My 7-year-old daughter had bloodwork done to try to understand why she has constant stomachaches. A CBC was done and her BUN level came back slightly elevated at 19 (ref. range 5-18 mg/dL) but her BUN/creatinine level is significantly elevated (in my opinion) at 63 (ref. range 13-32). All other parameters tested are within normal ranges. Should I be concerned and what further steps would you recommend?

The Blood Urea Nitrogen (BUN) test could be elevated because of dehydration in someone who has a stomach ache.  I do not have much confidence in the BUN to creatinine ratio.  I do not find it a helpful test.  I suggest that you discuss your concerns with your daughter’s pediatrician.