Category Archives: 21. Sexual Health

Prolactin, A Problem for Older Guys

Prolactin, A Problem for Older Guys

References: Jr of Endocrinology, Wikipedia, Nature Reviews,

Ever heard of prolactin? Bet not. From its name, you can surmise that it has something to do with helping lactation: “pro” – lactation. And that’s just what it was discovered to do. It is secreted from the anterior pituitary in response to breast stimulation, and helps milk let down. A mother can successfully breast feed when she has her infant stimulate her nipple. That was figured out in the 1970s. Since then, we have found over 300 other functions that in which it participates.

Prolactin isn’t just made in the pituitary. It’s made in lots of other places in much smaller amounts. It is quite similar in structure to growth hormone, nature being efficient with hormone design and building off one hormone to make more functions. It has 198 amino acids in it, so is a peptide hormone. As we dig deeper into biology, we are finding that the human metabolism is far more complicated than anything we ever imagined. Orgel’s Third Law alludes to that: Nature is more complicated than you imagine, even when you take Orgel’s Third Law into account.

Now, here’s the rub. One of it’s functions is men’s refractory period. The refractory period is the time after an orgasm during which a man is unable to be aroused again, cannot achieve an erection, and would rather read a book. That period is usually short in teen years (5 minutes) but gradually lengthens with age. With the right environment, it might only be a few minutes – hours in the 20-3os. By the age of 50-60, it can be a few days. Prolactin appears to be the mediator of that refractory period. As men age, their prostate gland enlarges, and the prostate also makes prolactin.

That’s where this week’s study comes in. Ten men in Germany, who were otherwise healthy, had their prolactin measured and then shown erotic films and instructed to masturbate. This is hard to turn into a double blind trial, as you can imagine, so it was single blinded and crossed over so that then subjects didn’t know when they were getting a prolactin inhibitory drug called cabergoline. The cabergoline arm of the study was found to have significant reductions in prolactin, and enhanced of all parameters of sexual drive (<0.05), function (<0.01) , and perception of length of the refractory period (< 0.01). The authors suggest that this is a possible route for study as we look into future effects on men’s sexual health.

Prolactin has over 300 actions in the body. It may play a role in brain cells making myelin, it probably mediates women’s infertility while breast feeding, in infants making surfactant in their lung, in immune tolerance of the mother’s immune system to the fetus, the production of new brain cells… Orgel had it right. Nature is complicated, and we are just unpacking the surface. The interplay still to be discovered has a way to go.

WWW. What will work for me. Well, it turns out cabergoline is now a drug on the market used for men’s sexual health called Dostinex. And we are finding the measurement of prolactin starting to seep into standard blood assays. In my practice, my most used blood panel has it as a newly added feature, and I’m finding a lot of men and women have modestly elevated levels. I tell folks that a tiny percentage may have a pituitary tumor, but what to do with slightly elevated levels is still uncertain. There are web sites on how to lower it naturally for both men and women.

Pop Quiz

‪1. Prolactin is a hormone that helps women breast feed their infants. T or F T.

That is what it was discovered to do

‪2. Elevated prolactin plays a roll in some men who have sexual dysfunction. T or F

Again, true.

‪3. Prolactin is secreted at the end of a sexual encounter and accounts for the sense of satisfaction afterwards and the inability to become aroused again. T or F


‪4. It is easy to measure prolactin. T or F

‪It is almost becoming routine, and lots of folks have modestly elevated levels.

‪5. Prolactin causes cancer. T or F

Whoa Nellie. Not so fast. It may be a growth factor for some cells, and cancers tend so shop around and find what growth factors they can use. Prolactin is similar in structure to growth hormone, but it isn’t really a cancer causer.

Testosterone and the Risk of Alzheimer’s in Men

Testosterone and Risk of Alzheimer’s in Men

Reference: Moffat Neurology 2004,

Testosterone, all about men’s sexual health, right?   Well, that is true, and it certainly is what most men think is most important, but it’s certainly not all. And here we have today a reference study of the importance of testosterone to men’s brain health.

The Baltimore Longitudinal Study of men’s health started in 1958 and followed men for a mean of 19.1 years, and as long as 37 years. They had physical exams with neurological testing and blood work every other year.   Five hundred and seventy four men were included in the Alzheimer’s and testosterone study group.   That is a pretty strong sample group, for a pretty long time, so this study should have something valid to say.   After accounting for all possible confounding variables, like diabetes, cancer, smoking, age, education, hormone supplements and the like, they were left with the connection between testosterone levels and risk for Alzheimer’s.   Total testosterone and sex hormone binding globulin didn’t seem to have any connection with Alzheimer’s, but free testosterone did.   In fact, for every 10 nmoles increase in free testosterone, there was a 26% reduction in risk for the development of Alzheimer’s.

What is free testosterone? It is the proportion of testosterone in your blood that is available for your tissue to actually use.   Here is the explanation.   Testosterone is built from the cholesterol molecule.   Cholesterol is in the fat family, meaning it is not water soluble. If it isn’t water soluble, it can’t be moved around the body in the transport system we call blood. Blood is made of water and fat doesn’t dissolve in water. The human body has come up an ingenious method of moving it. Sex hormone binding globulin is that method. It is a protein, made in the liver, that has an internal pocket that welcomes fat; it is “hydrophilic”.   High levels of insulin and growth hormone lower it, whereas estrogen and thyroxine raise it. It needs zinc to hold itself together in the form that binds it.

These other hormones don’t need to change it much to have a big impact.   Considering that you only have about 0.1-0.3% of your total T as the “free” stuff, it only takes a small shift to alter your natural free T. There is some debate as to what a proper free T should be, but this is where the rubber meets the road. Many physicians consider a free T3 of 8 pg to be enough.   Well, I have come to recognize that it takes at least 35 pg to feel really good.   Many good things happen then? Remember the male brain?

Now, if we apply that metric to the above study, we will find that the house of medicine will give you a clean bill of health with a free T of 8 pg. But it we raise you to 38pg, that is 3 notches of 10 pg each, and that will lower your risk of Alzheimer’s by 78%.

Well, wait a minute.   The above study shows that men who have higher free T on their own have less risk of Alzheimer’s.   That is not to say that we can prove that raising it by outside means will lower your risk. It isn’t the same thing. There may be other reasons you have high free T3 and those other reasons then account for your lower risk. And giving you T may not provide those other reasons.   So, it’s not yet proven, and likely will never be because there is no money in it. But you will either feel better, or not care because your brain is happy.

www.What Will Work for Me?   I’m interested in this. I have a mother with Alzheimer’s.   I want my free Testosterone to be optimal. It’s something every man should be paying attention to.


Pop Quiz


  1. For every 10 pgram increase in Testosterone, men have a 26 percent increase in risk for Alzheimer’s Disease? T or F

False. You didn’t read the article. That’s backwards. DECREASE

  1. Optimal Levels of Free T3 in a man are around 8 picograms. T or F

False. We want you at least 32 picrograms

  1. Sex Hormone Binding Globulin can muck things up by making your free T3 be all bound up? T or F


  1. You can raise SHBG by having too much estrogen. T or F


  1. You have have too much estrogen by being overweight? T or F