Prolactin, Serum/Plasma


Prolactin is a polypeptide hormone synthesised in and secreted from specialised cells of the anterior pituitary gland, the lactotrophs, as well as other organs and tissues. Besides its role in the maturation of mammary glands and lactation, prolactin has over 300 separate biological activities. Biological actions of prolactin include lactation, luteal function, reproductive behaviour (female receptivity & parental behaviour), and homeostasis (immune response, osmoregulation, and angiogenesis). In humans, plasma concentrations of prolactin are the highest during sleep and the lowest during the waking hours. The best-known physiological stimulus affecting prolactin secretion is the suckling stimulus. Pre-ovulatory surge of prolactin secretion occurs, which is similar in timing to that of LH. In addition, prolactin levels increase during pregnancy. Prolactin secretion isalso affected by variations of day length. Audition, olfaction, and
stress can also influence prolactin secretion.


Prolactinomas, the most common hormone-secreting pituitary adenomas, are associated with hyper-prolactinemia. In hyperprolactinemic women, microadenomas predominate; these patients present with amenorrhea, infertility, and galactorrhea. Men usually have macroadenomas with higher prolactin levels and present with impotence, loss of libido, or infertility. In addition, hyper-prolactinemia can result secondary to hypothyroidism.

Sample Type, Quantity & Conditions

1 ml Serum 1 ml Li-Heparin or K3-EDTA Plasma Stability: 14 Days at 2-8 °C 6 Months at -20 °C

Special Precautions

Avoid taking sample after mammary or pelvic examination. Freeze only once.

Normal Range

Male: 4.04-15.2 ng/mL 86-324 µIU/mL Female (not-pregnant): 4.79-23.3 ng/mL 102-496 µIU/mL

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