Microhematuria in Potential Kidney Donors

The key aspect of the workup for a potential kidney transplant donor is ensuring that donation does not result in future health problems for the donor. For the most part, this boils down to determining whether or not the potential donor is at risk for future kidney injury. For some conditions this is an easy decision to make (e.g., in a family with ADPKD where the potential donor's PKD1/PKD2 genotype status is known), but for other conditions the decision becomes a tougher one.

One such example is asymptomatic microhematuria in the potential kidney transplant donor. How does one work this up and what are the recommendations? Potential causes of persistent microscopic hematuria include subclinical IgA Nephropathy, Alport's Syndrome, thin basement membrane disease, PKD, urologic malignancy, subclinical nephrolithiasis and/or hypercalciuria/hyperuricosuria, AV malformations & fistulas, and (in endemic areas such as the Middle East) bladder schistosomiasis. A 2007 Kidney International paper by Vadivel et al reviews the subject, and suggests that all potential donors with microscopic hematuria should undergo a detailed family history (to rule out IgA Nephropathy & Alport's, which are contraindications to donation; thin basement membrane disease is considered okay provided there is no family history of renal compromise), urine culture (to rule out chronic infection), 24-hour urine studies (to rule out stone disease), urine cystoscopy & cytology (to rule out malignancy), and a CT scan with iv contrast (to look for stone disease and malignancy). Furthermore, the authors suggest that if the above workup is inconclusive for cause, a renal biopsy should be performed. Obviously, a detailed discussion regarding the risks/benefits of donation with the potential donor is warranted with every patient, but is particularly relevant with this subgroup.