are her kidneys normal??

[jenn096]

occasionally my sister has a problem with her kidneys.. if she doesn't drink much water for a few days she starts peeing drops of blood and it's really painful...  that's what she says.. it's just because of the water and if she drinks a lot she is ok..i mean if it was a bladder infection she wouldn't be ok just with water i guess..  but how is this normal? i haven't heard anyone peeing blood just because they dont drink much water..  what do you think??  she's 24