@biowicks CKD stands for chronic kidney disease. I’m not aware of a test called CKD (or CDK). The tests for kidney function as @maggieinfp said is a Renal Panel. She described it really well. The most common part of that is the eGFR. It stands for estimated glomeruler (sp?) filtration rate which reflects the overall kidney function. Another valuable test is a Cystatin C test but is less common than the eGFR.