An elderly male w/ history of MCD on chronic cyclosporine with good response, presents with subacute weakness and fatigue found to have AKI (Cr to 7 up from ~2.5). Initially the cause of AKI was unclear and he was given gentle fluids overnight; it now seems that the etiology is relapse of MCD + Cyclosporine toxicity.
When do you give bicarb for metabolic acidosis in renal failure?
*The treatment of severe acute metabolic acidosis is controversial; though there are some concerns about myocardial depression and vasodilatory collapse at extreme low pHs, the data in human subjects is poor. Overall, most clinicians consider initiating treatment of metabolic acidosis when pH < 7.1.
*Because bicarb is actually converted to CO2, use caution about giving this when acidosis is severe. In these cases, and in cases when you must avoid a sodium load, you can consider using THAM (tromethamine) as an alternative buffer. THAM cannot be used in renal failure.
*Bicarbonate supplementation is recommended for all patients with CKD + metabolic acidosis to maintain a goal bicarb of >22. This is based on RCTs showing benefits in terms of a) progression of CKD, b) bone health, and c) nutritional status. See below for one of the landmark trials of this published in 2009.