Prolactin

PROLACTIN TESTING & BRAIN TUMOUR

Question 1. What is Prolactin?

Prolactin is a hormone is synthesised and secreted by anterior pituitary gland in the base of the brain. Small amounts are also produced in other tissues including the breast, the deciduas, parts of the central nervous system and the immune system.

Pituitary prolactin secretion is regulated by nerves originating in the hypothalamus, via secretion dopamine causing inhibition of prolactin secretion. Thyrotropin-releasing factor (hormone regulating thyroid hormones) has a stimulatory effect on prolactin release.

 Question 2. What is the role of Prolactin?

Prolactin has many effects including regulating lactation, orgasms, and stimulating proliferation of nerve cells.

It stimulates the mammary glands to produce milk (lactation): Increased serum concentrations of prolactin during pregnancy cause enlargement of the mammary glands of the breasts and increases the production of milk. In pregnancy, this milk ejection is inhibited due to high levels of progesterone.  It is only when the levels of this hormone fall after childbirth that milk ejection is possible.

Sometimes, newborn babies secrete a milky substance (witch’s Milk) from their nipples. This is caused by the foetus being affected by prolactin circulating in the mother just before birth, and usually stops soon after birth.

Prolactin provides the body with sexual gratification after sexual acts: The hormone counteracts the effect of dopamine, which is responsible for sexual arousal. This is thought to cause the sexual refractory period. The amount of prolactin can be an indicator for the amount of sexual satisfaction and relaxation. Unusually high amounts are suspected to be responsible for impotence and loss of libido (see prolactinoma). High prolactin decreases normal levels of sex hormones — gonadotropins, FSH and estrogen in women and testosterone in men.

 Question 3. When is Prolactin level measured?

Prolactin is measured in blood when your doctor suspect prolactin-producing tumour from the pituitary gland called Prolactinoma.

 Question 4. How do I know I may have prolactinoma?

Consider prolactinoma in the following:

Severe headache without any obvious cause

New Vision Impairment

Loss of sexual Desire

Infertility

Breast Milk Discharge (galactorrhoea)

Menstrual Disorders

Features of thyroid Problem (see thyroid testing)

 Question 5. How is Prolactin Measured?

Prolactin is measured from a simple blood sample. It is detected using specific antibody to capture levels in blood called enzyme linked immunoassay. Very high levels are associated with symptoms as above and suggestive of prolactinoma.

 Question 6. What if my report is abnormal?

You will be referred to your doctor for further advice and treatment. You can request to have referral for CT scanning from our resident doctors for confirmation.

 Question 7. What other tests are there for Prolactinoma? 

CT and or MRI is available for confirmation. In PNG, only CT facility is available. MRI testing can be arranged in Australia through your doctor.

 Question 8. What are the pitfalls of Blood tests?

As many factors can affect mild-moderate elevations of prolactin, your doctor should assist in interpretation of abnormal levels. For example, mild elevations are seen during stress, and with use of certain medications.