What is prolactin?

Prolactin (PRL), also known as luteotropic hormone or luteotropin, is a protein that in humans is best known for its role in enabling mammals, usually females in the production of milk after childbirth. Prolactin is normally secreted from the pituitary gland in response to eating, mating, estrogen treatment, ovulation, and nursing. Prolactin is secreted in a pulsatile fashion in between these events. It also plays an essential role in our metabolism, regulation of the immune system, and the development of the pancreas. 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.

Prolactin secretion is controlled by prolactin-releasing and prolactin-inhibiting chemicals (factors) secreted by an area of the brain called the hypothalamus. Another hormone, thyroid-releasing hormone, or TRH, can also stimulate prolactin.

Why measure the level of prolactin?

The examination may be helpful in identifying the cause of galactorrhea, which is when there is abnormal milk secretion, oramenorrhea, which is the absence of menstruation, and to evaluate the function of the pituitary, for assistance in diagnosis of infertility in some patients.

Stress from illness, trauma, surgery, or even nervousness about a medical test can elevate prolactin levels. Drugs that may increase prolactin include phenothiazines, opiates, oral contraceptives, histamine antagonists, monoamine oxidase inhibitors (MAO inhibitors), estrogen, and antihistamines. Drugs that can decrease values include levodopa and dopamine.

The prolactin test is order for women, when they display symptoms of prolactinoma, which is a non-cancerous tumor (benign) on the pituitary gland that produces high levels of prolactin. Symptoms that are associated with prolactinoma are unexplained headaches, lactation not associated with child birth or nursing (galactorrhea) and visual impairment. It is also used in instances when a female is experiencing problems with infertility, or irregular menstrual periods and also helps to rule out problems associated with the pituitary gland or hypothalamus.

In men the test may be conducted if they display the symptoms of prolactinoma, which are unexplained headaches, reduced sex drive, visual impairment, infertility problems, to investigate testicular dysfunction, erectile dysfunction, and to rule out problems with pituitary glands or hypothalamus.

Standard of preparation

Sampling is usually done in the morning in the hospital. There are no special preparations needed for this test. The doctor will advise and recommend if you need to be fasting prior to the blood examination. You should inform your doctor of any medication you are taking prior to the exam, as some medical treatments may interfere with the blood results.

Is the examination painful or dangerous?

The examination is neither painful nor dangerous. The patient may feel a tingling sensation with the entrance of the needle in the arm when blood is being extracted for examination.

How is the exam performed?

The exam consists of a simple blood sample test.