Hi I Had An Second Blood Test Did The Kidneys

Hi I had an second blood test did the kidneys first one its that its was low and advice to have another one in month the second one is borderline I am seeing doctor on Monday first test was 59 and know they sYing it borderline my cholesterol is 5.5 and I am low iron can you help me understand as they want me to have another bloods test for my kidneys in 3months