We prescribe them with abandon to our CKD and ESRD patients…Nephrocaps, Renavit, whatever you want to call it. How many nephrologists do you think are able to name all the ingredients in this vitamin-containing tablet?
The not-so-secret ingredients: nephrocaps consist of vitamins B1 (thiamine), B2 (riboflavin), B6, B12, folic acid, niacin, pantothenic acid, biotin, and a small dose of vitamin C.
You will note that these are all water-soluble vitamins. The fat-soluble vitamins (A,D,E, & K) are generally not a problem in ESRD patients (with the obvious exception of vitamin D, whose activated form is produced in the kidney) as the body has adequate stores of these and in fact supplementation with vitamin A, for instance, can cause toxicity. ESRD patients are often deficient in water-soluble vitamins for a number of reasons: poor oral intake, restricted protein diet, and the fact that many of these are dialyzed off during treatment. Nephrocaps are designed with these losses in mind.
I am a geriatrician. I just saw an 80 yo patient referred to be for a gait problem. He has a serum creatinine of about 1.5, GFR of 45 mL/min – he has been on Nephrocaps for years! He is obviously not on dialysis. He has developed a gait disorder and peripheral neuropathy. His pyridoxine level is 90 ng/mL! (normal range is 2 to 22 ng/mL in our lab) I think he may well have pyridoxine toxicity.
Just posted a blog entry about this. See http://pbfluids.blogspot.com/2008/11/renal-vitamins.html