What is analysed?
Prolactin is a hormone, produced by the anterior pituitary gland, that stimulates lactation (breast milk production).
Prolactin levels are high during pregnancy and in the postpartum period. Concentrations will remain elevated as long as the mother continues breastfeeding, but will gradually fall back to pre-pregnancy levels afterwards.
Besides pregnancy, the other primary cause of high prolactin levels is a prolactinoma, a tumour of the pituitary gland.
What does the result mean?
The result indicates the concentration of prolactin in the bloodstream.
Why conduct the analysis?
The prolactin test is conducted to determined if prolactin levels are higher (or sometimes lower) than what is considered normal.
When to conduct the analysis?
The prolactin test may be conducted:
- When symptoms of elevated prolactin are observed, including galactorrhoea (spontaneous breast milk production outside of pregnancy), problems with vision, headaches.
- When investigating female and male infertility.
- When performing follow-ups for low testosterone in males.
What sample is required?
A blood sample is required. The blood is taken from a vein, usually in the arm.
Prolactin levels will fluctuate over a 24-hour cycle. Preferably, the blood sample should thus be taken a few hours after waking up, following a period of relaxation of 30 minutes. In some cases, however, the healthcare professional may have specific reasons for performing a blood sample at another time.
Is any prior preparation necessary?
No prior preparation is necessary.
How is it performed?
The sample is sent to a laboratory, where it is analysed using immunoassays techniques to detect and quantify prolactin concentrations.
What are the normal values?
Normal reference ranges for prolactin vary by sex, as shown in the table below.
What does having altered values mean?
- High prolactin levels: Indicate conditions such as prolactinoma (pituitary tumour), hypothyroidism, or medication side effects.
- Low prolactin levels: Indicate conditions affecting the pituitary gland's function.