Prolactin Queries

[pamelatransuk]

I have been on HRT since February under medical supervision and have Blood Tests performed each quarter. I was also informed at the start that subsequently there would be Blood Tests for Prolactin aswell as the Estrogen and Testosterone. However my first BTs included Prolactin anyway and I was told my E & T BTs could wait for 3 months but my Prolactin BT must be done after 2 months (meaning 5 months after start of HRT).

I just have a few simple questions on Prolactin tests if I may please:

1. Is it true that as T reduces, Prolactin should rise? Therefore when T approaches zero, should Prolactin reach its maximum?

2. Is it true that as E rises, Prolactin should also rise? Therefore should Prolactin should rise till E is in normal transition to female range and then settle down within reason?

3. Should age be a significant factor in the relevance of Prolactin levels for MTF transitioners?

4. Am I right to assume that high Prolactin could result in thyroid problems and as I have had thyroid tests 18 months ago which proved negative, is it worthwhile to pursue further thyroid tests if my Prolactin remains high?

5. Please confirm normal Prolactin levels should be in International Units under 350 Mu/L for men or under 500 Mu/L for women.

6. Do you know of the expected Prolactin level in US units?

Just for the record my Prolactin level after 3 months was 461 Mu/L and my E was 922 pmol/L and my T was 1.6 nmol/L.

Thanking you for any help you can provide and just to put your minds at rest, I am not worried at this stage concerning my Prolactin level but I wish to be prepared if necessary for possible future medical problems.

Pamela

[KayXo]

Prolactin will rise as a function of both estrogen and progesterone levels. Levels go way up during pregnancy due to high levels of estradiol and progesterone, up to 12766 mIU/L or 600 ng/ml. This is perfectly normal and to be expected. High prolactin levels are more a concern if you are on certain types of anti-androgens such as cyproterone acetate or other non bio-identical progestogens/estrogens, as this can indicate a prolactinoma. As far as I know, thyroid function is not impacted but check with your doctor to be sure.

I've had levels as high 130 ng/ml or 2766 mIU/L due to high progesterone and estradiol levels. If doctors see no reason to panic when this happens to pregnant women, then the same should occur with us. And indeed, my doctor did not worry when my levels got so high. Later, they dropped as my estradiol and progesterone levels dropped.

p.s.: prolactin levels are also high after pregnancy and are maintained as long as there is breastfeeding due to suckling.

[KathyLauren]

These are questions you should probably ask your doctor or endo. 

I didn't know anything about prolactin until my checkup before last, when my doctor was worried that mine was getting a bit high.  I don't know what units the lab uses (they tend to use molar measures rather than weight measures), but 29 was high.  It came back down to 25 on my last checkup, so she was happy.

I don't know if it is the presence of E or the lack of T that increases it.  I don't remember my doctor talking about thyroid problems, but she did say that if my level went much higher than 29 whatevers per whatever, I might start lactating.

[KayXo]

she did say that if my level went much higher than 29 whatevers per whatever, I might start lactating.

At 130 ng/ml, I never lactated. This is because both progesterone and estrogen usually inhibit lactation. When they both drop after pregnancy, lactation occurs.

[pamelatransuk]

Thank you ladies for your kind replies and I shall speak to my doctor after next Prolactin Blood Test on 23July.

Thank you also for providing method of conversion which is to divide International by 21.28 for US or to multiply US by 21.28 for International.

Hugs

Pamela

[Michelle_P]

I've had high prolactin levels by the standard test for quite a while.  The likely source in my case was a small adenoma on the side of the pituitary gland, identified by MRI scans after the high prolactin level was first found.  The little monster is probably a prolactinoma.

Normal for AMAB is 0-18 ng/ml; my levels:

Before HRT: 30 ng/mL and 34 ng/mL
2 days into estrogen: 40 ng/mL
4+ weeks on estrogen: 38 ng/mL

Ah, but the standard prolactin test isn't clever enough to tell the difference between monomeric prolactin, the stuff that helps us start nursing, and the giant macroprolactin molecules often produced by a prolactinoma that are inert.  A chromatographic test that separates them shows monomeric prolactin at 9 (normal range 3.4-14..  So my little monster is just a boring microprolactinoma and won't be causing me any problems with growth or lactation.

There's a really cheap test that measures the amount of actual real prolactin, compared to macroprolactin, huge molecules that test like prolactin but are actually inert and harmless.  You might nudge your endocrinologist to try that test.  It takes several days to get results back, but it can do wonders to set your mind at ease. (Macroprolactin, Serum; Test ID MCRPL)

If the microprolactinoma does grow, there is another medication I can take for a while that has very good results in shrinking these growths. 

[pamelatransuk]

Thank you Michelle for this worthwhile information.

Pamela

[pamelatransuk]

Hello again

My Prolactin level was 461 (Intl) or 21.7 (US) on 23May.

Just to let you know my Prolactin level was 534 (Intl) or 25.1 (US) on 23July.

I saw my GP today to discuss and am happy with the outcome. He is both writing to my Endo about it but also given me the Blood Test Form for the six monthly full check up including E & T & Prolactin & Thyroid which are due anyway 8Aug.

I shall keep you informed.

Hugs

Pamela

[Cindy]

I'm glad everything is OK.

Checking prolactin levels is a cheap and easy way of having a look at the pituitary gland. It is a rather important endocrine gland but a bit of a beast to assess. A prolactinoma, resulting in abnormal prolactin levels is often the first sign that something is going on with it and may warrant further investigation.
They would then involve further biochemistry tests and MRI etc which can be expensive.

Thyroid function is also easy to test for and can be a useful indicator of a biochemical abnormality if a person starts feeling tired or lethargic or has personality changes.

[pamelatransuk]

Thank you Cindy for your kind words.

Just to confirm that physically I feel fine.

I shall update after my next appointment with my GP in 3 weeks time.

Pamela

[pamelatransuk]

I am sorry I forgot to update this thread in August.

My Prolactin level had risen to 622 (Intl) 29.2 (US) on my Blood Test of 14Aug. My Endo said no further action at that point but could continue to monitor in future quarterly BT results.

I am glad to say my Prolactin has reduced to 198 (Intl) 9.3 (US) on my BT of 12Nov.

I was never particularly concerned but this is nevertheless a relief.

Hugs to all

Pamela