How does thyroid effect prolactin

Louie · 06-18-2003, 03:42 PM

I feel like screaming about my prolactin levels!! I had elevations in the past (up to 48) and had an MRI to rule out a prolactinoma in the brain. Since high prolactin can cause m/c and I've had two, my RE tested levels last month while I was in the midst of the hyperthyroid phase of postpartum thyroiditis. This time, my prolactin was LOW (only 4!). But 2 weeks ago, after a month of the hypo phase of thyroiditis and after 2 weeks on synthroid, my prolactin level was elevated again (28 on CD10 when highest normal level is 22). So, they want to retest again on CD3 of the next cycle. Does anyone here know if this is just elevated because of my thyroid swings? Does high prolactin sometimes just go along with PCOS too? Any help is appreciated, thanks!

shenacat · 06-18-2003, 05:38 PM

Hypothyroidism can cause high prolactin. I'm not sure how to fix it other than to be optimised on medication.

M_19 · 06-22-2003, 08:26 AM

Hi Louie, i'm a 2nd year medical student and i'll try to answer your question of how hyper/hypo thyroidism affects prolactin.

Your pituitary gland (at the base of your brain), produces Thyroid Stimulating Hormone (TSH), which stimulates your thyroid gland to produce thyroid hormones. Unfortunately, TSH also acts back on the pituitary gland and stimulates it to produce prolactin. So if you have high TSH, you'll have high Prolactin, and vice versa.

Basically, hyperthyroidism or hypothyroidism can be related to both low and high levels of prolactin.

If you are hyperthyroid, this may be caused by overproduction of TSH by your pituitary, in which case you'll have high prolactin. However, if the hyperthyroidism is casued by oversecretion by the thyroid gland, this will supress the amount of TSH produced by the pituitary and result in low prolactin levels.

Conversely, if you're hypothyroid, this can be casued by understimulation from your pituitary, ie, low TSH so low prolactin; or it can be casued by undersecretion of thyroid hormones by your thyroid glands, causing incresed secretion of TSH from your pituitary, and high prolactin.

very complicated i know, but hope that helps.

bananasmom · 06-25-2003, 07:38 AM

I always jump on these prolactin-type threads, as I failed to lactate with my dd.

M_19 - your explanation includes a lot about the pituitary, but it is rare that a doctor tests the pituitary, in treating the thyroid.

In most of the people I read about (here and at other message boards), we're treated based on TSH, with maybe an antibody or a T4 test here or there (I actually had a pituitary MRI, but I think that is unusual).

Am I reading this right?

Hyper, but with high TSH???

Quote:

hyperthyroid, this may be caused by overproduction of TSH by your pituitary, in which case you'll have high prolactin.

Hypo, but with low TSH???

Quote:

hypothyroid, this can be casued by understimulation from your pituitary, ie, low TSH so low prolactin.

In those cases, is that dx really hyperthyroid/hypothroid or is it a thyroid-something-or-other prpblem that is really a pituitary gland problem? It was my understanding that pituitary gland-thyroid problems were rare. I *think* most of us are thyroid disfunction people here, right?

M_19 · 06-29-2003, 09:44 AM

hi bananasmom

Regarding your first question about the pituitary - although doctors do not directly examine the pituitary when investigating thyroid disorders, TSH is one of the main hormones produced by the pituitary gland, so measuring TSH hormone levels is actually a pituitary function test. If your TSH levels are found to be significantly elevated and cannot be supressed by administering synthetic thyroid hormones(T4 and T3), then you'd probably be referred for a brain scan (MRI or CT) to chech for any pituitary tumours. But as you said, pituitary tumours are quite rare, although the thyroid disorder is normally cured after removal of the tumour.

Secondly, hyperthyroidism with high TSH is know as Secondary hyperthyroidism. its caused by overstimulation of yout thyroid, by excessive TSH produced by your pituitary. This may be due to a tumour, as mentioned above, or defects of the hypothalamus, which may be overstimulating your pituitary. (complicated, i know!!!)

Thirdly, hypothyroidism caused by low TSH is known as secondary hypothyroidism. It's caused by understimulation of the thyroid by the pituitary becasue the pituitatry is producing inadequade supplies of TSH. This may be due to damage to the pituitary gland, autoimmune disease of the pituitary, or understimulation of your pituitary by the hypothalamus.

So SECONDARY thyroid disorders aren't actually problems of the thyroid gland itself they're actually problems of the pituitary or hypothalamus. Treatment is therefor aimed at the pituitary and hypothalamus. PRIMARY thyroid disorders are disorders of the thyroid gland itself .

Basically, hypothalamus stimulates pituitary. Pituitary stimulates thyroid via TSH. thyroid produces T3 and T4.

Hope that helps

bananasmom · 06-29-2003, 01:38 PM

Quote:

(complicated, i know!!!)

Actually, it isn't

I am fairly well-informed about my thyroid and its related functions.

~~~

Louie - your shifts in prolactin seem to be in line with your TSH changes. I myself, failed to lactate, before my Hashimoto's dx. It broke my heart, I am always searching for more information about the thyroid and milk production. In my reading, I can find that PCOS and Hyperprolactinemia are 2 common causes of infertility (which I'm sure you already know).

At http://www.inciid.org/faq/pcos5.html#5.22 , I found:

Quote:

Hyperprolactinemia is an elevation of prolactin levels in the blood that may appear more often in women with PCOS. The elevated levels may cause breast discharge and may contribute to irregular menses. In some cases it is caused by a tumor on the pituitary gland. The first step in diagnosis is usually a blood test, and elevated levels may indicate further investigation through MRI. If the tumor is large and pressing on adjacent brain structures, it may be removed and all problems are solved. A small tumor might be treated with medications such as bromocriptine (Parlodel) or cabergoline (Dostinex — which is also shown to improve uterine perfusion. Cabergoline is often tolerated better than Parlodel, and doses are taken less frequently

There was a link on uterine perfusion, as well:

http://www.inciid.org/fertinews/carbergoline.html

More info at http://www.kathies-pain.com/ryan.htm :

Quote:

Prolactin excess has been associated with hyperandrogenism (often hirsutism) in a variety of circumstances. Prolactin may augment adrenal androgen secretion by the inhibition of 3beta-hydroxysteroid dehydrogenase activity or, less often, through selective action on the sulfation of DHEA in adrenal or extra-adrenal sites (Carter et al, 1977). However, prolactin inhibits FSH-induced ovarian aromatase, leading to intraovarian hyperandrogenemia. In hyperprolactinemic women (prolactin range, 36 to 991 ng/mL) studied by Glickman et al (1982), 40% had androgenic abnormalities of which the most common was elevated free testosterone levels. The next in frequency was depressed SHBG levels and then elevated DHEAS levels.

So, in answer to your original question, it does appear that some PCOS patients also suffer from hyperprolactinemia. I would push my doc to do a pituitary MRI, just to be sure.

If you do a google search for PCOS and hyperprolactinemia, you get a lot more links, I just surfed a couple.

HTH!