What Causes Low IGF-1 Levels In Blood?
I recently got my results from my doctor and it looks as though it came up with some abnormalities. I had pituitary tumor(Cushing disease) in 2014. I get tested every year for this. My MRI came out clear but my IGF-1 was low for my blood results. IGF-1 was 138 (normal range 155-432). I just did a 24 hour urinary cortisol test and I'm waiting for the results.
1) what could this be caused by
2) what is the treatment for this
IGF-1
Detailed Answer:
Low IGF1 is not a reliable indicator of a problem. IGF1 levels in the blood are an indirect reflection of the GH (Growth Hormone) status of the body. GH is made by the pituitary and instructs the liver to make IGF1 which then in-turn effectuates the actions of GH on all body cells.
When GH excess is suspected in cases like yours who have a pituitary tumor history, IGF1 is typically checked to look for an excess problem. So if OGF1 is high then one proceeds further to perform confirmatory testing for GH excess. The medical term for this condition is Acromegaly.
However if IGF1 is low, one is unable to derive useful information from this.If GH deficiency needs to be ruled out, then there are better tests that must be performed such as the 'GH Stimulation dynamic / provocative testing protocols' with various medical agents like Arginine.
Endocrinologists are best qualified to evaluate these situations as they can be fairly complex to interpret and manage.
Also if my IGF-1 is low and my doctor has ruled out that its not from a tumor reocurrence, then what is the treatment?
Follow up
Detailed Answer:
I reiterate that you cannot reliably diagnose GH deficiency based on low OGF 1 for the reasons explained in the first response.
Had it been high, it would signal the likelihood of Acromegaly and further testing would need to be performed to confirm the diagnosis. This would also indicate that the tumor was the likely source of GH.
Discuss with your doctor about GH deficiency and whether further testing is warranted for this, based on a thorough physical examination and history.