Prolactin Test - Uses, Procedure, and Indications

What Is Prolactin?

Prolactin, also known as the lactogenic hormone, is produced and secreted by the pituitary gland. The primary role of this hormone is to help women produce milk after childbirth. It is also referred to as the “milk hormone” in everyday language because of its role in lactation. Apart from lactation, prolactin has almost three hundred roles in our body. These roles can be broadly divided into reproductive, metabolism, osmoregulation, immunoregulation, and behavioral functions. Prolactin is mainly produced in the pituitary gland, but it is also seen in humans' uterus, breasts, adipose tissues, brain, prostate, and skin. Dopamine, a hormone produced by the hypothalamus, is responsible for prolactin regulation in the body. The higher the amount of dopamine, the lesser prolactin will be released. Prolactin is essential for both men and women; however, its specific function in men is still not clear.

What Is the Prolactin Test?

The prolactin test is a laboratory test that measures the amount of prolactin present in the blood. Usually, an elevated prolactin level is seen during pregnancy and just after childbirth (during lactation). However, prolactin levels can increase in other conditions that can indicate some kind of medical condition like pituitary gland tumors, infertility in women, erectile dysfunction in men, etc.

Why Is the Prolactin Test Done?

Regular men and non-pregnant women have a tiny amount of prolactin present in their blood. If this level increases, it can be due to several reasons like:

• Prolactinoma: Prolactinoma is a benign pituitary gland tumor that causes over production of prolactin.

• Diseases Affecting the Hypothalamus: This part of the brain controls the pituitary gland, and any disorder in the hypothalamus may cause increased prolactin production.

• Anorexia: It is an eating disorder.

• Medications: Many drugs can cause increased prolactin levels, including antidepressants, antipsychotics, and antihypertensive drugs.

• Chest Injuries and Irritation: Chest injuries and anger can also cause an increase in the level of prolactin production, for example, scars, shingles, very tight undergarments, etc.

When Is Prolactin Test Done in Women?

A prolactin test may be advised for women for several reasons.

• Symptoms of Prolactinoma in Women:

1. Headaches.

2. Visual impairment.

3. Production and discharge of breast milk outside of pregnancy or childbirth.

4. Nipple discharge.

5. Acne.

6. Abnormal facial hair growth.

7. Discomfort during sexual intercourse.

Apart from prolactinoma, women’s prolactin levels are tested for other medical conditions like infertility, polycystic ovary syndrome, etc. The signs and symptoms of increased prolactin in the blood are different for women before and after menopause.

• Symptoms of Increased Prolactin for Women Before Menopause:

1. Irregular menstrual cycles.

2. Tenderness in the breasts.

3. Infertility.

4. Premature menopause.

• Symptoms of Increased Prolactin for Women After Menopause:

1. Unusual weight gain.

2. Fatigue.

3. Muscle pain.

4. Constipation.

5. Difficulty in tolerating cold temperatures.

When Is Prolactin Test Done in Men?

A prolactin test is generally advised for men when a case of prolactinoma is suspected. The symptoms of prolactinoma in men are:

1. Nipple discharge.

2. Breast enlargement.

3. Decreased sex drive.

4. Decrease in the growth of the body and facial hair.

5. Erectile dysfunction.

6. Headaches.

7. Visual impairment.

8. Fertility issues.

Apart from prolactinoma, men are also advised to take a prolactin test to investigate testicular dysfunction that causes erectile dysfunction and other problems related to the pituitary gland and the hypothalamus.

How Is the Prolactin Test Done?

Like any other blood test, a prolactin test is also carried out by taking a blood sample from the vein (done by a phlebotomist). Then the sample is sent to the laboratory for evaluation. Some medications that might influence the test results should be avoided before the test (after consulting the doctor).

What Are the Risks of Prolactin Test?

Prolactin tests usually have low risks and very few chances of complications. The patient might have slight bruising and pain at the vein puncture site. However, this pain and bruising subside on their own. In rare cases, the patient might get an inflamed vein. Continued and excessive bleeding may occur in patients who have bleeding and clotting disorders or who are on anticoagulant (blood thinners) drugs.

What Is the Normal Range of Prolactin?

The usual prolactin range in women and men is mentioned below:

• Women who are not pregnant- Less than 25 ng/dL.

• Women who are pregnant- 34 ng/dL to 386 ng/dL.

• Men- Less than 15 ng/dL.

What Does a High Level of Prolactin Mean?

A very high level of prolactin in the blood is known as hyperprolactinemia, and about ten percent of the total population is affected by it. High prolactin levels are physiologically normal during pregnancy and right after childbirth during nursing. But an otherwise increase in the level of prolactin is not considered standard. Prolactinoma, liver diseases, kidney diseases, anorexia, and hypothyroidism are the most common causes of abnormally high levels of prolactin. Certain drugs also cause an elevation in the prolactin level; these include antihypertensive, antidepressants, and antipsychotic drugs.

What Is the Treatment for High Prolactin Level?

Most cases of increased prolactin do not require any treatment, and they get regulated on their own. Also, the doctor may not recommend any drugs or therapies in case of a minimal elevation in prolactin level. Some of the common treatment measures are as follows:

• Dopamine antagonists like Bromocriptine are the most commonly used treatment for high prolactin levels.

• Cabergoline is a new drug used for high prolactin with lesser side effects.

• In the case of patients who do not respond to Dopamine antagonists, radiation therapy may be advised.

• In the case of prolactinoma, surgery may be done to remove the tumor.

Apart from these treatments, some simple steps can also be followed to reduce prolactin levels:

• Eating a healthy and balanced diet.

• Avoiding stress.

• Avoid high-intensity workouts.

• Not wearing clothes that might stimulate the nipples.

• Take vitamin B6 and vitamin E supplements.

What Does Low Level of Prolactin Mean?

A slightly low prolactin level may not be a matter of concern, but a deficient level may indicate pituitary insufficiency. This means your pituitary gland is not working correctly. Certain drugs can cause a low prolactin level, like Dopamine, Levodopa, Ergot alkaloid derivatives, etc.

What Is the Treatment of Low Prolactin Level?

In most cases, a low prolactin level does not require treatment. But in cases where the level is critically low and treatment is needed, the underlying cause is first diagnosed, and then accordingly, treatment is given.

How Is Prolactin Related to Infertility?

It has been reported that high prolactin levels can cause infertility in some cases. Prolactinoma can cause problems with the production of hormones in the pituitary gland and eventually lead to hypopituitarism. In men, it causes lower sex drive and erectile dysfunction, and in women, it causes irregular menstrual cycles and infertility. Hyperprolactinemia also interferes with estrogen and progesterone production, which, in turn, causes problems in egg formation and release in the ovaries. Hormone replacement therapies and other drugs can easily cure this condition.

Conclusion:

The prolactin test is an easy laboratory blood test to evaluate and investigate the amount of prolactin hormone present in the blood. The increase or decrease in the level of this hormone may occur due to several reasons (including tumors, diseases, and drugs). An increased or decreased level of prolactin is not a life-threatening condition, but it can cause several issues related to fertility. Prolactin test is carried out easily, and their accuracy depends on the laboratory. Some easy treatment modalities are available to treat high and low prolactin levels in the blood.