What Causes High Prolactin Levels in Non Pregnant Females?

What Is Prolactin?

Prolactin is a hormone secreted by the anterior portion of the pituitary gland. At the cellular level, prolactin helps in cell growth, maturation, differentiation, and also survival.

In a normal, healthy human being, prolactin is responsible for carrying out as well as regulating the following functions;

1. Reproduction and reproductive cycles in females
2. Immunity
3. Regulation of water and electrolyte balance
4. Adaptation to stressful situations
5. Regulation of metabolic functions
6. Regulation of functions of the skin
7. Behavior and psychological state

It is also assumed that prolactin levels in females majorly influence behavioral and psychological states during pregnancy, lactation, and also during menstrual cycles.

What Are High Prolactin Levels?

Before understanding more about high prolactin levels in non-pregnant females, we need to know what the normal reference range is.

Any increase in prolactin levels beyond the normal range is considered to be abnormal especially among men and non-pregnant women.

High prolactin levels or hyperprolactinemia affects about 0.4% of the total population worldwide, being more common among women than in men. According to studies, about 3-10% of women with polycystic ovarian syndrome (PCOS) have co-existent hyperprolactinemia.

During pregnancy, serum prolactin levels increase throughout pregnancy and reduce gradually as soon as labor begins. Following labor, serum prolactin levels vary depending on whether breastfeeding is done or not.

What Causes High Prolactin Levels In Non-Pregnant Females?

High prolactin levels during pregnancy are a common occurrence since the prolactin hormone plays an essential role in the maintenance of pregnancy. However, high prolactin levels in non-pregnant females are unusual and require evaluation and treatment.

High prolactin levels may exhibit certain signs and symptoms related to the underlying cause or may be completely asymptomatic.

Under normal conditions, prolactin levels may increase during sleep and may also be seen as a result of excessive stressful situations – both mental and physical.

Some clinical conditions resulting in high prolactin levels in non-pregnant females are;

1. Idiopathic hyper-prolactinemia – Meaning no known cause (about 40% cases)
2. Tumors of the hypothalamus or the pituitary gland leading to excessive abnormal secretion of prolactin
3. Damage to the hypothalamus or pituitary gland due to injury, radiation, or surgical damage
4. Infections such as tuberculosis
5. Cushing’s syndrome
6. Addison’s disease
7. Major systemic disorders such as;
   • Chronic renal failure
   • Hypothyroidism
   • Cirrhosis of liver
   • Epilepsy or seizure disorder
8. Drug-induced hyper– Secretion of prolactin, due to medications such as:
   • Phenothiazines
   • Benzamides
   • Alpha-methyldopa, opiates
   • Ranitidine
   • Amphetamines and hallucinogens
   • Estrogens and anti-androgens
   • Calcium channel blockers

Signs And Symptoms Of High Prolactin Levels In Non-Pregnant Females

High prolactin levels may present with signs and symptoms depending upon age, gender, and severity of illness responsible for causing hyperprolactinemia. Clinical presentation is more apparent and appears sooner in women than in men.

Women with high prolactin levels may present with;

• Oligomenorrhoea or scanty menses
• Amenorrhea or absence of menstrual flow
• Galactorrhoea or abnormal milk discharge
• Decreased libido
• Infertility
• The decrease in bone mass

Males affected with high prolactin levels may present with erectile dysfunction, infertility, reduced bone mass, and reduced libido.

How To Test High Prolactin Levels?

Prolactin levels can be known with the help of a simple blood test. Testing for serum prolactin levels requires overnight fasting, that is, about 10-12 hours of fasting before collection of blood samples. A sample of blood is collected and tested in the laboratory for the same.

However, some precautions need to be exercised because serum prolactin levels show a diurnal variation, which means that prolactin levels may vary at different times of the day. Due to these variations, test time must be carefully selected to get accurate results.

Prolactin levels are higher in the afternoon than in the morning. Therefore blood samples must be preferably collected in the morning.

A repeated test may be advised if the value is found high in order to arrive at a definitive diagnosis. Markedly raised levels of prolactin do not require re-testing.

Medications that may cause high prolactin levels must be stopped for about 48-72 hours if it is safe to do so and prolactin levels must be repeated again.

The following factors must be excluded before diagnosing a female with hyperprolactinemia;

• Non-fasting sample
• History of using medications which may cause hyperprolactinemia
• Excess exercise
• Recent history of chest wall surgery or injury
• Renal disorders
• Liver cirrhosis
• History of seizure 1-2 hours prior to testing

If prolactin levels are found to be high, further imaging studies such as a CT scan or an MRI scan may be required to rule out the presence of tumors of the pituitary gland or the hypothalamus.

Treatment For High Prolactin Levels

Nearly 40% of patients with hypothyroidism have mildly elevated prolactin levels and therefore thyroid hormone replacement normalizes prolactin levels in these patients.

Medical management of high prolactin levels in a non-pregnant female can be considered under the following points;

• Medical management of hyperprolactinemia is suggested for a period of about 8 months to two years, depending upon patients’ response to treatment.
• In the case of tumors that show very slow growth or no expansion along with the absence of signs and symptoms, do not require any treatment.
• Hormone replacement therapy (HRT) is started for all females who complain of amenorrhea (absence of menses) in order to replenish estrogen deficiency
• Dopamine antagonists like bromocriptine and cabergoline have been drugs of choice for prolactinomas for several years.
  However, these drugs are associated with side effects like headache, dizziness, nausea, vomiting, constipation, and nasal stuffiness. Neuro-psychological side effects include depression, auditory and visual hallucinations, mood swings, and delusions.
• An alternative to oral administration of these drugs is vaginal usage. This route of administration shows better tolerance to these drugs.
• Trans-nasal transsphenoidal microsurgical excision is advised for larger tumors. However, this surgery is associated with long term hypopituitarism (inadequate or absence of secretion of pituitary gland hormones). Patients may also show a relapse of hyper-prolctinemia.
• External radiation therapy is advised to patients in whom the tumors are not removed completely.

High prolactin levels in non-pregnant females must not be neglected as it indicates the presence of a more serious underlying disorder that needs to be addressed and treated timely. Also, prolactin levels play a great role in regulating reproductive cycles and reproduction, which is very crucial for every female.