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Serum Prolactin Level (Post-Radiotherapy)

Published: August 9, 2026Updated: August 16, 2026

This test measures the amount of prolactin, a hormone produced by your pituitary gland, in your blood after you’ve received radiotherapy treatment. It helps doctors monitor how your body responds to the therapy.

Quick summary

Prolactin levels may be checked to assess treatment effects or side effects related to radiotherapy.

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
44931-4
Short code
Prolactin pre TRH IV SerPl-aCnc
Synonyms
Prolactin pre TRH IV SerPl-aCnc
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
2
Ref high
18
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
84146
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

Why This Test Is Done

Your healthcare provider may order this test if you’ve been treated with radiotherapy for conditions like breast cancer, pituitary tumors, or other conditions affecting hormone production. It can help track whether the treatment is working or if hormonal imbalances are developing.

What to Expect Before the Test

No special preparation is needed, but you may be asked to fast for 8–12 hours before the blood draw if instructed. Bring your medical records or recent test results to your appointment.

What Happens During the Test

A healthcare professional will insert a needle into a vein in your arm or hand to collect a blood sample. You may feel a brief pinch, but it usually doesn’t cause significant discomfort. The blood is then sent to a lab for analysis.

What the Results Mean

Results are compared to standard reference ranges, but individual needs vary. High prolactin levels may indicate overproduction, while low levels could signal underproduction or treatment-related effects. Your doctor will discuss findings in the context of your overall health and treatment plan.

Reference range

Adult males: 2-18 ng/mL; Females: 2-29 ng/mLN/A

Specimen: serum

For females: inform if menstrual cycle status. For certain tests, timing within menstrual cycle may matter.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

Prolactin (Post-Therapy)

Frequently asked questions

What causes elevated prolactin levels?
Elevated prolactin can result from radiotherapy affecting the pituitary gland, certain medications (e.g., antipsychotics), thyroid issues, or tumors. It may also signal potential side effects of treatment that need monitoring.
How often should this test be repeated?
Frequency depends on your treatment plan. Your doctor may recommend follow-up tests every few months or as needed to adjust therapy or address concerns about hormonal balance.
Can lifestyle changes affect prolactin levels?
Yes, stress, certain medications, and hormonal imbalances (e.g., thyroid dysfunction) can influence prolactin. Avoiding smoking, managing stress, and discussing medications with your provider may help stabilize levels.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy