Prolactin is a hormone most often associated with breast development and lactation in females, but it has effects in males as well. General effects of prolactin include blood vessel constriction, smooth muscle proliferation, and immune stimulation.
Low levels can be seen with pituitary dysfunction, infection, autoimmune disorders, hemochromatosis, metabolic syndrome, and reproductive disorders. Elevated levels may be associated with pregnancy, endothelial dysfunction, hypertension, stress, exercise, PCOS, infertility, and reduced libido in men. Certain medications can increase or decrease prolactin.
Standard Range:
Male 2.0 - 18 ng/mL (45.55 - 382.98 mIU/L)
Female 3.0 - 30 ng/mL (63.83 - 638.3 mIU/L)
The ODX Range:
Male 2.0 - 10 ng/mL (45.55 - 212.77 mIU/L)
Female 3.0 - 10 ng/mL (63.83 - 212.77 mIU/L)
Low levels may be seen with pituitary destruction or pituitary apoplexy. Medications that can decrease prolactin include dopamine, levodopa, clonidine, and ergot alkaloid derivatives (Pagana 2021). Low prolactin can be seen with infection, sarcoidosis, hemochromatosis, and autoimmune disorders (Al-Chalabi 2021). Low levels in men may be associated with sexual dysfunction and metabolic syndrome (Corona 2009).
High levels of prolactin are seen with pituitary adenomas and other prolactin-secreting tumors. Surges can also be seen with stress, illness, trauma, exercise, pregnancy, nursing, amenorrhea, hypothyroidism, kidney failure, PCOS, and anorexia nervosa. Levels can triple during sleep. Medications that can increase prolactin include antihistamines and histamine agonists, anticonvulsants, antinausea and antiemetic drugs, antipsychotics, MAO inhibitors, SSRIs, opiates, hormone therapy, antihypertensives, and illicit drugs (Pagana 2021).
Elevated levels of prolactin may be seen with hypertension and aortic stiffness (Zhang 2010), and higher levels can be associated with infertility in both men and women, and headaches and reduced libido in men (Al-Chalabi 2021).
Prolactin is a hormone produced primarily in the pituitary gland but can also be synthesized in the immune system, mammary glands, and uterus. Its primary function is the promotion of breast development and lactation in females though it also has effects in males (Al-Chalabi 2021). Additional physiological effects of prolactin include constriction of blood vessels, vascular smooth muscle cell proliferation, decreased production of nitric oxide, and stimulation of immune function and white blood cell adhesion (Zhang 2010).
Elevations in prolactin are associated with endothelial dysfunction and can increase risk of cardiovascular disease and cardiac events in renal failure where hormone clearance is diminished. Risk of a cardiac event may increase by 27% for each 10 ng/mL (212.7 mIU/L) increase in serum prolactin while all-cause mortality and cardiovascular mortality can increase by 12-15% (Carrero 2012).
Elevated prolactin in both men and women is observed in hypothyroidism. A mean level of 27.9 ng/mL (593.6 mIU/L) is seen during overt hypothyroidism versus a mean of 8.2 ng/mL (174.5 mIU/L) in euthyroid controls. Prolactin may also be elevated with subclinical hypothyroidism with a mean level of 14.1 ng/mL (300 mIU/L). Research indicates that treatment with L-thyroxine normalized prolactin levels in hypothyroid individuals (Goel 2015).
Review of data for menopausal women in the Nurses’ Health Study indicated that daytime levels of prolactin above 8 ng/mL (170.2 mIU/L) were associated with increased risk of hypertension though direct causation was not established. An increase of 1 standard deviation in prolactin level was associated with a 33% increase in hypertension risk (Zhang 2010).
Al-Chalabi, Mustafa, et al. “Physiology, Prolactin.” StatPearls, StatPearls Publishing, 29 July 2021.
Carrero, Juan Jesús et al. “Prolactin levels, endothelial dysfunction, and the risk of cardiovascular events and mortality in patients with CKD.” Clinical journal of the American Society of Nephrology : CJASN vol. 7,2 (2012): 207-15. doi:10.2215/CJN.06840711
Corona, Giovanni et al. “Hypoprolactinemia: a new clinical syndrome in patients with sexual dysfunction.” The journal of sexual medicine vol. 6,5 (2009): 1457-66. doi:10.1111/j.1743-6109.2008.01206.x
Dourado, Marclébio et al. “Relationship between Prolactin, Chronic Kidney Disease, and Cardiovascular Risk.” International journal of endocrinology vol. 2020 9524839. 22 Jun. 2020, doi:10.1155/2020/9524839
Goel, Parul et al. “Evaluation of serum prolactin level in patients of subclinical and overt hypothyroidism.” Journal of clinical and diagnostic research : JCDR vol. 9,1 (2015): BC15-7. doi:10.7860/JCDR/2015/9982.5443
Pagana, Kathleen Deska, et al. Mosby's Diagnostic and Laboratory Test Reference. 15th ed., Mosby, 2021.
Zhang, Luxia et al. “Plasma prolactin level and risk of incident hypertension in postmenopausal women.” Journal of hypertension vol. 28,7 (2010): 1400-5. doi:10.1097/HJH.0b013e328339f254