I'm not sure what to make of my blood tests. Do I have chronic kidney disease, or just exhibiting signs of aging? According to eGFR, they are getting worse. And why the one year improvement in 2004? I'm trying to dig into this with my pcp a bit more and I went for a follow up blood test and spot urine test this morning. For 48 hours leading up to the test, I did not excercise, eat meat or drink caffeine, but I did drink a lot of water hoping for a best case scenerio. Here are my past results (where I did not pay any particular attention to how I prepared) and some hopefully relevant background information.

BUN = 15 ('07), 23 ('06), 20 ('04) 21 ('01).
Creatinine = 1.4 ('07), 1.4 ('06), 1.1 ('04) 1.3 ('01).
BUN/Creatinine = 10.7 ('07), 16.42 ('06), 18.2 ('04) 16.2 ('01).
eGFR = 58% ('07), 59% ('06), 78% ('04) 65% ('01).
All other metabolic indicators (calcium, sodium, potassium, CO2, chloride) have been consistantly normal.

I have never had a urine test to correlate with the blood work-up because kidney function was always considered within the normal range, however when I do the eGFR calculation I'm down to 58% (stage 3), which scares me a bit. The big drop in eGFR seems primarily based on age. Am I wrong?

Background: I'm 45 year old male and my metabolism has gone through another change over the last 5 years whereby I have gained approximately 10 pounds, now at 166lbs at height of 6'1". Although I don't have a regular excercise routine, I am physically very active. I have had quite a bit of solvent exposure over the years and I was taking quite a lot of pain meds in 2004-5 for knee pain, but have since had surgery to correct problem. No diabetes. I used to donate blood every 8 weeks, but quit in Jan '07 after becoming anemic and iron poor after switching to the apheresis method (I'm fine now). I'm wondering if this is related to my kidney function? I drink 1/4 to 1/2 gallon of fluids/day, typically closer to 1/4 gal and typically milk and/or tea. Urine typically fairly dark and strong unless I up the fluids, but I forget to drink more. My blood pressure is typically measured at 120/70, but I am type-A personality. Since 1994, my cholesterol consistantly hovers around the limit (200 total, 130 LDL, 55 triglycerides), although in 2004 the total was down to 174 - also the year eGFR was better (a connection??).

Any thoughts would be very much appreciated.:)

Thanks for the support, Allie. Think insurance company's don't create potential delays in diagnosis? They do. (I'm sure you already knew this.) My doctor recommended I do the follow up test after drinking lots of water to rule out dehydration as a cause, but as a blood test only, hoping not to trigger the insurance company's awareness of a potential kidney problem before it is confirmed - or else I'm labeled for life. I appreciated the effort, but in light of the low eGFR, I said I didn't want to waste time and suggested it might be a good idea to see if the urine test corroborates the blood test this go around. He agreed, but he explained that with the two tests outside of a regular check-up, it is harder to come up with a code on the lab request that does not flag the kidneys and they'll insist on a diagnosis from him because of it. We will talk after the latest test results come back. He did say, if the test confirms past results, I should probably see a nephrologist at that point.

Interestingly, my blood test taken this past January ('07) was the first to come back with an eGFR number. Prior to that, my creatinine numbers, while a bit high, didn't seem too alarming as they were within the "normal" range for men. For this reason, I think my pcp overlooked their significance, as did I. I have to question how a creatinine level that means I have lost almost half my kidney function can be considered normal.

At any rate, I'm just now trying to look back at my blood work history and look for patterns and possibly when things went bad and why. Looking at 2004, either the lab was off or there is a possible link between cholesterol level and creatinine level, so I will try to work hard on bringing this down. I'm also going to work on staying better hydrated and eat less meat so as to make life a little easier for my kidneys.

I got ahold of a world renowned doctor friend of mine and he tells me while my creatinine is a bit high for my age, the eGFR is not very accurate and I should wait for results to determine an actual GFR before thinking there is a real problem. He also said the cholesterol connection is "hogwash" and an undiagnosed hypertension problem is not a likely cause. He would have preferred I submitted to a 24 hr urine test rather than the random (spot) urine microalbumin test I did submit to because, he says, it is considered the only way to measure GFR directly in his circles. I'll wait for the test results and report back. For now, I'm off on vacation where I'll try not to worry about this.

Got my latest blood and spot urine results back. Remember, this time around I donated "first-urine-of-the-day", and I drank lots of water (0.5 gal/day versus .25 gal/day milk and tea), didn't exercise or drink caffeine and ate no red meat the week leading up to testing for a "best case scenerio" on the test. The blood results were unchanged from January. Creatinine still at 1.4
mg/dL, all other metabolic rates normal and similar. The microalbumin
(spot) urine test came back with a urine creatinine level of 85.6 mg/dL,
microalbumin levels below 5 mg/L and microalbumin/creatinine "unable to
calculate - below measurable levels". All other urinalysis indicators
normal. This last round of tests rules out dehydration during earlier
tests.

In the meantime, I was able to collect some earlier blood tests from
previous pcp's. It seems I had a creatinine level of 1.2 dating back to
1996, so the level hasn't changed all that much in 11 years. Based on that
and the fact that no albumin was detected, it would seem positive that
whatever is going on is at a very early stage or somewhat stable,
glomerular membrane permeability is unaltered and, counter to what was suspected earlier by my pcp, that hidden hypertension may not be involved.

I haven't spoken with him directly, but received a letter from my pcp while
away recommending next that I see a nephrologist and do an ultrasound of my kidneys, prostate and bladder to check for blockage, etc. I admit, I no
longer create enough urine pressure to write my name in the snow and, for a
period, had a hard time shutting it off. I would guess, a 24hr urine
sample to get an accurate creatinine clearance rate would also be in order.

Question: Does the urine creatinine level above seem to correlate with the serum creatinine level indicating slightly lowered kidney function or is it normal? Do I need the 24 hr results to be sure? I think my pcp still suspects a hidden hypertension problem as a possible cause of elevated serum creatinine, but wants to rule out other things first.

I next see the nephrologist on Aug 9.