Chronic kidney disease

Chronic kidney disease is the name given when the kidneys are no longer in good shape — either because their structure has changed or because their work has fallen off — and that has been going on for at least three months and is costing the person their health. Both ways in count equally: there may be visible damage to the organ's structure, or the structure may look acceptable and what's failing is the function. What turns a rough patch for the kidney into chronic disease is that the problem settles in and stays.

To sort it out, the clinical classification doesn't settle for a single piece of information: it looks at three. First, where the damage came from — the cause. Second, how well the kidneys are still filtering the blood, which is the strainer job the kidney does when it separates what stays in the body from what leaves in the urine. And third, how much albumin, a protein that normally travels in the blood, is leaking into the urine. It's like judging a filter on three things at once: what damaged it, how much liquid it can still process, and what is slipping through where it shouldn't.