Prolactin

1. Allow serum samples to clot completely before centrifugation. Physically separate serum or plasma from contact with cells as soon as possible. (Follow blood collection tube manufacturer's recommendations for centrifugation).


2. Store samples tightly stoppered at room temperature (15 to 30⁰C) for no longer than eight hours.


3. If the assay will not be completed within eight hours, refrigerate the samples at 2 to 8°C.


4. If the assay will not be completed within 48 hours, or for shipment of samples, freeze at -20°C or colder. Thaw samples only once.


5. Frozen specimens can be stored up to six months before testing.

MALE:  2.0 -18.0 ng/mL

FEMALE:  

1. Premenopausal/Non-pregnant (< 50 years of age):   3.0 -30.0 ng/mL


2. Pregnant:  10.0 - 209.0 ng/mL


3. Postmenopausal (≥ 50 years of age):  2.0 -20.0 ng/mL

Stages of Puberty (Tanner Stages)

                                           Female                                                         Male         

Stage I                            3.6-12.0 ng/mL                                           ≤ 10.0 ng/mL

Stage II-III                       2.6-18.0 ng/mL                                           ≤  6.1 ng/mL

Stage IV-V                       3.2-20.0 ng/mL                                          2.8-11.0 ng/mL

he primary physiological function of Prolactin is to stimulate and maintain lactation in women. In normal females, serum Prolactin levels generally range from 3–30 ng/mL (µg/L) while normal male levels typically range from 2–18 ng/mL (µg/L). Normal Prolactin secretion varies with time which results in serum Prolactin levels 2–3 times higher at night than during the day. The biological half-life of Prolactin is approximately 20–50 minutes. Serum Prolactin levels during the menstrual cycle are variable and commonly exhibit slight elevations during the mid-cycle. Prolactin levels in normal individuals tend to rise in response to physiologic stimuli including: sleep, exercise, nipple stimulation, sexual intercourse, hypoglycemia, pregnancy, and surgical stress.

Prolactin is secreted by the anterior pituitary gland and is required for normal breast development and lactation in women. during pregnancy and postpartum lactation, serum prolactin can increase 10 to 20 fold. Elevated Prolactin levels may be detected during the eighth week of pregnancy with levels continuing to rise throughout gestation. In the absence of breast feeding, Prolactin levels return to normal within three weeks after birth. Exercise, stress, and sleep also cause transient increases in prolactin levels. Consistently elevated serum prolactin levels (> 30 ng/mL), in the absence of pregnancy and postpartum lactation, are indicative of hyperprolactinemia. Hypersecretion of prolactin can be  caused by prolactin secreting pituitary adenomas (prolactinomas),  functional and organic diseases of the hypothalamus, breast or chest wall stimulation, renal failure, hypothyroidism, or ectopic tumors. Abnormally high levels of Prolactin are often associated with galactorrhea, amenorrhea, and female infertility, impotence, infertility and hypogonadism in men, primary hypothyroidism, and pituitary tumors.

Prolactin levels are elevated post-partum and in newborns. Elevated levels of Prolactin may be observed in cases of primary hypothyroidism due to an increased secretion of Thyrotropin releasing hormone (stimulates PRL release) accompanied by decreased serum T4 levels and increased serum thyroid stimulating hormone concentrations. Hyperprolactinemia has also been associated with the inhibition of ovarian steroidgenesis, follicle maturation, and secretion of luteinizing hormone and follicle stimulating hormone. Prolactin deficiencies in normal individuals are rare.

Various drugs have been shown to either increase or decrease Prolactin Levels. Administration of L-dopa suppresses Prolactin secretion. Bromocriptine inhibits Prolactin secretion and has been used in the treatment of amenorrhea and galactorrhea due to hyper-prolactinemia. Administration of psychotropic drugs (phenothiozines), anti-hypertensive drugs (reserpine), and Thyrotropin releasing hormone tend to increase prolactin secretion. Estrogen therapy also tends to elevate serum prolactin levels.