RE: High IGF-1

[Guest guest]

The first suspect for high IGF-1 is the pituitary gland. When my levels started climbing, from the high 200's to over 400 with lab ranges usually around 43-270, Dr. Vivian (in Houston) began testing both IGF-1 and GH (Growth Hormone). Growth Hormone levels are very transient in the body so most times my levels of GH were normal. According to many articles I've read, this is very common in about 1/3 of patients. IGF-1 is the long term marker of GH, similar to what the A1C is for diabetics, which measures long term blood sugar levels.

So, usually what a doctor will do is order a GTT (Glucose Tolerance Test) of at least 3 hours. You fast for this, then they give you the sugary drink, test GTT, GH and IGF-1, then test them again on the hour for 3 hours. If GH (and IGF-1 levels ) are suppressed during the test, then it tells the doc whether the pituitary is the culprit. In my case it was supressed, which told her that most likely it's not the pituitary.

Dr. R. does the test differently that most docs. Most of them will just do one IGF-1 blood test at the beginning, she orders one each hour. Despite what some of the lab sites say, Dr. R. assured me it gives her more info and indeed she was ABSOLUTELY right. BOTH the GH and IGF-1 were supressed during the test. I will tell you, though, it took 4 tries at this test and finally I had it done in Dr. R.'s office because the various labs forgot or ignored the orders to do all 4 time line (GTT, GH, IGF-1) samples; baseline and 3 more on the hour.

That being said, if it's not the pituitary then there is great confusion about what to do next. It would seem likely to test GHRH (Growth Hormone Releasing Hormone) to see if it's a hypothalamus problem, but there doesn't seem to be a single lab in the U.S. that actually tests it and we've tried and tried to find one. We've even contacted various Acromegaly organizations who have also tried to find one to no avail. There can be tumors in other areas of the body that can spike GH and hence IGF-1 but I'm still not sure how they find them. Perhaps an octreotide scan but I'm not sure yet. The scan is where you get injected with the radioactive dye one morning, then come back the next day for a full body scan. What I don't know is if it can pinpoint these KINDS of tumors. I do know the scan is designed to find excess SERATONIN producing tumors. But, we didn't get that far in the process.

The really surprising thing is that this LAST test, which was done a week ago, showed my IGF-1 was at 220, the lowest it's been since we've been measuring it and well within normal range according to Dr. R and my surgeon Dr. Baskin. No one knows why it's down (maybe it's all the prayer that we've been doing!!!!) but I'm grateful for this! I'm also praying for a miracle,,,,,that this pituitary tumor has shrunk (or is it shrank???) and I won't have to have surgery.

And to answer your question; I'm personally not aware of any connection of low T3 and high GH. From what I understand, if there is a pituitary tumor it usually INCREASES certain hormones including GH, thyroid and female hormones, not decreases them.

To: Texas_Thyroid_Groups From: christineshreve@...Date: Mon, 4 Oct 2010 23:38:01 -0500Subject: High IGF-1

Someone mentioned they have high IGF-1. My dd was tested with this last week. Her t3 is very low, as well. I’m told the two are not connected. Did your doc figure out why your IGF is high? We have 2 endo appts for this, hoping one can explain it to me. My expectations are low, given the cluelessness I’ve recently encountered among this specialty.Any comments are appreciated.