Following some discussion, I thought I would give this topic a thread of it's own
A lot of people worry about erectile dysfunction and get to treating things that may or may not be causing it. Prolactin becomes an obvious candidate when bloodwork is done and elevated levels are spotted.

This is a reasonably short, quick, limited and biased literature review, coupled with an unbiased and brief analysis of some of the bloods I could find here on eroids.com to try to understand whether Prolactin (Prl) is or isn't directly or indirectly causing erectile dysfunction, and whether or not we really need to worry about tumours in cases of elevated prl.

Some of the limitations are my blatant bias against prolactin, toward test/estro and the limited time spent gathering both literature and bloodwork data on eroids,com. I recognise that any pubmed warrior can gather abstracts supporting any point they wish to make, but to counter this have tried to gather only fully accessible articles/blogs/journal reports, and to be unbiased when presenting bloodwork cases/data. Another limitation is our beloved ranges! Ranges for high prl range (pun intended) from a so-called normal of <20ng/ml in the lit reviews, to ~18 according to TRT experts, and ~16 on some bloodtest give or take. I have proceeded on the basis of >20ng/dl being high, with 15-20 being elevated which I think is reasonable. Another limitation is the lack of data in some bloodwork cases, a lack of images of actual lab test results. Another limitation is the lack of literature on AAS users, although this is somewhat countered by the bloods review.

I have included a basic summary at the beginning as this is pretty long, however basic. I would recommend reading through it though as the sources of lit are interesting as are the blood results. It's worth looking at properly and shouldn't take too long.

Hopefully this helps some manage their hormones, and doesn't get me too bashed up by the naysayers! As always I am 100% open to evidence based counter arguments on anything and only find that to support developing best practices/good protocols

High prolactin and Erectile Dysfunction... a case for fact versus fiction, a lit review and eRoids bloodwork review

On physiologically high prolactin (hyperprolactinemia).... hyperprolactinemia is often caused by macroadenomas (10 mm or larger) which are more common in men. A prolactinoma is likely if the prolactin level is greater than 250 ng/mL and a level of 500 ng/mL or greater is diagnostic of a macroprolactinoma. Selected drugs including risperidone and metoclopramide may cause prolactin elevations above 200 ng/mL.
(https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3853872) and (https://www.ncbi.nlm.nih.gov/pubmed/20039901 and https://www.ncbi.nlm.nih.gov/pubmed/11155212)

So mild hyperprolactinemia is usually >20, to 50 ng/mL range and men with hyperprolactinemia may present with erectile dysfunction (although the literature doesnt specify high vs mild)
(http://www.clevelandclinicmeded.com/medicalpubs/diseasemanagement/endocr... AND https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3853872)

But... sexual dysfunction is not caused by high prolactin
(https://www.ncbi.nlm.nih.gov/pubmed/18082071)

Conflicting evidence? I don't think so, bear with me... I searched through a boatload of blood reports of high prolactin here on eRoids... I was not selective and just went with what i saw, 1 by 1 and took data that was relevant and included everything for a certain amount pages before I almost went blind! This be them:

1. 5 months post cycle, following gyno and a letro caber run 30 days post cycle, no mention of pct... Listed high Prl, but is only at upper end of most scales, so elevated. This blood work suggests a 30day post cycle/last inj letro/caber run (no full pct details) for gyno would have lowered prl (16.4 ng/ml from an even higher level (who knows, so must keep digging for on-cycle results). However, it is important to note that letro will have smashed an elevated E2 level which is now mid way on the listed scale. Suggest perhaps it was sky high post cycle, supporting/supported by existence of gyno dev, or he is a huge aromatiser, went zero and rebounded all the way bgack up to midway (less likely on its own given gyno or else both together are plausible). -- (https://www.eroids.com/pics/prolactin-blood-test-feedback)

2. On blast cycle bloods elevated prl at 17, estro through the roof, libido problems -- (https://www.eroids.com/forum/steroids-qa/pct-anti-estrogens/prolactin-is...)

3. TRT blast high prl at 18.1, no E2 / test reading, but other forum posts indicate possible serial estrogen offender (disclaimer: speculation on my behalf) -- (https://www.eroids.com/forum/general/general-talk/prolactin-too-high-now...)

4. High prl, low free and total test with low libido, used clomid to recover and libido sorted -- (https://www.eroids.com/forum/steroids-qa/pct-anti-estrogens/low-testoste....)

5. On cycle bloods, elevated prl at 20.2, but high test and no libido issues -- (https://www.eroids.com/forum/steroids-qa/pct-anti-estrogens/high-prolact...)

6. Pre first cycle high prl levels at only 20.9 caused by a medication but no libido issues mentioned -- (https://www.eroids.com/forum/steroids-qa/steroid-cycles/first-cycle-look...)

Conclusion:
We can probably but not definitely rule out tumours as a cause of high prolactin, just not entirely as it is still a consideration in rare cases and we are all about health here on eRoids, so bloodwork is essential to ascertain blood levels and possibly a brain scan for tumours, in the case of levels listed in the lit review.

In all presented eRoids bloodwork cases listed, none had prolactin levels so high they are likely to be tumour related, although some were technically classed as hyperprolactinemia - still, this cannot be completely ignored. In all cases, prolactin was either elevated to upper end of range, or high at literally just over the 20ng/ml upper point. In SOME/the majority of cases there were libido issues but not all - interestingly one case showed high prolactin and no libido issues. In ALL of these cases of elevated or high prl was accompanied by high estro and/or low testo, low fsh/lh, with 1 case sorted by clomid therapy, 1 case high prl pre-cycle. There were 2 cases of high prolactin with high or normal testosterone levels and no libido issues.

It seems to be the case that there is a lot of bloodwork evidence here to prove that high prolactin does not cause ED directly, but perhaps indirectly by lowering testosterone, and that ED can exist in high prl cases primarily where there is low test, high estro and also in cases of hyperprolactinemia, and cases not attibuted to AAS including both pituitary tumours and also in (1 year) off-cycle AAS users and for an unidentifiable cause in a non-AAS user.

This said, the evidence is so limited it is restrictive in helping form the complete picture.