Low Iron and Endoscopy

I had iron studies done 2/09 due to unusual fatigue.  My levels are as follows.  These were taken 3 days after my period ended.

Serum Iron   32
Ferritin 3
Iron Binding 454
% Saturation 7%

I started iron supplementation and my levels on 4/7/09 have returned to normal.  The labs were taken right before my period began.

Serum Iron  87
Ferritin 16
Iron Binding 361
% Saturation 24%

My hemogloblin has been stable at 12.4.

During my last period, I soaked 7.5 super plus tampons and 3.5 super tampons plus other partially soaked pads and tampons.  My period was 6 days.  This is relatively normal although the volume has probably increased over the years.  I am 40 years old.  

My question:  Do you think the iron deficiency more likely from my period than a GI source.  My family MD has sent me to a GI MD who wants to do a colonoscopy and upper endo.  My stools were heme negative.  I feel that this is a bit of “overkill” and wanted your opinion.  Thanks.