RT Journal A1 Hamilton RW T1 EXacerbation of renal failure with doxycycline use-reply JF Archives of Internal Medicine JO Archives of Internal Medicine YR 1979 FD May 1 VO 139 IS 5 SP 604 OP 604 DO 10.1001/archinte.1979.03630420089034 UL http://dx.doi.org/10.1001/archinte.1979.03630420089034 AB In Reply.—  My colleagues and I agree with Dr Whelton's comments regarding the difficulty in drawing firm conclusions about pathogenesis of renal failure on the basis of a single case. Analyses of drug concentrations would have made a stronger case, but these are not generally available.However, we take issue with Dr Whelton's comments regarding the disparity of BUN and creatinine concentrations in our patient. It is true that the quotient of BUN/creatinine generally exceeds 10 in patients with tetracycline nephropathy. We reviewed the articles by Shils1 and Phillips et al2 with regard to this quotient. From the data presented in these articles, a mean BUN/creatinine quotient can be calculated. For the data from Shils, the quotient was 17.9; for that from Phillips et al, it was 12.1. The peak BUN/creatinine quotient in our patient was 18.0. We submit that this is consistent with previously reported cases of