Three studies on the harmful effects of low prolactin

Discussion in 'Men's Health Forum' started by Structure, Mar 14, 2011.

  1. Structure

    Structure Member

    Gonzales GF, Velasquez G, Garcia-Hjarles M. Hypoprolactinemia as related to seminal quality and serum testosterone. Arch Androl. 1989;23(3):259-65. Hypoprolactinemia as related to seminal quality an... [Arch Androl. 1989] - PubMed result

    Semen quality and serum testosterone were studied in six men with hypoprolactinemia (less than or equal to 6 ng/ml) and in normoprolactinemic controls. The incidence of hypoprolactinemia in 92 men attending an infertility clinic was 7.5%. Males with hypoprolactinemia showed in high percentage of disorders (oligozoospermia, 50%; asthenospermia, 75%; hypofunction of seminal vesicles, 67%; and hypoandrogenism, 67%). Hypoprolactinemia is a clinical disorder associated mainly with poor sperm motility.

    Ufearo CS, Orisakwe OE. Restoration of normal sperm characteristics in hypoprolactinemic infertile men treated with metoclopramide and exogenous human prolactin. Clin Pharmacol Ther. 1995 Sep;58(3):354-9. Restoration of normal sperm characteristics in hyp... [Clin Pharmacol Ther. 1995] - PubMed result

    We investigated the effects of induced increase in prolactin levels on spermatogenesis in 20 infertile men with hypoprolactinemia using exogenous human prolactin (hPRL) and metoclopramide. The subjects were selected from a population of 175 infertile men in whom the prevalence of hypoprolactinemia was 33.14%. Mean basal plasma prolactin was 2.79 +/- 0.62 in the infertile men and 9.57 +/- 2.14 in the normal control subjects. At the sixteenth week, mean plasma prolactin was 9.41 +/- 1.3 in subjects treated with exogenous hPRL and 5.2 +/- 0.7 in subjects treated with metoclopramide. Mean basal sperm concentration was approximately 8.8 million per milliliter in the infertile men and 41.5 million per milliliter in the normal control subjects. Mean sperm concentration was approximately 37 million per milliliter in subjects treated with exogenous hPRL, whereas the peak mean value was 23 million per milliliter in subjects treated with metoclopramide for 16 weeks. At basal conditions, the mean percentages of abnormal sperm were 66.75% +/- 14.93% and 21.36% +/- 4.78% in infertile and normal subjects, respectively. In subjects treated with exogenous hPRL and metoclopramide, the mean percentage of abnormal sperm were 24.7% and 31%, respectively, at week 16. Mean plasma prolactin, mean sperm concentration and the mean percentage of abnormal sperm were 3.3 +/- 1.4, 7 million per milliliter, and 60.5, respectively, in the infertile subjects after drug withdrawal at week 14. In normal control subjects, there was no significant difference (p = 0.01) in the plecebo effect. We therefore conclude that the low prolactin levels in this group of infertile men may be one of the primary causes of their infertility.

    Corona G, Mannucci E, Jannini EA, Lotti F, Ricca V, Monami M, Boddi V, Bandini E, Balercia G, Forti G, Maggi M. Hypoprolactinemia: a new clinical syndrome in patients with sexual dysfunction. J Sex Med. 2009 May;6(5):1457-66. Epub 2009 Feb 10. Hypoprolactinemia: a new clinical syndrome in pati... [J Sex Med. 2009] - PubMed result

    INTRODUCTION: The physiological role of prolactin (PRL) in male sexual behavior is poorly understood. Conversely, the association between PRL pathological elevation in both reproductive and sexual behavior is well defined.

    AIM: The aim of the present study is to assess the correlates of normal PRL (PRL < 735 mU/L or 35 ng/mL), in male subjects consulting for sexual dysfunction.

    METHODS: A consecutive series of 2,531 (mean age 52.0 +/- 12.9 years) subjects was investigated. Patients were interviewed using the structured interview on erectile dysfunction (SIEDY), a 13-item tool for the assessment of erectile dysfunction (ED)-related morbidities. Middlesex Hospital Questionnaire was used for the evaluation of psychological symptoms.

    MAIN OUTCOME MEASURES: Several hormonal (testosterone, thyroid stimulation hormone, and PRL) and biochemical parameters (glycemia and lipid profile) were studied, along with penile Doppler ultrasound (PDU) and SIEDY items.

    RESULTS: After adjustment for confounders anxiety symptoms decreased across PRL quartiles (I: <113 mU/L or 5 ng/mL; II: 113-156 mU/L or 5.1-7 ng/mL; III: 157-229 mU/L or 7.1-11 ng/mL; IV: 229-734 mU/L or 11.1-34.9 ng/mL). Patients in the lowest PRL quartile showed a higher risk of metabolic syndrome (MetS; odds ratio [OR] = 1.74 [1.01-2.99], P < 0.05), arteriogenic ED (peak systolic velocity at PDU < 35 cm/sec; OR = 1.43 [1.01-2.03], P < 0.05), and premature ejaculation (PE; OR = 1.38 [1.02-1.85]; P < 0.05). Conversely, comparing subjects with PRL-secreting pituitary adenomas (N = 13) with matched controls, no significant difference was observed, except for a higher prevalence of hypoactive sexual desire in hyperprolactinemia.

    CONCLUSIONS: Our findings demonstrate that, in subjects consulting for sexual dysfunction, PRL in the lowest quartile levels are associated with MetS and arteriogenic ED, as well as with PE and anxiety symptoms. Further studies are advisable in order to confirm our preliminary results in different populations.
  2. seeking

    seeking Junior Member


    I am wondering if the low PRL in those patients is a result of some other malfunction that is going on and causing the other issues though

    I'd be curious to see a study on drug induced low prolactin
  3. Structure

    Structure Member

    Notice that in the second study, sperm returned to normal when prolactin levels were brought back up to a normal level. That at least shows that the low prolactin itself was harmful, even if it is not known what was causing the low prolactin.
  4. seeking

    seeking Junior Member

    if low sperm is what you would consider "harmful"
  5. Structure

    Structure Member

    Well, yes; if something is making you infertile, I'd say it is doing you harm. But I think you're missing the point. There's been discussion about what normal prolactin levels are. If your prolactin levels are so low that you've become infertile, then chances are its too low.

    I think some people on this forum are hypervigilant about lowering their prolactin levels because they are desperate to correct their ED (or are just insecure about libido when they don't even have ED). My point has been to show that going too far towards either extreme of the physiological range is bad.