Hi Trav -
These things aren't necessarily Lyme related. One of the functions of your kidneys is regulate blood sodium and potassium (electrolytes). The kidneys are capable of conserving these over a wide range of conditions - so sometimes low Na or K doesn't show up until the underlying condition is more severe.
Diuretics (like I take for BP) and drinking too much water can cause too much Na to be removed. Since you're not drinking an excessive amout of water (hmm ... coffee, tea, and caffeine are also diuretics), it may be an indication your kidneys are not functioning optimally.
I know when my Na got down to 128 mmol/DL, I felt pretty bad. When it didn't pop back up after cutting down the diuretic, I went to a Nephrologist.
I now maintain Na anc Cl at the low end of the normal range. I've also gotten away from the really tight salt control I was doing for my BP.
If your Na is much below 135, it should be discussed with a Dr or ARNP (doesn't need to be LLMD). It wouldn't hurt to cut out any coffee, tea or caffeine in the mean time.
Hope this helps.
Lyme, anxitey, depression, chronic C. Pnuemoniae
"... expect the unexpected ..." (O. Wilde)
"I am an old man and have known a great many troubles, but most of them never happened." (Mark Twain)