Pituitary hormones and raised prolactin

The pituitary gland is a small gland at the base of the brain that plays a central role in regulating many hormones in the body. Pituitary hormone abnormalities are uncommon, but mild changes, particularly raised prolactin, are sometimes found on routine blood tests.

This page explains how GPs interpret pituitary hormone results, common benign causes of raised prolactin, when repeat testing is appropriate, and when specialist referral is needed.

These articles are intended as educational sources, not diagnostic nor taking place of a proper medical assessment. If you need help, please book an appointment with one of our GP’s.

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What the pituitary gland does

The pituitary gland releases hormones that help control:

Thyroid function (via TSH)
Reproductive hormones (FSH and LH)
Prolactin
Cortisol regulation (via ACTH)
Growth hormone

Because pituitary hormones affect multiple systems, results are always interpreted in context, alongside symptoms and other blood tests.

What prolactin is and why it is measured

Prolactin is a hormone involved in breast development and milk production. Outside of pregnancy and breastfeeding, prolactin levels are usually low.

GPs may check prolactin when someone has:

Irregular or absent periods
Unexpected breast milk production
Fertility concerns
Sexual dysfunction
Headaches or visual symptoms alongside other abnormalities
An incidental abnormal result on broader hormone testing

Common benign causes of raised prolactin

A mildly raised prolactin level is far more likely to be benign than serious.

Common non-pathological causes include:

Stress or anxiety at the time of blood testing
Poor sleep
Recent exercise
Minor illness
Certain medications, including antidepressants, antipsychotics and anti-sickness drugs
Macroprolactin (a biologically inactive form)

For this reason, GPs often recommend repeat testing before any further investigation.

Pituitary conditions linked to raised prolactin

Prolactinoma

A prolactinoma is a benign pituitary tumour that produces excess prolactin. Most prolactinomas are small and slow-growing.

Possible features include:

Persistently raised prolactin levels
Menstrual disturbance or infertility
Reduced libido
Breast milk production unrelated to pregnancy
Headaches or visual changes in rare cases

Diagnosis and management are led by endocrinology specialists.

Other pituitary hormone abnormalities

Occasionally, blood tests suggest abnormalities in other pituitary hormones, such as TSH, ACTH or growth hormone.

GPs assess:

Whether results are borderline or clearly abnormal
Whether symptoms support a pituitary cause
Whether repeat testing is needed to confirm results

Isolated, mild abnormalities often resolve on repeat testing.

How pituitary hormone abnormalities are investigated

Initial steps in primary care usually include:

Repeat blood tests under controlled conditions
Reviewing medication history
Checking related hormone levels

Imaging, such as MRI of the pituitary, is not routinely arranged in primary care and is usually requested following specialist advice.

When referral to endocrinology is needed

Referral may be appropriate if:

Prolactin remains significantly raised on repeat testing
Multiple pituitary hormone abnormalities are present
Symptoms suggest pituitary compression, such as visual disturbance
Results are inconsistent with stress or medication effects

When to seek urgent medical help

Urgent assessment is needed if pituitary hormone abnormalities are accompanied by:

Sudden severe headache
Visual field loss
Collapse or confusion

These situations require same-day medical attention.

AccessGP work with blood tests to help you

When to speak to a GP

You should seek GP review if:

You have symptoms that could be linked to raised prolactin, such as reduced libido, erectile concerns, menstrual changes, fertility concerns, or unexpected breast milk production
A prolactin test has come back raised and you are unsure what it means
You are taking medication that can affect prolactin and want advice on whether it may be contributing
You have persistent headaches, new visual symptoms, or symptoms that are worsening
You have more than one abnormal hormone result, or ongoing symptoms despite normal initial tests

Early review allows intervention before complications develop.

How various conditions are managed by GPs at AccessGP

GP insight

Most abnormal pituitary hormone results do not indicate serious disease. A cautious, stepwise approach helps avoid unnecessary imaging, anxiety and over-diagnosis, while ensuring that the small number of people who need specialist care are identified promptly.