What prolactin is and the normal range for men
Prolactin is a hormone made by the pituitary gland at the base of the brain. Its main known job is milk production, and MedlinePlus notes there is no known normal function for it in men. It lists a typical male value of less than 20 ng/mL, and ranges vary by lab.
High prolactin still matters for men because it can interfere with the testicles. MedlinePlus’s prolactin test page explains that a high level can lower sex drive and cause erectile dysfunction, which is why it shows up in testosterone and libido workups.
Why a mildly high result is often not disease
A prolactin a little above the range is common and usually has an everyday explanation. MedlinePlus lists emotional or physical stress, recent exercise, sex, a high-protein meal and recent chest or nipple stimulation as causes of temporary rises.
| Cause | Why it raises prolactin | What to do |
|---|---|---|
| Stress, including the blood draw | Prolactin is a stress-responsive hormone | Repeat seated and calm |
| Recent exercise or sex | Short-lived rise | Skip both before the repeat |
| High-protein meal | Short-lived rise | Repeat fasting |
| Draw timed close to waking | Prolactin varies through the day | Draw a few hours after waking |
| Medicines | Antidepressants, metoclopramide, opioids, risperidone and others | Review the list; do not stop on your own |
| Macroprolactin | An inactive, slowly cleared form counted by many assays | Ask the lab to check for it |
The Endocrine Society’s hyperprolactinemia guideline treats a single high value as meaningful only when the sample was drawn without excessive venipuncture stress, and suggests checking for macroprolactin in people whose high prolactin causes no symptoms. MedlinePlus also lists marijuana, H2 blockers, verapamil and estrogens among substances that can raise it.
Repeat at rest before imaging
The first response to a mildly high prolactin is a better-controlled repeat, not a scan. MedlinePlus says that, depending on symptoms and history, your provider may test again to see whether the level stays high, and that a repeat may be done in the morning after an 8-hour fast. Its test page adds that samples are usually scheduled three to four hours after waking, because prolactin changes through the day.
A clean repeat looks like this:
- Fast for about 8 hours, and skip the protein shake.
- Avoid exercise and sex the day before and the morning of the test.
- Arrive early enough to sit quietly for a while before the draw.
- Bring a full list of medicines and supplements.
- Ask whether macroprolactin can be checked if the value is still high.
If the repeat is normal, the first value was most likely a temporary rise. If it is still high, other causes such as an underactive thyroid or kidney disease, both listed by MedlinePlus, are checked before attention turns to the pituitary.
When a high prolactin needs pituitary imaging
Imaging is for prolactin that stays high after a careful repeat, or for a high value with warning signs. The Endocrine Society testosterone guideline recommends pituitary MRI in men with low testosterone and persistently high prolactin, a total testosterone under 150 ng/dL, loss of several pituitary hormones, or symptoms of a mass such as new headaches or vision changes.
The usual cause found is a prolactinoma, a benign pituitary tumor that MedlinePlus says is usually treated with medicine. Our page on high prolactin in men covers treatment, and pituitary MRI before TRT explains when a scan comes up during a testosterone workup.
A sudden, severe headache with vision loss or double vision is an emergency. Call 911 or go to an emergency room rather than waiting for repeat labs.
Prolactin in the testosterone workup
Prolactin earns its place when low testosterone comes with a low or normal LH, the pattern that points to the pituitary rather than the testes. The AUA guideline recommends measuring prolactin in men with low testosterone and low or low-normal LH, and the Endocrine Society asks for prolactin and iron saturation in men with this secondary form of low testosterone.
Our pages on low testosterone with low LH, the LH blood test and secondary hypogonadism explain how that pattern is recognized.
How prolactin testing fits at Ultimate Male
Prolactin is not one of the four tests in our TRT pre-screening panel, which covers total testosterone, estradiol, PSA and a complete blood count. Whether it belongs in your workup depends on your LH result, symptoms such as low libido or weaker erections, and your medicine list, so ask on the free 10-minute call whether it should be included with your draw at San Gabriel or Downey.
If a result comes back high, your provider first looks at how the sample was taken and what you take, then explains whether a calm repeat, a macroprolactin check, an endocrinology referral or imaging is the sensible next step. See the panels we offer on our preventative blood testing page.
