For over two years I was successfully treated with HAART a. Without warning I came down with lactic acidosis (the blood chemistry showed it but I felt fine) and hypothyroidism. After a 2 month STI I was switched to a new regimen. Now, after only 2 months I have once again gone into lactic acidosis but still feel fine. How can I isolate what is causing this? How common does this occur on HAART? Is there something I can do to treat acidosis so that I can continue HAART? I feel like I am quickly running out of options.

You don't discuss which drug cocktail you were on. In most cases the main offending drug has been one of the nucleoside reverse transcriptase inhibitors (nukes) most commonly D4T, 3TC, AZT, and ddI. Often a good cocktail can be constructed switching the nuke drug around (such as from D4T to AZT or abacavir) while sticking with drugs from other classes (ie the protease inhibitors and non-nucleoside drugs). Also, a lower dose of the offending drug sometimes works. It is unusual not to be able to come up with another good drug cocktail (leaving out the offending drug) that will still work OK so don't get discouraged. What can be used is highly dependent on your past drug/treatment history. Most experienced HIV providers are becoming well versed at handling this situation. It is believed that mitochondrial toxicity plays a role in this so some believe that supplements like co-enzyme Q, L-carnitine, B1/B2 vitamins, and N-acetyl cysteine could provide some protection but that is unproven. I have numerous patients in my own clinic where that has happened and the vast majority are still doing well. Keith Henry, M.D.