Antipsychotics cause prolactin elevation by blocking the activity of dopamine at the D2 receptors (1). The presence of dopamine at these receptors inhibits the secretion of prolactin (2). The exact level of prolactin elevation varies between antipsychotic to antipsychotic based on their affinity for the D2 receptors (2).
Tolerance can develop to this particular side effect with chronic antipsychotic
therapy (i.e.: it may become less pronounced over time) (1). Prolactin levels return to base line within 2-3 weeks of discontinuation of an antipsychotic (1).
Long-term health consequences of hyperprolactinemia
Elevated prolactin levels may cause other side effects, such as bone density decrease (1)(2). However, the notion that this particular event occurs as a result of hyperprolactinemia is controversial, and may occur for other reasons such as lifestyle factors (1)(2). Decreased bone density increases the risk of bone fractures. Fractures in the spine or hip are of high concern because they can result in disability, and a higher risk of death (3).
Hyperprolactinemia is associated with hypogonadism (2). Hypogonadism may prevent normal development during puberty (4).
In women, there is some concern that hyperprolactinaemia may increase the risk of breast cancer (2). Although this idea is also controversial (1)(2).
- Hyperprolactinaemia and Antipsychotic Therapy in Schizophrenia http://www.medscape.com/viewarticle/468929_4
- Hyperprolactinaemia With Antipsychotics http://www.medsafe.govt.nz/profs/PUarticles/hyperpro.htm
- Osteoporosis - Symptoms and causes http://www.mayoclinic.org/diseases-conditions/osteoporosis/symptoms-causes/dxc-20207860
- Male hypogonadism http://www.mayoclinic.org/diseases-conditions/male-hypogonadism/symptoms-causes/dxc-20248457