I have addressed variations in urine Gd content in an earlier blog. This is an expansion.I think that there may be daily variations on Gd elimination (termed diurnal), and co-existent additional cycles that are much longer, are also occurring. I had previously mentioned, over the menstrual cycle this is likely occurring. Not previously mentioned is seasonal. Symptoms may be worse in the fall and winter, because there is less native sweating, and also less general activity. Less salutary effects of vit D from sun exposure, as well.Periods of hormone change: puberty, menopause, also very important stimulating effects.The main reason I like 24 hr urine Gd collection for determining Gd presence, is because there is likely variation through the course of the day with the amount of Gd eliminated. In part this may reflect that day time physical activity may result in more Gd release from bone and muscle, which results in more Gd release at that time. One physician recently observed to me, that with EDTA they can use 6 hr urine Gd, and this is more preferable than 24 hr urine that DTPA 'requires'. The reality is neither chelator requires any particular time of collection - my opinion is that 24 hour collection is more informative.One could at the same time ask, since I downplay any absolute importance to urine Gd (to make the diagnosis of GDD for example) why then make collection more rigorous. My primary explanation is in the earliest stage of disease recognition, diagnosis and treatment it makes sense to be more accurate with any measurement, especially if it does not cause excess or undue hardship or cost. I suspect as long as it is standardized, such as routinely using first morning spot urine, this may actually be sufficiently accurate for most purposes. But I would like to study this first. So does EDTA get away with 6 hr urine testing and DTPA require onerous 24 hr urine collection. No for both, more accurate is obviously 24 hr, ok is 6 hr, and probably sufficient, provided it is standardized to the same 6 hr period. The best therefore of short acquisition urine may be first morning... but this would ignore the effect of physical activity in the day time to release more Gd from bone and muscle for elimination. But it would be standardized, which is likely the most important property of all tests - that they are standardized and hence more reliably comparable.Regarding response to chelation treatment, sufferers focus on urine Gd content as a primary indicator. The best indicator is how you are feeling on a weekly basis as you move farther away from chelation. If you are feeling better, then that is the main basis to think chelation is working. I do however value the information of the native urine elimination, and also the amount of increased Gd urine content of elimination. But I focus of the importance of these metrics at specific times through the course of treatment. More on this in a later blog. Native Gd is always useful and that is why I never would do provocative urine Gd without knowing the native level immediately before provocation. To repeat what I have written before. The best provocative agent is Ca-DTPA . Regarding other chelators, some are frankly worthless. I do not like DMSA for example as a provocative agent. It does not remove enough Gd to be useful for the determinations I am looking for.Richard Semelka MD Consulting
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