I will only comment on number 2. You wrote:
""2. SUBCLINICAL MASTITIS

Subclinical mastitis, defined as raised milk sodium/potassium (Na/K) in the
absence of clinical symptoms. Therefore, I would not know one of my clients
has subclinical mastitis unless I did a milk analysis. When would I do
this, if ever? I´ve read it is associated with poor infant weight gain and
increased risk of mother-to-child HIV transmission. I have no HIV mothers
in my practice. QUESTION 2: Would subclinical mastitis be a cause of FTT in
the child of a
healthy mother? Should I be looking out for it?""

I would not see the value in monitoring for this, unless you are monitoring
an HIV positive mother, or a mother who is prone to frequent mastitis and
if there was something she could do when the electrolyte levels rose. Of
note, Na levels rise during weaning as well, right? How would that
complicate the picture, or is it that the mother is experiencing milk
stasis (poor drainage of breasts, infrequent emptying of breasts) and
therefore unintended weaning (supply going down)?
As far as being associated with poor infant gain, I link it back to poor
drainage of the breast and/or infrequent emptying (infrequent feeding)
leading to a dwindling supply. The saying  "what came first, the chicken or
the egg?" seems to apply here.
Laurie Wheeler RN MN IBCLC
MISSISSIPPI USA

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