Prolactin Total and Monomeric (Macroprolactin) Biomarker Testing
It measures total prolactin and the active monomeric fraction to clarify true hyperprolactinemia, with easy ordering and Quest-based labs via Vitals Vault.
With Vitals Vault, you have access to a comprehensive range of biomarker tests.
Prolactin is a hormone best known for supporting breast milk production, but it also interacts with your reproductive hormones, sexual function, and overall pituitary signaling.
A “total prolactin” result can be confusing because some people have a benign form called macroprolactin that can raise the total number without causing symptoms. The Prolactin Total and Monomeric test is designed to separate the biologically active portion (monomeric prolactin) from the inactive portion.
If you are trying to understand symptoms like missed periods, unexpected breast discharge, infertility, low libido, or erectile dysfunction, this test can help you and your clinician decide whether prolactin is truly part of the picture or whether the elevation is likely an artifact.
Do I need a Prolactin Total and Monomeric test?
You may want this test if you have symptoms that can be linked to elevated prolactin (hyperprolactinemia), such as irregular or absent periods, infertility, decreased libido, erectile dysfunction, or milky nipple discharge when you are not breastfeeding (galactorrhea). It is also commonly used when a routine “total prolactin” test comes back high and you need to know whether the active fraction is actually elevated.
This test is especially helpful if your total prolactin is mildly to moderately high but you do not have typical symptoms. In that situation, macroprolactin can be the reason, and identifying it can prevent unnecessary imaging, repeat blood draws, or medication changes.
You may also need prolactin testing if you have a known pituitary condition (such as a prolactinoma), if you are monitoring response to dopamine agonist therapy (for example, cabergoline or bromocriptine), or if you are taking medications that can raise prolactin and you are developing symptoms.
Testing supports clinician-directed care and follow-up planning, but it cannot diagnose a pituitary tumor or any single condition on its own.
This is a blood test typically performed in a CLIA-certified laboratory; results should be interpreted with your symptoms, medications, and other hormone tests rather than used as a standalone diagnosis.
Lab testing
Order labs to measure Prolactin (Total and Monomeric)
from $561.01 at Quest Diagnostics
About 1 week
Schedule online — results typically within a week
Clear next steps
Guidance included, with follow-up care available
HSA / FSA
Eligible for pre-tax health spending accounts
Get this test with Vitals Vault
Vitals Vault lets you order Prolactin Total and Monomeric testing directly, so you can move from “I have a confusing prolactin result” to a clearer next step without waiting weeks for a new order.
After your results are in, you can use PocketMD to review what “total” versus “monomeric” means for your situation, what follow-up labs are commonly paired with prolactin, and when a repeat draw is worth doing (for example, if stress, sleep loss, or a recent workout may have influenced the number).
If you are already working with a clinician, you can bring a more specific result to that visit. If you are not, PocketMD can help you organize questions and decide whether broader hormone or pituitary-related testing would add clarity before you retest.
- Order online and test through a national lab network
- PocketMD guidance to help you interpret total vs monomeric results
- Easy re-ordering for confirmatory testing or trend tracking
Key benefits of Prolactin Total and Monomeric testing
- Distinguishes true hyperprolactinemia from macroprolactin-related “false” elevations.
- Helps explain reproductive and sexual symptoms when prolactin is suppressing gonadotropin signaling.
- Reduces unnecessary follow-up when total prolactin is high but monomeric prolactin is normal.
- Supports smarter next steps, such as targeted pituitary evaluation only when the active fraction is elevated.
- Provides a clearer baseline for monitoring treatment response in known prolactin disorders.
- Improves interpretation when medications, stress, or recent illness may be affecting total prolactin.
- Pairs well with companion hormone tests so you can interpret prolactin in context rather than in isolation.
What is Prolactin Total and Monomeric?
Prolactin is a hormone made by your pituitary gland. In addition to its role in lactation, prolactin interacts with the hypothalamus and pituitary to influence reproductive hormones. When prolactin is truly elevated, it can lower gonadotropin-releasing hormone (GnRH) signaling, which may reduce luteinizing hormone (LH) and follicle-stimulating hormone (FSH). That downstream effect can contribute to irregular ovulation, low testosterone, and related symptoms.
A standard prolactin test measures total prolactin in your blood. However, prolactin circulates in different forms. The most biologically active form is monomeric prolactin. Another form, macroprolactin, is a larger complex (often prolactin bound to immunoglobulin) that can register as “high prolactin” on some assays but usually has less biologic activity.
The Prolactin Total and Monomeric test reports both the total prolactin and an estimate of the monomeric (active) fraction. This helps clarify whether an elevated total result is likely to be clinically meaningful.
You will still need clinical context. Pregnancy, breastfeeding, thyroid status, kidney function, pituitary conditions, and certain medications can all affect prolactin, and the same total number can mean different things depending on what else is going on.
Why macroprolactin matters
Macroprolactin can cause persistent elevation of total prolactin without the typical symptoms of hyperprolactinemia. If your monomeric prolactin is normal, many clinicians treat the result as a benign lab finding and focus on other causes of symptoms.
When timing and conditions affect the draw
Prolactin can rise with stress, sleep disruption, nipple stimulation, sex, and intense exercise. If your result is borderline high, repeating the test under calmer conditions (often in the morning after a normal night of sleep) can be more informative than reacting to a single number.
What do my Prolactin Total and Monomeric results mean?
Low prolactin levels
Low prolactin is usually not a problem by itself and often does not require treatment. In some situations, very low prolactin can be seen with broader pituitary under-function (hypopituitarism), especially if other pituitary hormones are also low. If you have symptoms like fatigue, low libido, or menstrual changes, the key is whether other pituitary or thyroid markers are abnormal rather than prolactin alone.
In-range (optimal) prolactin levels
An in-range total prolactin with an in-range monomeric prolactin generally suggests prolactin is not driving your symptoms. If you are evaluating fertility, menstrual irregularity, or sexual symptoms, your clinician may look next at thyroid function, gonadotropins (LH/FSH), estradiol or testosterone, and sometimes adrenal-related markers. If you are monitoring a known prolactin disorder, “optimal” means your current plan may be working, but trends over time and symptoms still matter.
High prolactin levels
A high total prolactin result can be meaningful or misleading depending on the monomeric fraction. If total prolactin is high and monomeric prolactin is also high, that pattern supports true hyperprolactinemia, which can be associated with medication effects, hypothyroidism, kidney disease, chest wall stimulation, or pituitary causes such as a prolactinoma. If total prolactin is high but monomeric prolactin is normal (suggesting macroprolactin), the elevation is often less clinically significant, and follow-up may focus on symptoms and repeat testing rather than aggressive workup.
Factors that influence prolactin
Prolactin is sensitive to the conditions around the blood draw. Stress, poor sleep, recent intense exercise, sexual activity, and nipple or chest wall stimulation can raise levels temporarily. Pregnancy and breastfeeding raise prolactin physiologically, and hypothyroidism can increase prolactin through higher thyrotropin-releasing hormone (TRH) signaling. Several medications can elevate prolactin, including antipsychotics, some antidepressants, opioids, and certain nausea medications; always review your medication list with your clinician before interpreting a high result.
What’s included
- Prolactin, Monomeric
- Prolactin, Total
Similar tests and related panels
Frequently Asked Questions
What is the difference between total prolactin and monomeric prolactin?
Total prolactin is the overall amount measured by a standard assay. Monomeric prolactin is the smaller, biologically active form that more directly relates to symptoms. This test helps you see whether a high total result reflects true elevation of the active hormone or a benign increase from macroprolactin.
What is macroprolactin and should I worry about it?
Macroprolactin is a larger prolactin complex that can raise total prolactin results on some lab methods but often has limited biologic activity. If your monomeric prolactin is normal and you do not have typical symptoms, macroprolactin is often treated as a benign finding. Your clinician may still recommend a repeat test or additional labs depending on your history.
Do I need to fast for a prolactin test?
Fasting is not always required, but consistency helps. Many clinicians prefer a morning draw after a normal night of sleep and avoiding strenuous exercise and sexual activity beforehand, because prolactin can rise with stress and stimulation. Follow the collection instructions provided with your order.
Can stress or exercise raise prolactin?
Yes. Acute stress, sleep disruption, intense exercise, and nipple or chest wall stimulation can temporarily increase prolactin. If your result is borderline high, repeating the test under calmer, standardized conditions can help confirm whether the elevation is persistent.
What medications can increase prolactin levels?
Medications that reduce dopamine signaling are common causes, including many antipsychotics and some anti-nausea drugs. Opioids and some antidepressants can also raise prolactin in certain people. Do not stop any medication on your own; instead, review your list with your prescribing clinician if prolactin is elevated and you have symptoms.
If my prolactin is high, do I need a pituitary MRI?
Not automatically. The decision usually depends on how high the monomeric (active) prolactin is, whether the elevation persists on repeat testing, your symptoms, and whether there is an obvious cause such as medication use, pregnancy, or hypothyroidism. This test can reduce unnecessary imaging when macroprolactin is the main reason total prolactin is elevated.
How soon should I retest prolactin if it is abnormal?
That depends on the pattern and likely cause. If the result is mildly high and you had potential confounders (poor sleep, stress, recent exercise), a repeat morning test is often considered. If monomeric prolactin is clearly elevated or you have significant symptoms, your clinician may recommend earlier follow-up and additional labs rather than waiting.