Macroprolactin Test

The Macroprolactin Test is designed for patients who have a raised prolactin level and need to know whether that result reflects a genuine hormonal excess or a harmless laboratory phenomenon. Prolactin is a hormone produced by the pituitary gland that stimulates breast milk production. In some people, a large proportion of circulating prolactin is bound to immunoglobulin molecules, forming a complex known as macroprolactin. This complex is too large to exert normal biological activity at the tissues, yet it is still detected when prolactin is measured. The result is a falsely elevated prolactin reading that can lead to unnecessary anxiety, repeat testing, and even inappropriate treatment.

This test is particularly valuable for people who have an elevated prolactin result but no typical symptoms of true hyperprolactinaemia, such as galactorrhoea, menstrual disturbance, loss of libido, or infertility. It is also useful for those who have been labelled as having idiopathic hyperprolactinaemia and want clarity before committing to long-term therapy. The test helps distinguish true prolactin excess from macroprolactinaemia, allowing you and your doctor to make informed decisions about further investigation or treatment.

What is measured
- Macroprolactin: the proportion of prolactin that is bound to immunoglobulin, reported as a percentage or ratio to help identify macroprolactinaemia.
- Total prolactin: the overall prolactin level, which provides the context for interpreting the macroprolactin result.

Why it matters
A raised prolactin result can cause significant worry and may trigger unnecessary scans or medication. By identifying macroprolactinaemia, this test can prevent misdiagnosis, reduce the need for repeated blood tests, and ensure that treatment is only given when it is truly needed. It provides clear, clinically actionable information that helps you and your doctor understand what is really happening with your prolactin levels.

Prolactin Assessment
- Macroprolactin
- Total prolactin

No special preparation required.

For blood tests, we recommend drinking plenty of water beforehand to ensure smooth sample collection. If you are taking any regular medication, continue to do so unless advised otherwise by your doctor.