Q: I am a 37 years old male had nephrectomy for renal cell carcinoma (RCC) last year. It was in localised state. Now, I live with single kidney. I am regularly checking my serum creatinine level for last consecutive two months. My latest serum creatinine level is 1.55. Is my serum creatinine level normal? If not, how can it be managed?

A:An individual normally has two kidneys. And, when one kidney is surgically removed due to cancer, the overall kidney function is reduced proportionately in the immediate post-operative period. For example, if both kidneys were contributing equally to the overall kidney function initially, removal of one kidney reduces overall kidney function to about half of its pre-surgery value. However, the remainig kidney soon begins to compensate for this loss in overall kidney function. Studies have shown that there is a 30-50% increase in the function of the remaining kidney as early as 1-2 weeks after the surgery. In approximately a third of patients, overtime, this additional burden and co-existing medical problems can eventually lead to progressive kidney damage in the remaining kidney. Older age, female gender, lower baseline kidney function prior to the surgery, injury to the remaining kidney during or in the immediate post-surgery period and co-existing medical diseases such as diabetes and hypertension increase the risk of damage in the remaining kidney over the years. Creatinine is a break-down product of muscle and is filtered out of the blood into the urine by the kidney and removed from the body. Therefore, when kidney function worsens, less creatinine is filtered out of the blood and creatinine blood levels rise. Hence, blood creatinine levels are used to monitor kidney function. A blood creatinine level is also used to estimate the glomerular filtration rate (GFR) which is a measure of the kidney filtration function. Normal GFR is around 100-130 ml/minute/1.73m2. You have indicated that your blood creatinine level was 1.55 mg/dl, five months after your right kidney was removed surgically. This corresponds to a GFR or 51 ml/minute/1.73m2 (calculated using MDRD formula which also takes into account your age and race) which suggests that your kidney function is significantly less than normal. You also mentioned that the creatinine level was the same in the previous month also. This suggests that your kidney function has been relatively stable (but lower than normal) over the last month or so. However, since you have not provided me with your creatinine levels prior to and immediately after the surgery, I cannot comment on the effect of the surgery on your kidney function or on how well the remaining kidney is compensating. Regardless, your recent blood test results indicate stage 3 (moderately severe) chronic kidney disease and you need an in-person evaluation and close follow-up with a nephrologist. You will need additional tests to evaluate the cause of the kidney impairment, including urine tests to see if there is protein and/or blood in your urine. It is also essential that you maintain strict control of your blood pressure, diabetes, high cholesterol (if any) to prevent further deterioration in your kidney function. You should also avoid non-steroidal anti-inflammatory drugs (NSAIDS) such as ibuprofen, naproxen and indomethacin, as they can be harmful to the kidney. Finally, It is also generally recommended that individuals with only one kidney avoid heavy contact sports, such as boxing and martial arts, to protect the kidney from inadvertant injury.