From the Guidelines
Elevated prolactin levels are directly correlated with low testosterone production, and treating hyperprolactinemia is essential to restore normal testosterone levels. The relationship between prolactin and testosterone is well-established, with high prolactin levels inhibiting gonadotropin secretion via inhibition of the hypothalamic hormone kisspeptin, as noted in a recent study 1. This inhibition leads to reduced secretion of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) from the pituitary gland, resulting in decreased testosterone synthesis and hypogonadism. Some key points to consider in the diagnosis and management of hyperprolactinemia include:
- Measuring serum prolactin levels is crucial in patients presenting with symptoms such as delayed puberty, galactorrhoea, or menstrual disturbances, as recommended by a consensus guideline 1.
- Dopamine agonists like cabergoline or bromocriptine are effective treatments for hyperprolactinemia, with the goal of normalizing prolactin levels and restoring normal testosterone production 1.
- Regular monitoring of prolactin and testosterone levels is necessary during treatment to assess the effectiveness of therapy and adjust the treatment plan as needed.
- The correlation between prolactin and testosterone levels is significant, as many symptoms attributed to low testosterone may actually be caused by undiagnosed hyperprolactinemia, highlighting the importance of prolactin measurement in hypogonadism evaluation 1. It is also important to consider other potential causes of hyperprolactinemia, such as certain medications, primary hypothyroidism, or chronic kidney disease, as noted in recent studies 1. However, the most recent and highest-quality study 1 provides the strongest evidence for the correlation between prolactin and testosterone levels, and its recommendations should be prioritized in clinical practice.
From the Research
Correlation between Prolactin Levels and Testosterone
The relationship between elevated prolactin (hyperprolactinemia) levels and low testosterone (hypogonadism) production is complex.
- Hyperprolactinemia can induce hypogonadism by inhibiting gonadotropin-releasing hormone pulsatile secretion, which in turn affects follicle-stimulating hormone, luteinizing hormone, and testosterone pulsatility 2.
- This can lead to spermatogenic arrest, impaired motility, and sperm quality, resulting in morphologic alterations of the testes similar to those observed in prepubertal testes 2.
- Men with hyperprolactinemia often present with symptoms directly related to hypogonadism, such as impaired libido, erectile dysfunction, diminished ejaculate volume, and oligospermia 2.
Effects of Hyperprolactinemia on Testosterone Production
- Hyperprolactinemia can disrupt ovarian function in women, leading to hypogonadism, and this is also true for men 3.
- The mechanisms by which prolactin disrupts gonadal function are not fully understood but may involve altering hypothalamic neurotransmitter content through a direct feedback mechanism, resulting in a decrease of Gn-RH 3.
- In some cases, testosterone replacement therapy can actually induce hyperprolactinemia, possibly due to the aromatization of exogenous testosterone to oestradiol, which stimulates the release of prolactin by the anterior pituitary 4.
Treatment and Recovery from Hypogonadism
- Treatment with dopamine agonists, such as bromocriptine or cabergoline, can be effective in men with prolactinomas, leading to improved gonadal function and recovery from hypogonadism 2, 5.
- The extent and timeline of gonadotropic axis recovery in men with prolactinoma treated with dopamine agonists are still unclear, but recovery from hypogonadism can occur in a significant proportion of patients, especially during the first year of treatment 5.
- Factors such as the presence of visual field deficit, lower testosterone levels at baseline, and testosterone levels below 7.4 nmol/l at 6 months can predict persistent hypogonadism 5.