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Kidney Diseases

Creatinine Fluctuation

08/25/2009

Question:

I had a routine blood test performed by my doctor about a month and a half ago. At the time my serum creatinine was elevtaed, 1.6. Just had another round of blood tests to check the previous result, my doctor also requested a renal ultrasound. I thought I might have been dehydrated the first time around. I have hypertension, 146/81 last time i had it checked, just started on one 20mg tablet daily of Lisinopril for my high BP. I adopted a renal diet, in the event that I did have CKD and if I did not have CKD the renal diet would help lower BP (lower protein, salt, etc.). I have lost 18 lbs since then and dropped my BP 8 points naturally i.e. before the Lisinopril was prescribed. My blood work just came back and my creatinine was at 1.16 and my renal ultrasound came back normal. My question is, can diet alone cause me to lower my serum creatinine by that much?

My doctor plans to check my creatinine again in 3 months.

P.S. I am a 28 year old male, 215 lbs, medium build, and up until recently had a high protein diet.

Answer:

It is possible that going from a very high-protein diet (plus dehydration) to a protein-restricted diet could have lowered your creatinine.  However, it is still possible that you have CKD, because even a creatinine of 1.16 is a little high for a 28 year-old -- although if you have a lot of muscle mass, this may actually be a normal creatinine for you.  In this case the best way to determine whether or not you have CKD is to do a 24-hour urine creatinine clearance and urine protein measurement (which can also be done on the same 24-hour sample).  

If I understand correctly, you had not yet started on the lisinopril at the time the 1.6 value was obtained.  However, if you were on lisinopril at that time, the high creatinine may be a tipoff that you have a narrowing of the renal artery(ies), which should be studied by either a CT scan with IV contrast dye, or by an MRI angiogram.  (But if you were not on lisinopril, just ignore this paragraph.) 

In any case, it is unusual for a 28 year old man to have high blood pressure, so be sure to take your meds faithfully, have your cholesterol checked and treated if needed, and DO NOT SMOKE, so as to minimize the possibilities of kidney damage, heart disease, and stroke over the course of what we hope will be a very long lifetime for you.

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Response by:

Mildred   Lam, MD Mildred Lam, MD
Associate Professor of Medicine
School of Medicine
Case Western Reserve University