Prolactin Hormone Test (B-209)
Explore a Hormonal Cause of Irregular Periods, Fertility Difficulties and Low Libido
Changes in prolactin can affect reproductive health in both women and men. Elevated levels may interfere with ovulation, menstrual cycles and testosterone production — contributing to symptoms that can otherwise be difficult to explain.
The Prolactin Hormone Test (B-209) measures your prolactin level using a simple at-home finger-prick dried blood spot sample.
Whether you are investigating irregular periods, unexpected breast milk production, difficulty conceiving or symptoms associated with low testosterone, this focused test provides useful information for deciding what to investigate next.
| Test Information | Details |
|---|---|
| Test ID | B-209 |
| Biomarker measured | Prolactin |
| Sample type | Dried Blood Spot (DBS) |
| Test method | ECLIA — electrochemiluminescence immunoassay |
| Suitable for | Adult women and men |
| Collection location | At home — no clinic visit required |
| Laboratory | ZRT Laboratory — CLIA-certified |
| Results | Usually 3–5 working days after laboratory receipt |
| Report | Prolactin result, applicable reference range and specialist laboratory commentary |
What This Test Measures
Prolactin is a hormone produced by the pituitary gland, a small gland at the base of the brain.
It is best known for supporting breast milk production after childbirth. Outside pregnancy and breastfeeding, persistently elevated prolactin can disrupt the signals involved in normal reproductive function.
In women, this can interfere with ovulation and menstrual regularity. In men, it can suppress reproductive hormone signalling and contribute to reduced testosterone and sexual symptoms.
B-209 measures prolactin only. It does not include testosterone, oestradiol, progesterone, LH, FSH or thyroid hormones.
For Women: Investigate Menstrual Changes and Ovulation Concerns
Who Should Consider This Test?
Prolactin testing may be useful if you have:
- Irregular, infrequent or absent periods.
- Difficulty conceiving, particularly alongside menstrual changes.
- Unexpected breast milk production when not pregnant or breastfeeding.
- Low libido or vaginal dryness alongside other reproductive symptoms.
- Concerns about ovulation.
- A previous elevated prolactin result requiring practitioner-led follow-up.
- A recommendation to check prolactin during a fertility assessment.
How Can This Test Help?
| Your Concern | How Prolactin Testing Can Help |
|---|---|
| Irregular or absent periods | Identifies whether elevated prolactin may be disrupting reproductive hormone signalling. |
| Difficulty conceiving | Helps investigate a hormonal factor that can interfere with ovulation. |
| Unexpected breast milk production | Checks whether the symptom is accompanied by elevated prolactin. |
| Low libido or vaginal dryness | Adds information when assessing possible suppression of ovarian hormone activity. |
| Possible thyroid-related menstrual changes | An elevated result may prompt thyroid assessment, as an underactive thyroid can raise prolactin. |
Why Prolactin Matters for Ovulation
Excess prolactin can suppress the hormonal messages that regulate LH and FSH. This can interfere with follicle development, ovulation and ovarian sex hormone production.
Measuring prolactin helps establish whether this pathway deserves attention as part of your fertility or menstrual health assessment.
For Men: Explore Hormonal Factors Affecting Testosterone and Sexual Wellbeing
Who Should Consider This Test?
Prolactin testing may be useful if you have:
- Low libido or erectile difficulties.
- Low testosterone, particularly when the cause is unclear.
- Fertility difficulties alongside signs of a hormonal problem.
- Unexpected breast milk production or breast-related symptoms.
- A previous elevated prolactin result.
- A practitioner’s recommendation to investigate pituitary hormone activity.
How Can This Test Help?
| Your Concern | How Prolactin Testing Can Help |
|---|---|
| Low testosterone | Checks for elevated prolactin as a possible contributor to suppressed reproductive signalling. |
| Low libido or erectile difficulties | Adds a relevant hormone measurement to the wider assessment of sexual symptoms. |
| Difficulty conceiving | Helps investigate a hormonal factor that may affect testosterone and reproductive function. |
| Unexpected breast milk production | Establishes whether prolactin is elevated and supports further investigation. |
Why Prolactin Matters for Testosterone
Elevated prolactin can reduce the hormonal stimulation needed for normal testosterone production.
This test does not measure testosterone or sperm quality. Depending on your symptoms, your practitioner may recommend testosterone, LH and FSH measurements or a semen analysis alongside prolactin testing.
Understanding Your Prolactin Result
Higher Prolactin
A raised result is called hyperprolactinaemia. Possible causes include:
| Possible Cause | Why It Matters |
|---|---|
| Pregnancy or breastfeeding | Prolactin rises naturally to support milk production. |
| Medicines | Some medicines, including certain mental health treatments, can increase prolactin. |
| Underactive thyroid | Thyroid dysfunction can stimulate increased prolactin production. |
| Prolactinoma | A benign, non-cancerous pituitary growth can produce excess prolactin. |
| Kidney or liver dysfunction | These conditions can affect circulating prolactin levels. |
| Temporary physiological influences | Stress and other short-term influences can contribute to an elevated measurement. |
An elevated result does not automatically mean a pituitary growth is present. Your practitioner may recommend repeat testing, medication review, thyroid testing or another investigation to establish the cause.
Lower Prolactin
Lower prolactin usually has limited significance in routine fertility assessment. In some circumstances, it may reflect reduced pituitary function.
Interpretation depends on your symptoms, medication use and other hormone results.
Prolactin Within the Reference Range
A result within the applicable range makes persistent prolactin excess less likely as an explanation for your symptoms. Your practitioner can then consider other relevant hormonal or non-hormonal factors.
Prolactin Reference Ranges
Your report will show your prolactin result alongside the laboratory’s applicable reference range.
Pregnancy, breastfeeding, medication use and clinical circumstances affect interpretation. Record these details accurately on your requisition form.
The supplied fertility PDFs do not provide numerical prolactin reference ranges, so the range on your individual laboratory report should be used.
When Should You Collect Your Sample?
Women With Regular Periods
The laboratory’s fertility guide highlights early follicular collection — Days 2–4 — as useful for assessing prolactin with less oestrogen influence.
- Count Day 1 as the first day of full menstrual bleeding, not spotting.
- Follow the kit’s instruction to collect while menstrual flow continues.
- If your bleeding is short, collect on Day 2.
If your practitioner requests another collection day, follow their guidance.
Women Having Luteal-Phase Testing
The fertility kit also provides a luteal-phase collection option:
| Usual Cycle Length | Collection Window |
|---|---|
| 23–26 days | Day 17, 18 or 19 |
| 27–30 days | Day 21, 22 or 23 |
| 31–34 days | Day 25, 26 or 27 |
| Longer or shorter cycles | Approximately 5–7 days before the next expected period |
For prolactin-only testing, luteal collection does not confirm ovulation. Use the collection timing recommended for your assessment.
Women With Irregular or Infrequent Periods
The laboratory permits collection on any non-bleeding day when cycles are unpredictable or infrequent.
If you do not menstruate, ask your practitioner to confirm a suitable collection day rather than waiting for a period.
Men
Men can collect on any day of the month, following the kit instructions and any treatment-specific guidance.
Time of Day
The supplied fertility kit instructions advise collecting your blood spot sample within one hour of waking.
If your practitioner requests a repeat prolactin measurement under different conditions, follow the instructions given for that repeat test.
Benefits of the Prolactin Hormone Test
- Focused testing of a hormone relevant to reproductive and sexual health.
- Suitable for women and men.
- Convenient at-home finger-prick collection.
- ECLIA laboratory analysis.
- Specialist commentary to support interpretation.
- Useful next-step information for investigating menstrual changes, fertility concerns and low testosterone.
- Laboratory fee included in the purchase price.
How It Works
- Order your kit — receive the collection materials and instructions at home.
- Choose your collection day — follow the relevant guidance for your circumstances.
- Collect your sample — complete the finger-prick dried blood spot collection.
- Post your sample — return the dried card and completed paperwork to ZRT Laboratory.
- Receive your report by email — usually within 3–5 working days of the laboratory receiving a suitable sample and completed paperwork.
What You Receive
- An at-home dried blood spot collection kit.
- Laboratory measurement of prolactin.
- Your result with the applicable reference range.
- Specialist laboratory interpretation.
- Information to support a discussion about further assessment.
- Laboratory testing included in your purchase.
Customers are responsible for the cost of posting their sample to the laboratory.
Why We Use ZRT Laboratory
ZRT Laboratory is a CLIA-certified diagnostic laboratory based in the USA, specialising in hormone and wellness testing.
Prolactin is available through its dried blood spot testing service both as an individual measurement and within the Fertility Basic and Fertility Advanced panels.
For B-209, prolactin is measured using electrochemiluminescence immunoassay technology.
Prolactin Only or a Broader Hormone Panel?
| Test | Biomarkers Included | Main Focus |
|---|---|---|
| B-209 — Prolactin | Prolactin only | Focused investigation of prolactin levels |
| B-204 — LH/FSH | LH and FSH | Reproductive hormone signalling |
| B-244 — Fertility Basic | AMH, LH, FSH, TSH, prolactin and cortisol | Broader female fertility hormone assessment |
| B-245 — Fertility Advanced | Basic markers plus oestradiol, progesterone, testosterone and DHEAS | Expanded female reproductive hormone assessment |
Choose B-209 when you specifically need a prolactin measurement. A broader assessment may be more useful when several hormonal explanations need investigating.
B-209 Prolactin Test — Sample Collection Instructions
Sample type: Dried Blood Spot
View the Full Fertility Sample Collection Instructions
Read the instructions supplied with your kit before collection.
1. Choose Your Collection Day
Follow the collection guidance above or the timing requested by your practitioner.
Plan to collect within one hour of waking, as directed in the fertility kit.
2. Record Medicines and Hormone Treatments
List all medicines, supplements and hormones on the requisition form. Include pregnancy or breastfeeding status where applicable.
Medication information is particularly important for prolactin interpretation. Do not stop prescribed medicines to change your result.
The laboratory’s fertility kit instructions do not recommend testing for users of hormonal contraceptive pills, patches, vaginal rings, injections or implants. Testing is permitted with a progestin IUD; record its use.
If prolactin testing has been requested while you use contraception, confirm the collection plan with your practitioner.
3. Prepare Three Days Before Collection
Follow the laboratory’s instructions to avoid:
- Biotin / vitamin B7 supplements, including hair and nail formulas.
- Anti-ageing or anti-wrinkle facial creams.
If biotin is prescribed, ask your prescriber before withholding it.
4. Follow Hormone-Treatment Guidance
Continue prescribed treatment and follow the treatment-specific instructions supplied with the kit.
| Treatment Type | Laboratory Guidance |
|---|---|
| Topical, swallowed, troche or sublingual hormones | The instructions advise allowing at least 12 hours between an evening dose and morning collection. Oral progesterone may be taken at bedtime. |
| Topical hormones | Use gloves or an applicator for at least two days before collection. Avoid applying hormones to the face, lips or neck. |
| Non-contraceptive patches, rings, pellets or injections | Follow the laboratory’s midway-between-doses guidance; ask your prescriber where the treatment has no clear dosing interval. |
| Hydrocortisone, prednisone or other glucocorticoids | Ask your practitioner about collection timing. |
For topical hormone users, the laboratory also advises changing sheets, pillowcases and towels the night before collection and avoiding surfaces containing hormone residue.
5. Prepare Your Card and Hands
- Stay well hydrated without excessive fluid intake.
- Label the card with your name, collection date and time.
- Wash your hands with soap and warm water.
- Dry them with a clean towel.
- Warm your hands to encourage circulation.
- Open the card without touching the filter paper.
6. Collect the Blood Spots
- Place the card on a clean, flat surface below waist level.
- Select the middle or ring finger of your non-dominant hand.
- Clean the finger with the alcohol pad and allow it to air dry.
- Use the lancet as instructed.
- Wipe away the first blood drop with sterile gauze.
- Keep your hand below your waist and gently encourage blood flow without excessive squeezing.
- Allow one large drop to fall onto the centre of each circle.
- Apply a dressing when finished.
Each spot should fill as much of the circle as possible and soak through to the back.
Do not layer drops, smear blood or touch the collection paper. Several well-formed spots are preferable to many small or poor-quality spots.
7. Dry the Card
Leave the card open to air dry for at least four hours.
Once completely dry, close the cover. Keep it in a cool, dry place away from direct sunlight until shipment.
8. Complete the Paperwork and Post
Place the fully dried card and completed requisition form inside the kit box. Close it securely and use the supplied return packaging and instructions.
Post promptly.
If shipping is delayed beyond 24 hours, freeze the dried sample inside its sample bag, as directed by the laboratory. Samples must reach the laboratory within 30 days of collection to avoid rejection.
The laboratory analysis fee is included in your purchase. Return postage is your responsibility.
Frequently Asked Questions
Can Both Women and Men Use This Test?
Yes. Prolactin can affect reproductive hormone signalling in both sexes. Testing can contribute to the investigation of menstrual changes, fertility difficulties, low testosterone and sexual symptoms.
Can High Prolactin Affect Fertility?
Yes. Persistently elevated prolactin can interfere with the hormonal signals involved in ovulation and testosterone production.
Does High Prolactin Mean I Have a Pituitary Tumour?
No. Medicines, pregnancy, breastfeeding, thyroid dysfunction and other factors can also raise prolactin. Further assessment establishes the cause.
Can Medicines Affect My Result?
Yes. Some medicines can increase prolactin. Record all treatments on your form and continue prescribed medication unless your prescriber advises otherwise.
Can I Test During Pregnancy or Breastfeeding?
Prolactin rises naturally during pregnancy and breastfeeding. A routine result cannot be interpreted in the same way as a non-pregnant, non-breastfeeding result. Testing in these circumstances should follow a practitioner’s recommendation.
Does This Test Measure Testosterone or Thyroid Function?
No. It measures prolactin only. Testosterone or thyroid testing may be recommended depending on your symptoms and result.
What Happens if My Prolactin Is Elevated?
Your practitioner may recommend a repeat measurement, review of medicines, thyroid testing or other investigations. The next step depends on the degree of elevation and your symptoms.
Does the Price Include Laboratory Testing?
Yes. The laboratory fee is included. You pay the cost of posting your sample to the laboratory.
Take a clearer next step in understanding your reproductive and hormonal health with convenient at-home prolactin testing.