If your doctor says your kidneys are not working 100% … is that a problem? ABSOLUTELY! You need your kidneys in order to stay alive and when blood tests begin to show kidney problems it means you have lost a lot of kidney function already — at least 50%. So, the wise doctor and the informed patient need to run a checklist to do the right things. If you wait until you have symptoms of complete kidney failure, it’s too late.
The main blood test for kidney function is serum creatinine — abbreviated Cr. The kidneys have a large reserve capacity; in fact, a person can donate a kidney and still have the creatinine (Cr) blood test be “within normal limits”.
Many things can go wrong with the kidneys that range from the fairly simple to the terribly complex. For instance, kidneys can be damaged simply by the bad effects of high blood pressure or by esoteric autoimmune diseases (“friendly fire” where the body’s defense against germs is accidentally directed at healthy kidney tissue).
You need to know 4 things to estimate your kidney function:
- Serum Creatinine (Cr) as measured on a blood sample.
- Your age (in years)
- Your race (black or not-black)
- Your gender (male or female)
Then you calculate another number called eGFR (estimated glomelular filtration rate) based on the items 1 – 4. Often, this is automatically calculated by the lab — if not get the answer from many online web sites like the National Kidney Foundation eGFR calculator. The normal value is 100 but it’s not considered abnormal until it is below 90.
|STAGE||eGFR||DESCRIPTION||TREATMENT (also see tables below)|
|1||90+||Normal kidney function but urine findings or structural abnormalities or genetic traits point to kidney disease.||Observation, control of blood pressure.|
|2||60-89||Mildly reduced kidney function, and other findings (as for stage 1) point to kidney disease||Observation, control of blood pressure and risk factors.|
|Moderately reduced kidney function||Observation, control of blood pressure and risk factors.|
|4||15-29||Severely reduced kidney function||Planning for endstage renal failure.|
|5||below 15 or on dialysis||Very severe, or endstage kidney failure (sometimes called established renal failure)||Dialysis or transplant.|
Now to the checklist mentioned above (Clin J Am Soc Nephrol 9:1526-1535,2014.): All is well if you have no known kidney problems, the eGFR is above 90, the urinalysis (U/A) is normal, and you have no genetic predisposition to kidney disease (like a family history of polycystic kidney disease). Otherwise, you have stage 1-4 kidney disease so check off the items below to make sure important tests and treatments are obtained.
Slow the progression.
Find and treat complications.
|Check hemoglobin and Iron — keep in satisfactory range.|
|Check calcium, phosphate and PTH — keep in satisfactory range.|
Referral to nephrologist.
So, this seems complicated? TRUE. That is precisely why a checklist is needed. And, that is why the informed patient needs to go over this checklist with the primary care provider. Print a copy of this post and take it with you to an appointment to start the discussion.