How is her heart rate? Is it fast?
I'd think the next thing to consider is if she has hyperthyroidism, despite her numbers being in range. Btw, hyperthyroidism can cause polyuria.
Her low MPV (mean platelet volume) is probably not significant at this point.
Regular Iodized table salt is what we use, and I know I never used sea salt at all. T4 9.4, T4 Free 1.34, and TSH 1.900. That's as of January they haven't checked since. They haven't really diagnosed anything with her nor really treated her for anything related to this it's always been watch her and come back if it gets worse. I have to correct myself on some of her labs. Eo% has been at 3 and 4 %, Monocytes are around 6, Neutrophils are 57, and lymphocytes are 34. Her MVP has also been borde borderline low 7.2?! Not sure what that is? She drinks like a horse she's constantly thirsty, and she has told me she is tired all the time. Has complained of frequent headaches, and just watching her play with the other kids she does tire out more quickly than the others. Not sure if that helps anything or is relevant.
anyway, the distinction would be that if she didn't get the goiter from lack of iodine, then you'd have to think about an autoimmune process going on.
oh, the goiter changes everything... maybe.
Was she having only sea salt? (As you might know, that has no added iodine, and neither does the salt in processed foods. In fact, there has been an increase in babies born with thyroid problems since sea salt became popular and mothers were misled that 'natural' is always better.)
Anyway, since giving iodine worked (and since she received no treatment for autoimmune thyroiditis), we can assume the goiter arose from thyroid deficiency. The thyroid does not always go down completely after that, btw.
How were her most recent thyroid lab tests?
They treated her for a goiter when her neck was really swollen and with that they just had me go to a health store and buy a really expensive multivitamin. The extreme swelling hasn't happened for awhile but she is still complaining of pain in that one area of her neck which is just on the inside of her sternoclydomastoid towards her thyroid side. She does get colds constantly and sinus infections constantly. But she doesn't have a history of fevers. So maybe an infectious disease doctor is the way to go?
Hi, I don't know offhand what the ref ranges are, but if her numbers are only slightly out of range, that'd probably be why they're not stressing that.
As far as malignancy, the one to look at would probably be JMML https://en.wikipedia.org/wiki/Juvenile_myelomonocytic_leukemia
but that is very rare, so therefore unlikely. However, that page also has a differential diagnosis list, which "includes infectious diseases like Epstein-Barr virus, cytomegalovirus, human herpesvirus 6, histoplasma, mycobacteria, and toxoplasma". I'd guess they're focusing on histoplasmosis because of the breathing involvement and also on wherever you live.
As a different example, even flu could also cause monocytosis, lymphopenia and the breathing problems, (http://www.ncbi.nlm.nih.gov/pubmed/20133186) but then wouldn't last so long. (Not everyone gets fever, anyway.) So that list includes instead long lasting viruses.
When you say "They treated her for it", what treatment was that?
One possibility that occurs to me is that she might have some lymphocyte immunodeficiency, and everything else comes secondary to that - she gets infections, monocytes increase, nodes swell etc. E.g.: https://en.wikipedia.org/wiki/Idiopathic_CD4-Positive
but that's also rare.
Good luck.