What are the signs and symptoms of CKD?

I see a lot of patients in consultation in my clinic who are, well, not quite sure why they are in my clinic! Usually, they would have been referred from their primary physician because they were deemed to have "chronic kidney disease, or CKD". A frequent refrain is, "Doc, I feel fine. I don't know why they asked me to see you?!" 

The reality is that CKD belongs to that dreaded class of diseases called, "the silent killers". In other words, you may or may not have any symptoms! In the early stages especially, the only abnormality might be elevated creatinine or reduced GFR when your physician checks your kidney function. Some common misconceptions regarding kidney disease are that the kidneys "should hurt", or you "stop making urine". These are nothing more than medical myths.
There certainly are kidney disease conditions that can cause pain, like kidney infections (pyelonephritis), or kidney stones. However, medical kidney disease due to something like hypertension or diabetes may not cause you to feel any pain. Similarly, you could continue to produce urine even in advanced stage 5 CKD. I see dialysis patients who make a liter of urine daily. This is not surprising if you realize that the kidneys filter almost 1440 liters, or 380 gallons, of blood everyday. Even if your GFR is 1, it could mean that your kidneys are still filtering about 10-14 liters of blood daily. It is not hard to imagine that the kidneys can still produce a liter of urine from this 10 liter of daily blood flow. 

As kidney disease worsens from stage 1 thru 5, other not-so-subtle abnormalities can begin to develop. These include:

• Your blood pressure may begin to increase. This is because you tend to build up fluid and salt in your body (which normal kidneys do a better job of getting rid of). The kidneys could also produce excess amount of certain hormones called renin and angiotensin that increase blood pressure. The built up fluid/salt may manifest as swelling, or edema; or fluid accumulation in the belly (ascites) or around the lungs (effusion). 
• Acid level in the blood can increase. This is because it is the kidneys that get rid of excess acid that you eat, or the acid that the body creates from breakdown of other metabolites. This excess acid can then have deleterious consequences for your heart muscle or nerve function, and cause calcium to leach out of the bones (thus increasing your risk for fractures).
• Potassium level in the blood can build up as well. High potassium can in turn cause symptoms ranging from muscle weakness to abnormal heart rhythm. 
• Normally, the kidneys also produce a hormone called erythropoietin (yes, the same hormone that a certain professional cyclist was accused of doping with!). This hormone is crucial in the production of red blood cells. Patients with CKD could hence have anemia, or low red blood cell counts, leading to fatigue, failure to thrive, and in severe cases, heart failure. 
• Elevated phosphorus levels in the blood can be seen. This could then lead to elevated production of another hormone called PTH (parathyroid hormone) by the parathyroid glands. High PTH levels, along with low vitamin D levels that can also be seen in CKD, can increase the risk of bone disease and fractures. This is referred to in medical terms as "CKD related mineral and bone disorder (CKD-MBD)". 
• Urea level in the blood can be extremely high in advanced CKD. Patients at this stage can have a constellation of symptoms that include fatigue, lethargy, nausea, chest pain, shortness of breath, difficulty falling asleep, decreased appetite or a metallic taste in the mouth, etc. This is referred to as "uremia". 

Needless to say, patients may have some, or none of the above signs and symptoms. Which is why you need to consult with your nephrologist to determine an appropriate treatment plan regardless of how you feel!