamus essentially goes into survival mode. It scales back processes that aren’t immediately essential for keeping you alive, and reproduction is one of the first to go. GnRH pulses slow down, LH and FSH drop, ovulation stops, and periods disappear. Doctors call this functional hypothalamic amenorrhea.
Research on premenopausal women shows how directly energy balance affects LH. In one study, three months of caloric restriction combined with exercise reduced LH pulse frequency by about 0.18 pulses per hour, a meaningful drop in a system that relies on precise timing. Even 48 hours of fasting is enough to measurably decrease LH pulses in both men and women. The body closely ties reproductive signaling to fuel availability, and the hunger hormone ghrelin appears to be part of the link: rising ghrelin levels correlated with falling LH pulse rates.
This isn’t limited to people with eating disorders, though anorexia nervosa is one of the most severe examples. Recreational athletes, people on aggressive diets, and anyone experiencing prolonged psychological stress can see this effect. The good news is that it’s often reversible. Women with this type of LH suppression can resume normal menstrual cycles by restoring their weight to at least 85% of their ideal body weight and reducing excessive exercise.
Medications That Suppress LH
Several categories of medication directly lower LH by interfering with the hypothalamic-pituitary signaling chain:
- Opioids: Both prescription painkillers and heroin suppress GnRH release, often significantly. Long-term opioid use is one of the most common drug-related causes of low LH in men, frequently leading to low testosterone, reduced sex drive, and fatigue.
- Glucocorticoids: High doses or prolonged courses of steroid anti-inflammatory drugs can dampen the entire hormonal axis.
- Anabolic steroids and testosterone: External testosterone tells the brain there’s already plenty, so it shuts down its own GnRH and LH production. This is why men who use testosterone replacement or anabolic steroids for muscle building often become infertile while on them.
- Hormonal contraceptives: Birth control pills, patches, and hormonal IUDs are designed to suppress LH (particularly the mid-cycle surge) to prevent ovulation. A low LH reading while on contraceptives is expected, not a problem.
Pituitary and Hypothalamic Conditions
When low LH isn’t explained by lifestyle or medication, the cause is often structural or disease-related. A pituitary tumor (adenoma) is one of the more common culprits. Even benign tumors can compress the normal pituitary tissue and reduce its ability to produce LH. Larger tumors, those over 1 cm, may also press on the optic nerves and affect vision.
High prolactin is another frequent finding. Prolactin is a pituitary hormone that, when elevated, directly suppresses GnRH pulses. Prolactin can rise because of a prolactin-secreting tumor, certain psychiatric medications, or other causes. Treatment with a dopamine agonist often brings prolactin back down and restores normal LH levels.
Other conditions that can damage the pituitary or hypothalamus and reduce LH include head injury, brain surgery, radiation therapy to the head, severe infections, and iron overload conditions like hemochromatosis. Chronic inflammatory diseases can also suppress the axis over time.
Obesity and Low LH in Men
Carrying significant excess weight is a recognized risk factor for low LH in men. Fat tissue converts testosterone into estrogen, and higher estrogen levels feed back to the brain, telling it to reduce GnRH and LH output. The result is a cycle: obesity lowers LH, lower LH means less testosterone, and lower testosterone makes it easier to gain more fat. Weight loss can partially or fully reverse this pattern in many men.
Genetic Causes
Some people are born with conditions that prevent normal LH production. The best known is Kallmann syndrome, an inherited condition where the hypothalamus doesn’t produce enough GnRH. Children with Kallmann syndrome typically don’t enter puberty on their own. A hallmark feature is a reduced or absent sense of smell, which helps distinguish it from other forms of delayed puberty. A related condition, called normosmic idiopathic hypogonadotropic hypogonadism, involves the same LH deficiency without the smell component. Both are rare but treatable.
What Low LH Feels Like
The symptoms of low LH are really the symptoms of whatever hormone it’s failing to stimulate. In men, that means low testosterone: reduced sex drive, loss of muscle mass, thinning body or facial hair, fatigue, and difficulty conceiving. In women, it means low estrogen and absent ovulation: missed or irregular periods, infertility, and over time, bone thinning. Both men and women may experience fatigue, weakness, and decreased appetite if the underlying cause is a broader pituitary problem affecting multiple hormones.
In adolescents, low LH shows up as delayed puberty. Girls who haven’t begun developing by age 13 and boys who haven’t by age 14 may be evaluated with LH testing as part of the workup.
How Low LH Is Treated
Treatment depends entirely on the cause and on whether you’re trying to conceive.
If the root cause is undereating, overexercising, or stress, the first-line approach is restoring energy balance. No medication can fully replace what adequate nutrition and rest do for the hormonal axis. For many women, simply gaining weight and reducing training intensity is enough to restart normal cycles.
If the cause is a medication, stopping or switching the drug (when possible) often allows LH to recover on its own. Men who stop anabolic steroids, for example, typically see LH return over weeks to months, though recovery can be slow after long-term use.
When LH stays low and fertility is the goal, the approach differs by sex. Men may receive a pump that delivers GnRH in natural pulses to restart the system from the top, or they may take a medication that stimulates the pituitary to release more LH and FSH on its own. Women trying to conceive typically undergo ovulation induction with injectable hormones that essentially replace what LH and FSH would normally do.
For people who aren’t trying to conceive, hormone replacement fills the gap downstream. Men receive testosterone to restore sex drive, energy, and muscle mass. Women receive estrogen to protect bone density, with progesterone added cyclically to protect the uterine lining. These don’t fix the underlying LH problem, but they address the consequences.
Pituitary tumors that are large, growing, or affecting vision may require surgery, most often performed through the nose using a minimally invasive approach. Smaller prolactin-producing tumors are usually managed with medication alone. People with broader pituitary failure may need lifelong replacement of thyroid and adrenal hormones in addition to sex hormones.