What is the next step in evaluating a 38-year-old man with microscopic hematuria, showing moderate blood on dipstick urinalysis and 10-15 red blood cells (RBC) per high power field (hpf) with over 80% dysmorphic cells?

From the Guidelines

The next step for this 38-year-old man with microscopic hematuria is nephrology referral (option C). The presence of dysmorphic red blood cells (>80%) strongly suggests a glomerular source of bleeding rather than a urologic cause, as noted in the study by 1. Dysmorphic RBCs occur when red blood cells pass through damaged glomeruli and become distorted. This finding, combined with the absence of gross hematuria, points toward a kidney disease process such as glomerulonephritis rather than a structural abnormality in the urinary tract.

Key Considerations

• A nephrologist is the appropriate specialist to evaluate glomerular pathology, perform additional testing such as protein quantification, serologic studies for autoimmune conditions, and potentially a kidney biopsy if indicated.
• While urologic evaluation with CT urogram or cystoscopy would be appropriate for patients with non-glomerular hematuria (where RBCs appear normal/isomorphic), these tests would likely be low-yield given the clear evidence of glomerular bleeding in this case, as suggested by 1.
• Prompt nephrology evaluation is important as early diagnosis and treatment of glomerular diseases can prevent progression to chronic kidney disease.

Rationale for Choice

• The study by 1 provides guidance on the initial evaluation of asymptomatic microscopic hematuria, emphasizing the importance of identifying glomerular disease.
• The more recent study by 1 offers high-value care advice from the American College of Physicians, including the consideration of urology referral for cystoscopy and imaging in adults with microscopically confirmed hematuria, but this is more relevant to cases without clear evidence of glomerular bleeding.
• Given the presence of >80% dysmorphic RBCs, the focus should be on evaluating and managing potential glomerular pathology, making nephrology referral the most appropriate next step.

From the Research

Evaluation of Microscopic Hematuria

The patient presents with microscopic hematuria, defined as 10-15 RBC/hph with >80% of the cells appearing dysmorphic. The next step in evaluation should consider the following:

• The presence of dysmorphic red blood cells (dRBCs) is indicative of glomerular disease, but does not preclude urological disease 2
• A study found that among patients with ≥40% dRBCs, 34.0% had urological disease and 28.9% had glomerular disease, highlighting the importance of not omitting urological evaluation 2
• The American Urological Association guideline recommends further urological evaluation, even in the presence of dRBCs 2

Diagnostic Approach

Consider the following diagnostic approaches:

• Urine cytology may be useful in evaluating for urological malignancies, but is not the next step in this case
• Repeat microscopic urinalysis may be necessary to confirm the presence of hematuria and dRBCs
• Nephrology referral may be considered if glomerular disease is suspected, but urological evaluation should not be omitted 2
• CT urogram may be useful in evaluating for urological disease, but is not the next step in this case
• Cystourethroscopy may be necessary to evaluate for urological disease, particularly if urological malignancy is suspected

Recommendations

Based on the evidence, the next step in evaluation should be:

• Repeat microscopic urinalysis to confirm the presence of hematuria and dRBCs, followed by further evaluation for urological and glomerular disease as indicated 2, 3, 4, 5