**2. Clinical diagnosis of hyperprolactinemia**

148 Prolactin

(Baird 1979)

depression of pituitary FSH secretion (Marrs 1981).

half of pregnancy in rodents. (Binart 2000)

clinics (Crosignani 1999)

Menstruation and ovulation may only occasionally occur before the drop of elevated basal PRL levels. As time goes on with less frequent breastfeeding, e.g. during weaning however, the PRL levels do not stay as high and the woman may start to ovulate. In cases of nonlactating/ nonbreastfeeding mothers, that may happen between 2-3 month after delivery.

Similarly, elevated PRL levels are shown during gestation, but mechanisms to inhibit ovulation is related to elevated estardiol and progesterone levels and a consequent

Generally, the lactogenic hormones play role also in regulation of reproductive function. On one hand, PRL is essential to maintain regular oestrus cycles. PRL knock out mice are completely infertile (Horsemann 1997). One of the other actions of PRL is to stimulate ovarian production of progesterone. That is required in the process of preparation for embryo implantation and it is dependent on a continued estrogen and progesterone secretion by the corpus luteum, which is supported by a functional pituitary during the first

On the other hand, high prolactin levels are associated with anovulation or may cause directly or indirectly infertility. In young women, hyperprolactinemia is probably one of the most common endocrine disorders related to pituitary function. Women who are not pregnant and are not breastfeeding should have lower levels of basal PRL (typically 10–28 μg/L in women and 5–10 μg/L in men are defined as "normal levels") If a non-pregnant woman has abnormally high levels of PRL, it may cause her difficulty in becoming pregnant. It is considered as the most frequent cause of anovulatory sterility, although spontaneous pregnancy may occur occasionally. The prevalence of hyperprolactinemia varies in different patient populations, stays below 1% (0.4% in an unselected normal population) but can be as high as 17% of women with reproductive disorders shown at the

The suppression of pituitary hormones by PRL, similar that described during lactation has an indirect anovulatory effect. PRL however, acts also directly on the ovary to inhibit the hCG-induced follicle rupture, resulting in the inhibition of ovulation. (Yoshimura 1989).

Clinically significant elevation of PRL levels may cause infertility in several different ways. First, prolactin may stop a woman from ovulating. If this occurs, a woman's menstrual cycles will stop. In less severe cases, high prolactin levels may only disrupt ovulation once in a while. This would result in intermittent ovulation or ovulation that takes a long time to occur. Women in this category may experience infrequent or irregular periods. Women with the mildest cases involving high prolactin levels may ovulate regularly but not produce enough of the hormone progesterone after ovulation. This is known as a luteal phase defect. Deficiency in the amount of progesterone produced after ovulation may result in a uterine lining that is less able to have an embryo implant. Some women with this problem may see

their period come a short time after ovulation (Shibli-Rahhal,2011)

A variety of etiological factors including disorders of the hypothalamo-pituitary axis, interruption of dopamine synthesis, stress, pituitary tumours, polycystic ovary syndrome, primary hypothyroidism, and various medications may lead to hyperprolactinemia (5). Hyperprolactinemia in girls causes delayed puberty, hypogonadotropic hypogonadism, primary or secondary amenorrhea, and galactorrhea (Fideleff, 2000). Hyperprolactinemia in men may result in as a first signs of decreased libido or impotence, however also cause inefficient sperm production and infertility (Colao, 2004).

As one of the fist signs in women with high prolactin levels may have irregular periods or no periods at all. Another common symptom is "galactorrhea", which is the occurrence of a milky discharge from the breast in a woman who has not recently been pregnant. The

discharge is the result of persistant high PRL levels stimulating the mammary gland for milk production. Some women may see galactorrhea occur spontaneously. Others may see it only if they squeeze their nipples.

Prolactin and Infertility 151

hyperprolactinemia, but it has minimal bioactivity in vivo and is not of pathological significance. As necessary the reference technique of gel filtration chromatography at the laboratory should be available for confirmation and request on investigation of samples to

Pituitary adenomas are the most common tumour type in the pituitary gland. There is approximately 10% incidence was shown obtained by post-mortem autopsy, with similar ratio of male and female patients. The most frequently detected tumours (over 39%) are sparsely granulated PRL cell adenomas. The others types are GH cell or mixed PRL/GH adenoma, ACTH cell adenoma/Crooke's cell adenoma (~14%) ; Gonadotroph cell adenoma (6.6%); Null cell adenoma/oncocytoma (~32%) and other or unclassified types (Buurman,

Invasive tumours with multiple recurrences are only classified as aggressive tumours or "atypical adenomas". Tumours with systemic metastasis must be considered as carcinomas, and "only" make up 0.1% to 0.2% of all pituitary tumours, but with very poor prognostics of 66% mortality (Oh, 2012). However it was suggested that a full picture inlcuded clinical signs (gender, DA-resistant hyperprolactinemia, etc) , radiological status (invasive macro or giant tumour) and histological signs of angiogenesis, mitoses level, vascular invasion and molcular biology parameters (Ki-67 > 3 %, p53 positive, up-regulation of genes related to invasion and proliferation, and allelic loss of chromosome 11) should be taken into account considering the potential malignancy, prognosis of prolactin secreting tumours and identify the optimal therapy as early as possible. The key question is to identify factors associated with tumour aggressiveness. The approach combined genomic and transcriptomic analysis focus to the subtype of pituitary tumour able to identify molecular events associated with the aggressive and malignant phenotypes. Allelic loss in certain loci of chromosome 11 has been detected in tumours with signs of malignancy, potentially responsible for triggering the aggressive and malignant phenotypes. Within the recent years there are an increasing number of genes or molecular signs that has been associated with pituitary tumorigenesis to develop predictive and potential prognostic markers. (Zemmoura, 2012; Dworakowska,

About one-third of all pituitary tumours are not associated with hypersecretory syndromes but, rather, present with symptoms of an intracranial mass, such as headaches, nausea, vomiting or visual field disturbances. Only rare cases of pituitary tumours are considered as malignant prolactinoma. Tumours that produce growth hormone (GH) may also secrete prolactin in nearly 25% of cases. This is a common source of misdiagnosis, as the features of prolactin excess may capture attention while the more subtle features of GH excess go

avoid confusion of diagnostics. (Fahie-Wilson 2005)

**4. Causes of high prolactin levels** 

**4.1. Pituitary tumours** 

2012; Wierinckx 2011)

unnoticed.

2006).

As diagnostic practice, after signs and labtests have been evaluated the magnetic resonance imaging (MRI) of the pituitary gland should be performed in all patients. A pituitary adenoma with a diameter of less than 1 cm is defined as "microadenoma" and one above 1 cm in diameter as "macroadenoma".

#### **3. Measurement of prolactin**

Prolactin can be measured with a simple blood test drawn at the fertility doctor's office. In order to get accurate results, prolactin should be drawn first thing in the morning. Since PRL may serve as a hormone to affect reproductive functions, sexual contact, stimulation of nipples in human may cause a not just immediate but also next-day-long alterations of the PRL secretory pattern. (Kruger 2012) These fluctuations are measured on the next day to produce a PRL elevation around noon, additional of the regular circadian rhythm of PRL levels, as the peak on the morning. Accordingly it is important to note that the woman should have the instructions to eat nothing from the night before and to avoid any stimulation of the breast and nipples, included sexual intercourse as well, from the day before also.

Since stimulation of the breast /nipples (stress such as physical exam) may cause immediate release of PRL one common mistake that doctors make is to draw a prolactin blood test immediately after a patient has had a breast exam in the office. These women will have high prolactin levels because of the exam and therefore they may show false (i.e. transient) increase of PRL levels. Prolactin should also be drawn early in the menstrual cycle - before ovulation. This is because prolactin levels are naturally higher after ovulation.

A prolactin level of 5-20 ng/mL is considered normal in both sexes, according to some laboratories and test references the male and female (a bit higher) normal range may differ. A level above 20 ng/mL in two successive measurements is defined as hyperprolactinemia (7). According to WHO standards: 1 μg/L = 21.2 mIU/L. PRL levels > 250 ng/mL usually indication for prolactinoma, when PRL > 500 ng/mL it is considered as diagnosis for macroprolactinoma. (Melmed, 2011)

There are cases when false positive and elevated PRL levels are measured: two high molecular mass forms of prolactin (PRL) in serum have been identified: macroprolactin (bigbig PRL, > 100 kDa) and big PRL (40-60 kDa). Big PRL is a consistent "normal" component of total serum PRL but rarely cause of hyperprolactinemia. Macroprolactin is usually a complex of PRL and IgG in composition, it is formed in the circulation from monomeric PRL with a molecular mass of 150-170 kDa, but may have some additional variability in composition. In labor tests the PRL in the complex remains reactive to a variable extent in immunoassays. Individuals may show a different pattern of % of these variants, or even can be a predominant immunoreactive component of circulating PRL and the cause of apparent hyperprolactinemia, but it has minimal bioactivity in vivo and is not of pathological significance. As necessary the reference technique of gel filtration chromatography at the laboratory should be available for confirmation and request on investigation of samples to avoid confusion of diagnostics. (Fahie-Wilson 2005)
