low GFR

Tuesday i went and got my blood work done and my creatinine level was 1.3 and my GFR was 89 and then sunday i had more blood work done and my creatinine level was 1.8 and my gfr was 48. Tuesday i wasn't on medication but on sunday when i recieved the second test i had been on 800mg bactrim, twice a day for 4 days. Could the bactrim have effected my test results? Four days seems preety fast for my kidneys to go from normal to bad. Some please help me by answering this question.

Thank You

[yorba2]

GFR rate of change is usually pretty insensitive to changes in kidney function i.e it takes a relatively long time for it to show poor kidney function from previously normal this is because the creatine value is an over estimate and the BUN is an under estimate... but a doctor's advice would be better about that.

Since your GFR has changed so quickly its definitely a cause for concern.

[warney]

a drop of over 5 in a year is cause for monitoring, to drop like that in a few days suggests drug interaction or other. i have dropped 37 in 8 months whi,ch is considered extreme, however this was measured over several tests. Ie the trend was a steady, if not rapid, decline. I do suggest that you have it repeated though, just to be on the safe side