<s>[INST] Hi. Life insurance tests found blood in my urine: WBC 12 RBC 28 and high Creatinine 96 (UK system) Phosphate in urine was 1.48 They estimate my GFR as 58 I am 41, non smoker, otherwise healthy. Does this mean I have kidney disease or could it just be an infection? Could the test be wrong if I ate a beef with coca cola dinner 9 hours before? Also they used first morning urine and my period came 5 days later. I don t know if these things are irrelevant. :o/ [/INST] Thank you for using Chat Doctor The presence of microscopic hematuria which is what you are describing may or may not indicate kidney disease. A kidney stone or any mechanical blockage within the urinary tract can cause microscopic hematuria. Since you are menstruating, this may be confounded vaginal blood admixing with the urine specimen.  To exclude kidney disease you would need: Blood chemistries to assess creatinine and BUN, kidney ultrasound, clean-catch urinalysis and quantification of urinary protein excretion. Once your physician has the above data, they should be able to answer definitively if you have kidney disease or not. What you had done is take an insurance physical which basically cast a large net "fishing for abnormalities" such that if there are any, they can deny you insurance or raise your premium.  It is not a diagnostic test rather a screening tool. Consumption of animal protein prior to the studies may have increased the urinary creatinine excretion but should not affect hematuria Take care and be well </s>