Hyperprolactinemia as a Side Effect of Long-Acting Injectable Risperidone Therapy or a Symptom of Klinefelter Syndrome - a Diagnostic and Therapeutic Dilemma.

Risperidone, as a potent antagonist of the serotonin 5-HT2 receptors, as well as of the dopamine D2 receptors, is presumed to have a major antipsychotic effect. Treatment of patients with acute psychosis most often includes the use of long-acting injectable risperidone. A number of placebo-controlled studies have shown that risperidone solution is well tolerated and that it has many advantages, including a rapid elimination of both positive and negative symptoms of schizophrenia, as well as a low risk of experiencing extrapyramidal symptoms, compared to therapies with classic antipsychotics such as Haloperidol (Yosimura 2005). However, Risperidone can block the D2 receptors in the pituitary gland resulting in hyperprolactinemia, which is dosedependent (Timotijevic 2008). Klinefelter syndrome belongs to a group of congenital primary hypogonadisms and it is a disorder which affects the development and structure of the testicles. It is the most common form of disorder of sexual differentiation which affects 1 in 500 men and is due to the presence of one or more extra copy of the X chromosomes in each cell, usually a karyotype is 47,XXY (classic shape) or 46,XY/47,XXY (mosaicism). Klinefelter syndrome is characterized by small, hard testicles, azoospermia, gynecomastia, a low level of testosterone (testosterone is the hormone that directs male sexual development before birth and during puberty and low level can lead to delayed or incomplete puberty), and a high level of gonadotropin in the plasma of males with two or more X chromosomes (Harrison et al. 2004). The clinical diagnosis of this syndrome is not easy to discern, which makes it hard to recognize children with Klinefelter syndrome symptoms at an early age. Often the first signs of the syndrome are noticed at puberty in form of insufficiently developed secondary sexual characteristics and gynecomastia. Sometimes it can be detected at an older age, during infertility testing. Children with this syndrome can have a low IQ or mild retardation, and they tend to be taller than their peers at this age (Stepanovic et al. 2001). The other characteristics entail psychosocial problems, a greater tendency towards malignant diseases and a high risk of cardiovascular diseases (Jaksic 2008). This case study reviews the dilemma the authors encountered during the treatment of psychotic disorder. Was hyperprolactinemia caused by long-active injectable risperidone or was it a symptom of Klinefelter syndrome?