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Subclinical Hypothyroidism, High Prolactin and Erectile Dysfunction

Hi guys,

I originally went to my GP 9 years ago about erectile issues. My arousal response had become weaker and morning erections had stopped. She ran blood tests, and concluded that everything was normal.

Last month, I visited my new GP about an unrelated issue. This issue was difficult to diagnose, and as such a full panel of blood tests were ordered, showing the following:

TSH: 4.79
T4 free: 16.2
Testosterone: 9.7

This testosterone level is below the "normal" range and is less than half the mean value for a 27 year old male. The TSH level is way over the upper bound of the normal range.

Low testosterone makes sense. It explains the absence of morning erections. It is thought that these nocturnal erections play a role in healthy cavernous vasodilation, thus possibly partially explaining my weakening waking erections.

I got the test results from when I was 18. They showed a developing pattern:

TSH: 3.79
T4: 16.8
Testosterone: 12.5
Prolactin: 299

My TSH levels were above the normal range, my test levels were again roughly half what they should be and crucially, the prolactin level (while clinically normal) was still very high for an 18 year old when measured against mean values. I'm sure if my prolactin levels were measured last month, they would be very high.

Is this correct?:

- My thyroid is underfunctioning so my hypothalmus instructs my pituitary to produce more TSH
- Unfortunately this also causes the pituitary to produce more prolactin, a known dopamine inhibitor (thus weaking erectile response to arousal) and inhibitor of test production
- The increased levels of TSH seem to be keeping the T4 levels normal. More and more TSH is required to do this as I get older, therefore more prolactin is being produced, less testosterone is being produced and my libido and erectile health worsen as a result.

I'm also experiencing other hypothyroidism symptoms such as shaky hands and constant and worsening fatigue(despite being super fit). I also had my first ever migraine last month.

Has anyone had a similar experience? Thanks for reading.
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1756321 tn?1547095325
Lab ranges that have a wide range are ridiculous. :)

Total testosterone should be measured with sex hormone binding globulin (SHBG). Increased SHBG levels may be associated with hypogonadism in men and decreased levels can result in androgenization in women. My SHBG was deficient due to insulin resistance.

Besides standard labs docs usually (hopefully) will run such as complete blood count, liver, kidney, electrolytes, i would also add to your list thyroid peroxidase antibody, thyroglobulin antibody, vitamin D - 25(OH)D, vitamin B12, full iron panel, glucose, lipid panel.
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Avatar universal
Hi Red_Star,

Thanks for your post.

Testosterone figures are in nmol/L.

2013 lab range for testosterone is 9.9-52.4 - ridiculously wide I'm sure you'll agree.

The academic paper I read (Vermuelen, 1996) that gives mean values of test per age group is far more instructive I feel.

Prolactin wasn't tested this year. But the lab range in 2003 was 98-456. My reading of 299 was measured in uIU/mL.

I may have to wait quite a while for my endo appointment. But I have decided to get full blood tests done at my GP's office this Tuesday, so that I can present them to him at my first appointment. This I feel will speed up the process. Currently I plan to get the following readings done:

Free t3
Free t4



Anything else that I should be armed with for my endo appointment?
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1756321 tn?1547095325
Medhelp decided to post my answer before i was ready. *sigh* Okay not too many errors at least. One sentence is pretty garbled. It's meant to read: In males, hypothyroidism likely rises prolactin levels but not as significantly. :)

Helpful - 0
1756321 tn?1547095325
Could you list your lab ranges for testosterone and prolactin. In general, blood prolactin above 200 ng/ml almost always is diagnostic of a true prolactinoma. High prolacin lowers testosterone. And if your testosterone is also measured in ng/dL that is so low it's ridiculous! Research shows over 95% of euthyroid patients with no thyroid symptoms has a TSH under 2.5mU/L.  TSH is of no value with conditions that do not affect the thyroid such as central hypothyroidism and cellular resistance.

Swedish researchers investigated 219 patients suffering chronic fatigue for more than 1 year. Using fine needle aspiration (FNA) biopsy they found 87 of these patients had definite cytological lymphocytic thyroiditis (Hashimoto's thyroiditis). In other words, 40% of patients with chronic fatigue had proven Hashimoto's thyroiditis.  Of these 87 patients, 50 had a TSH level within the normal reference range and 37 where outside the reference range. The upper TSH limit at 5mU/L.  

TSH values were scattered (median 3 - 8 mU/L). All 87 patients were treated with thyroxine and proved favourable  favourable irrespective of baseline TSH . The study was published in The lancet Volume 357, No' 9260, 24 March 2001

In females, hypothyroidism is a common cause of elevated prolactin levels. I had elevated prolactin myself.  In males, prolactin will not rise as likely raises prolactin but not as significantly Elevated prolactin is very anti-testosterone.

My labs took 4 years (after my first notable Hashimoto's thyroiditis symptom) to show subclinical hypothyroidism -  TSH of 6 mU/L and a free T4 of 13 pmol/L. I also have had cellular resistance issues for over 24 years at least with no lab changes. Suffering in "normal" ranges is the hazard of conventional medicine.

Excerpt from Life Extension - The Testosterone Controversy...

"When Life Extension conducted a study of its members free testosterone blood levels two years ago, a startling 86% of the men had less than 15 pg/mL of free testosterone, placing them at high risk for virtually every age-related disease.

Free testosterone is the biologically active form of this hormone measured in the blood. When looking at total testosterone blood levels, one should strive for a moderately youthful range of 700-900 ng/dL, though conventional reference ranges state that levels as low as 193 ng/dL are sufficient, a range that we at Life Extension believe is woefully inadequate."
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