Interesting - I am metal intoxicated and also had a Metametrix GI-Effects done and I, too, have an extremely low pancreatic elastase reading.
I also know I have some serious biliary and liver issues, but I suspect these have arisen as a consequence of the heavy metal intoxication, since heavy metals such as mercury are generally excreted via the biliary route (unless one is consuming a chelation substance such as DMSA). This propensity to excrete via the biliary route not only stresses the biliary system, but also means the liver has an impossibly hard time, added to which, the many liver enzymes are incapacitated by mercurys ability to displace other minerals such as selenium - these minerals are vital catalysts for these enzymes s once they've been displaced by/with mercury, they can't function and the liver has yet more toxicity to cope with which it is unable to disarm. Many folks who've experienced this scenario then find they have an increasing number of food sensitivities and consequent immune-related bowel inflammation (certain food chemicals which are harmless to a healthy human being becomes toxic to a person whose liver is unable to metabolise/detoxify them appropriately).
Note that the stress on the biliary system means that bile quality can become compromised and when that happens, the potential for formation of stones may be increased. In the event of this perhaps occurring, it is theoretically possible for bile flow to become restricted, both as a consequence of the exit of the gallbladder becoming partially obscured and as a consequence of the gallbladder as a whole becoming impeded in its attempts to contract when bile secretion is required.
The pancreas relies upon correct pH signaling in order to secrete appropriate enzymes. In a scenario whereby bile flow is compromised, this may have a knock-on effect because the pancreas secretes bicarbonates into the bile and insufficient bile flow may also compromise transit of bicarbonates. Thus, pH signaling can become compromised, too, with the result that the wrong enzymes may be excreted for the purposes of digesting particular types of foods. Additionally, foods which had necessitated the secretion of high levels of stomach acid, during their transit through the stomach, will result in a highly-acidic chyme being passed through the pyloric sphincter which needs plenty of pancreatic bicarbonates to be released (at the sphincter of oddi) in order to neutralise the chymes acidity prior to entering the duodenum. Failure to sufficiently neutralise the chyme can result in acid damage to the epithelial lining of the duodenum and, potentially, even the bowel.
Further still, the release of insufficient and/or incorrect, enzymes (due to impedance of bile flow and/or insufficient bicarbonate release and/or insufficient bicarbonate transit within the bile) can result in food particles being incompletely digested, and this is another way in which food sensitivities can develop, as the immune system may interpret such food particles as being foreign and thus requiring immune response, one major tactic of the immune system (particularly when chronically stressed) being inflammation (e.g. bowel, and possibly even systemically, in serious cases).
Also of note is the fact that mercury can interfere with the function of the endocrine system. Note that the pancreas operates partly as an exocrine organ and partly as an endocrine organ.
Something to think about?
I would recommend you and your children:
1) STAY AWAY FROM CILANTRO / NDF at ALL costs! It is widely recommended in alternative health circles (even by many so-called 'experts' on the topic of heavy metals, such as Klinghardt, Kaslow, Mercola, Group, etc.) but the topic of heavy metal detox requires an intimate understanding of molecular chemistry, which these so-called 'experts' clearly lack to a sufficient degree. Cilantro is downright dangerous to someone with heavy metal intoxication because it can facilitate the migration of heavy metals from existing tissues into the bloodstream and across the blood-brain barrier into the brain. This isn't 'opinion' on my part - it is verifiable fact - the pharmacokinetics of cilantro are NOT yet known, and without this, one cannot chelate safely, no matter how many people claim cilantro is 'safe to chelate with', and no matter how many qualifications or letters they may have after their name. I've personally experienced the dangers of cilantro/NDF myself, too, as someone who is heavy metal intoxicated and undergoing chelation. I will never go near these substances again.
2) Acquaint yourself with the work of Andrew Hall Cutler (http://www.noamalgam.com/ & http://www.noamalgam.com/hairtestbook.html
- the website is a little confusing but the books are absolutely superb and worth every penny and then some). He is someone who DOES have the requisite knowledge of molecular chemistry to enable one to chelate SAFELY (i.e. without damage to the brain and central nervous system due to redistribution of existing body burden of mercury etc.). Cutler was himself mercury intoxicated (from dental amalgams) and chelated himself back to health using a very precise protocol which he developed using his intimate professional knowledge of molecular chemistry.
3) Get yourselves tested using hair analysis, via DirectLabs.com (order the 'Hair Elements' analysis, NOT the 'Toxic Elements' analysis. I know this seems counter-intuitive but please believe me, it is definitely the normal 'Hair Elements' test you want, because it includes almost all the toxic elements AND many non-toxic elements which are vital for determining statistical data patterns - sounds complex but is easily understood because Cutler has done the hard part for us - just see his 'Hair Interpretation' book for explanation).
Your son's yellow skin is, obviously, a very clear sign of compromised liver function, and the constipation, as I'm sure you are well aware, is possibly related to biliary insufficiency (bile serves many functions, one of which is to stimulate bowel peristalsis). If you're not already supplementing with milk thistle, then please consider doing so, unless contra-indicated by your doctor or by something else you are currently doing which I may not be aware of. In itself, milkthistle is a very safe substance, even for folks with heavy metal intoxication. Milkthistle not only protects liver cells to some degree, but it also stimulates secretion of bile - a win-win for the liver and gallbladder.
Please also consider that the reflux he is experiencing might alternatively be related to reflux of bile into the stomach, rather than simply HCL into the oesophagus (not to say that that might not also be occurring). e.g. http://www.mayoclinic.com/health/bile-reflux/DS00651