Creatinine going down (1.45 to 1.35 in 10 days), but Potassium 5.5?

[Ijxyz]

Hi all,

Recently, during an initial blood check my Creatinine was 1.45 (GFR 64). After 10 days of keeping on top of the water (4l), reducing protein (from 180-200g to 50-70g) my Creatinine dropped to 1.35.

I can see creatinine levels can depend on lifestyle, diet and physical activity. I am 25. I am white race, 6' 2" 210lbs. My BSA area is 2.20m2. Fairly muscular with years of weights training experience 5x a week. No steroids. No creatine for the last few months - just training approx total 9-10 hours a week.

My urine was tested alongside the second blood test. There was trace protein, however it was within the normal minimum range of protein found in routine spot urine checks. GP described urine tests as fine. Therefore, it wasn't "1+". Urine Protein:Creatinine is also ok.

I dealt with two different GPs after each blood test. The second GP didn't even mention the Potassium 5.5 despite it being right next to Creatinine and GFR. I saw it myself after seeing the print out. The first GP said all results were fine except of Creatinine and GFR - is it possible Potassium wasn't then tested?

1. Is it common for Creatinine levels to drop that much within 10 days of just reducing protein and not working out?

2. Would Potassium be tested in the most basic blood tests? I.e. my first one.

3. The nurse made me clench my first when drawing blood. How common is this to give false results of elevated Potassium?

The GP told me to keep protein 'normal' and re-check in two months. I intend to continue not working out, keeping protein below 70g and now also keep potassium below 2000mg. I'm looking to redo the bloods in 2-3 weeks.

Any advise and thoughts would be much appreciated. Is it to early to worry, but just stay on top of it?

[MAS_Nurse]

Hello ljxyz

Thank you for your message. You seem to be very knowledgeable about your situation and you are right to be advised by your GP to have another blood test in 2-3 weeks.

To answer one of your questions , potassium levels may not have been tested in a basic level test unless your GP specifically requested this test. You may want to check with your doctor.

Clenching your fist will most likely not make a significant difference to your results, but having the repeat test will help you to see any differences in results.

Keep on with your regime maybe within moderation and let us know how you get on.

Members please give ljxyz some information and support.

Www.kidneyresearchuk.org may have more information

Best wishes

[Ijxyz in reply to MAS_Nurse]

Thank you for your response. Does the GFR 64 to 72 seem like a big jump over ten days? Perhaps the muscle mass, protein diet and gym played a part and having 10 days off influenced the GFR? Is there a possibility that this GFR has got further up considering I continued low protein, high water and no working out (just daily walking) and the original reading was understated?

GP advised 2 months and didn't even mention Potassium. However, I will try to do it over the next two weeks.

[Jonquiljo in reply to Ijxyz]

The protein diet is probably raising creatinine (and therefore lowering GFR) substantially. You also have a LOT of body muscle mass. Most of the GFR equations to NOT take into account someone's body mass when looking at GFR and possible CKD. If your GFR was calculated with a formula that takes your body mass into account - it probably is a whole lot higher.

Just the amount of protein you ingest alone is enough to raise your creatinine levels and give you a false-low GFR.

I assume the protein that you are ingesting is from a mix and not just eating a lot of food with protein. If so, could the potassium come from a protein supplement or something like that? You've got to be careful about any of these bodybuilding supplements - as they are not regulated and rarely checked out. Good luck.