Just in case others may experience what I just did I will give my most recent experience: (when we compare our test result numbers on here remember they may all be wildly different numbers but mean the same thing)":
Due to my stage 3 egfr (caused by only one kidney) and renal metastatic cancer, I get all sorts of testing. some every 3 weeks (blood), some as required (scans, etc.) and some every 3 months (urine).
I generally go to one of our local hospitals for my tests. Lets call it Hospital "A". They post the results online so I can see them immediately, long before my doctors appointments. Recently another hospital nearer to me, call it Hospital "B" also started to post tests online for immediate review. So I went to them for a urine test.
Everything came out normal or negative (good result). I pay particularly close attention to my Urine Mirco-albumin level (protein). It was "less than 6 mg/dl" classified as normal. But in my mind this seemed higher than what I'm used to reading. So I looked at my last few tests at hospital "a" (that I've normally used). There all my tests report "less than .5 mg/dl". Naturally worry overcame me. What?? My level jumped from <.5 up to 6! not .6, but 6!! Both reported as mg/dl.
Then after repeated inspection of the results I noticed something. The normal range for the hospital report 6mg/dl, was set at less than 30mg/dl. So to them anything less than 30mg/dl is normal. And they measured 6. BUT the old hospital considers the normal range anything less than 3mg/dl as normal so my .5 value is normal.
So while they both reported my result as mg/dl their scale of normal for one lab was less 3.0 mg/dl and the other was less than 30 mg/dl.
SO, when we on here report to each other our test results we must consider the lab that produces the results have DIFFERENT normal ranges. Look at my example. If I wrote to you my result was .5 and another time it was 6.0, it would look like some dramatic change. But actually based upon the "normal" range for each lab, they are basically the same!!!