Elevated B12 with lack of appetite

[MissSer]

My son is now 10.5yrs. The history is long but about 6months old he stopped gaining weight. He continued to decline & slip milestones. We went to every specialist from Neuro to Cardio to GI to Endo. We finally found a GI that realized even though we had no idea why he wouldn't eat, he needed the nutrition (we had tried supplemental dieting and polycose etc) & so put in a feeding tube. Over the years he's been tested for everything thinkable. We’ve taught him his need to eat even though he doesn't "feel like" he's hungry. Tube was removed. He's been researched from Kennedy Krieger to NIH & remains a medical enigma. The ONLY consistent result that seems like it "might" be a factor is extraordinarily high B12 levels (in the 1900 range & above). I had once read a study that elevated B12 creates an endorphin-like state so he "feels full" & satiated &  has plenty of energy. We finally stopped testing him a few years ago as there seemed no answer & we were managing with behavior mod. He is an "A" student, has no behavioral problems at school or home, great disposition, loves sports, never even gets a cold, had a full genetic testing workup  & disease testing (from celiac to familia autodysnomia) . He's been scanned, explored and biopsied He's just very small. We stopped tracking the standard charts long ago and were satisfied as long as he kept on his own curve. Recently he fell off his own curve and this is concerning. He's. A few questions: Have you every heard of elevated B12? What can I expect when he's supposed to hit puberty? Insurance won't pay for growth hormone because we did the study and his levels are completely normal - ideas? Anything I should consider?

I don't expect a magic pill, "cure" or diagnosis but I do want to keep him healthy in body & mind & so truly want to explore the Growth Hormone treatments but I'm getting resistance as his chemistry doesn't show deficiency.

Any assistance would be appreciated. Thanks ~Serena