Protein in the urine is medically referred to as "proteinuria". As we had discussed earlier, abnormally high amount of protein in the urine is one of the hallmarks of Chronic Kidney Disease (CKD). We also talked about the role of moderate protein diet in preventing CKD progression. But if protein in the urine is just another downstream effect of kidney disease, then why do we nephrologists make so much fuss about treating it?
Well, herein lies a key concept that I am going to talk about today. Which is that protein is not just another consequence of CKD, it actually directly makes kidney disease worse. Which leads to further kidney damage; and which leads to even more protein in the urine! So it might start off as an effect, but it soon becomes (part of) the cause as well. I guess you are getting my point. Protein is not just a sign of the problem, it is the problem!
Let us look at the evidence to support the above conclusion. A lot of research has been done on this, and today, minimizing proteinuria is a valid "target" for retarding the progression of CKD.
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A key factor in the progression of kidney disease (regardless of the cause) is elevated pressure inside the kidney's filtration system. This is called intraglomerular hypertension. This leads to elevated filtration rate, or GFR, in the initial stages of kidney disease. Over the short term, this might help the kidney numbers "look pretty". In the long run, it is actually maladaptive and GFR drops, and is the reason for scar tissue formation is many kinds of CKD, eg. diabetic kidney disease.
Protein in the urine makes intraglomerular hypertension worse. And so we have medical evidence that indicates that untreated proteinuria significantly increases the chances of your kidney disease progressing to failure (when dialysis or transplantation become necessary). The level of protein in the urine is directly proportional to the risk of your kidney disease getting worse. Similarly, multiple medical studies have proved that worsening of kidney disease can be prevented if proteinuria is treated using specific drugs like ACE inhibitors or ARBs. Interestingly, the protective effect that comes with these medications is independent of the control in blood pressure induced by the drugs! A greater reduction translates in to more kidney protection, and a more favorable outcome for your kidneys.
THINK BEYOND THE KIDNEYS
Excess protein in the urine does not just portend bad news for your kidneys. In fact, now it is also known to be a big risk factor for developing cardiovascular disease, putting you at risk of heart attacks, strokes, etc.
WHAT HAPPENS IF YOU DON'T TREAT PROTEINURIA WITH THE ATTENTION THAT IT DESERVES?
As mentioned above, untreated proteinuria makes you lose GFR faster, and worsens kidney disease. But just how bad is it? Well, there was a time when the renal prognosis for patients with proteinuria (for instance, from diseases like diabetes), was considered benign. However, this notion has long been dispelled, and now epidemiological evidence has given us some objective data. We now know that, left untreated, severe proteinuria will cause end stage kidney disease (requiring dialysis/transplantation) in diseases like diabetes, in as little as six to seven years!
Veeraish "VC" Chauhan, MD, FACP, FASN
Bradenton / Sarasota / Lakewood Ranch, FL