What does it mean when red blood cells are elevated in a routine urinalysis?

“Urinalysis red blood cells” refers to erythrocytes detected during routine urinalysis—the third of three cell types examined. Normally, urine contains no red blood cells (RBCs) or only an occasional RBC. However, if microscopic examination of centrifuged urine reveals an average of 1–2 RBCs per high-power field (HPF), this is considered abnormal. When urine appears pink, red, or resembles “meat-wash water,” it indicates gross hematuria. Common underlying conditions include acute glomerulonephritis, chronic glomerulonephritis, renal tuberculosis, and renal tumors. So, what causes elevated red blood cells in routine urinalysis? Below we address this question.

What Causes Elevated Red Blood Cells in Routine Urinalysis?

1. Hematuria

Hematuria may result from various medical conditions, including glomerulonephritis, Henoch-Schönlein purpura nephritis, urinary tract infections (UTIs), and coagulation disorders. Surgical causes include urolithiasis (stones) and neoplasms; definitive diagnosis requires correlation with associated symptoms. For instance, edema and hypertension suggest glomerulonephritis. Additionally, urinary tract tumors—by eroding adjacent mucosa or undergoing necrosis—may cause elevated RBCs and even gross hematuria.

2. Urinary Tract Infection (UTI)

During UTIs, the urothelium becomes congested and edematous, often accompanied by bleeding. Acute hemorrhagic cystitis, in particular, commonly presents with visible gross hematuria. In such cases, infection is the primary etiology, necessitating antimicrobial therapy. Regardless of the underlying cause, any imbalance between RBC production and destruction leads to quantitative or qualitative abnormalities, thereby contributing to disease pathogenesis.

3. Urolithiasis

Urinary stones can abrade local mucosa, resulting in bleeding and elevated RBCs on urinalysis. Patients typically experience pain localized to the stone’s site—such as flank or abdominal pain—requiring renal and bladder ultrasonography for confirmation. If urine protein is negative, isolated RBC elevation generally poses no threat to kidney function and warrants only repeat testing. However, if proteinuria is concurrently positive, prolonged proteinuria may impair renal function and necessitate pharmacotherapy.

The above outlines potential causes of elevated red blood cells in routine urinalysis. We hope this information is helpful to you!