Ferritin tests are affected by many things and small fluctuations should be no cause for concern. Christian's level remains in an acceptable range and the variation between tests hasn't been anything unusual. The follwoing article states some of the factors that can influence ferritin tests.
From
http://www.charite.de/ch/medgen/eumedis/thalassemia04/monitoring-iron-chelation.htmlSerum ferritin: it is the most widely used parameter to quantify the iron overload; unfortunately many factors independent from iron stores, as infection, inflammation, hepatitis, hemolysis, vitamin C deficiency may alter significantly the serum ferritin concentration.
Ferritin testing is used to monitor iron levels but are not considered to be completely accurate. Tests such as liver biopsy, MRI, SQUID and Ferriscan analysis of MRI's are used to give a much more accurate measure of actual iron stores, rather than testing blood serum. While ferritin testing is used to measure progress or lack of progress, it is not intended to be the ultimate measure of iron stores. Changes in the 100's between tests are common and should be no cause for alarm. At some point, Christian will have one of these other tests and you will have a much better idea about his situation. These tests will be done regularly (possibly annually) and will give a much better picture of his long term iron stores. Keep in mind that iron in blood serum poses no danger. It is the stored iron that causes damage to the organs and tissue.
My feeling on these results is that Christian continues to show that his iron levels are not increasing and at his age, this shows that the chelation is doing a good job regulating iron in his body. Many parents of young children have problems maintaining ferritin below 2000, largely because of different chelation issues, such as minor reactions to desferal, or simply wanting to give a child a break from the needle, or even trouble establishing the proper dosage. In my opinion, considering Christian's age, he is doing quite well in maintaining a low, acceptable ferritin level.