CKD values in blood work

I had blood work before a heart ablation and a watchman implant. The CKD reading was 72.4 on aug 27 and 89.5 on sept. 15. I was ask several times by a nurse had I ever been told I had CKD. And I have not. I was just wondering if the reading were off because of fasting and dehydration or should I be concerned and push the issure with my GP