Abnormal Prolactin Level - Does it Automatically Indicate Prolactinoma?

As earlier discussed in the article, "Pituitary Tumor: Bromocriptine Reverses Early Symptoms of Excess Prolactin," my astute family physician detected a health issue I had - my pituitary was releasing an overabundance of prolactin into my bloodstream.

Through a combination of blood tests and Magnetic Resonance Imaging evaluation, he revealed I had a pituitary tumor. He initiated treatment, prescribing bromocriptine to reduce prolactin, and coupled it with a referral to an endocrinologist and neurologist at a nearby teaching hospital.

One additional pituitary find was a slight depression in TSH (Thyroxine Stimulating Hormone) level. He elected not to treat that, feeling it would improve when the other problem was dealt with.¹

Specialists Take a Look

Today, July 1, 2009, I met with the two specialists. First I saw the endocrinologist - a truly inspired professional. Because he realized I am a chemist, he was willing to go technical with me. I present a simplified report of what he said to you, as it may assist some reader with a similar problem.

The Experts "Testify"

My blood test indicated my prolactin was 116. This, while high, is not as typically high a prolactin level as most sufferers of prolactinoma. Numbers in the 200 range are much more typical. The MRI showed a definite tumor - a macroadenoma, as compared to a smaller microadenoma. The doctor said my tumor might actually be more of a nuisance tumor - one merely crowding surrounding tissues of the brain, perhaps putting impeding proper function of that tissue. Fortunately, my tumor did not grow upwards, putting pressure on the optic nerve, or my vision would have been at risk. Rather, it grew toward the left ear, putting pressure on other tissue. Eventually, growth in that direction would produce different problems.

Bromocriptine or other medication designed to reduce prolactin will reduce prolactin even if there is no prolactinoma. However, if my tumor is not a prolactinoma, it will not reduce the size of the tumor, and it will continue to grow. Thus, as a course of action the endocrinologist decided to continue my medication for six months (although with a change from bromocriptine to cabergoline to reduce side-effects). At that time, another MRI will be performed. If the tumor is smaller, well and good - I had a prolactinoma after all, and I just continue taking medication. If - and this appears more likely - it does not shrink but goes on growing, I will need to choose one of several options.

The neurologist agreed with the endocrinologist, and said that if it does not significantly shrink, he will encourage me to consider surgery to remove the tumor.

So, "Does an abnormal prolactin level automatically indicate the existence of a prolactinoma?" The answer is "No, it does not."

^{1 See the article, Hypothyroid by Pituitary Adenoma Tumor Limiting TSH Production - My Story.}