Microscopic Hematuria
Approach
Microscopic hematuria definition: Appropriately collected void with
3 or more RBCs per high-powered field
No evidence of infection
Evaluation
“Dirty sample,” e.g. > 3 bacteria species and/or multiple squamous cells: Repeat U/A
Urinalysis suggestive of UTI, e.g. positive leukocyte esterase +/- nitrites: Treat UTI
Patient menstruating or other reasonable explanation (e.g. calcium oxalate crystals on U/A, recent history of vigorous exercise/trauma): Repeat U/A in 6 weeks
Age > 35 years: Refer to urology for cystoscopy if any of the following apply
No alternative explanation, e.g. exercise, trauma, illness, infection
Patient has any risk factors for urinary malignancy, e.g. excessive NSAID use, smoking, exposure to chemical dyes
Consider referral to nephrology for any the following findings on urinalysis:
Proteinuria in the setting of DM, HTN, and/or elevated creatinine levels
Presents of albumin and/or cellular casts
AAFP Algorithm for Asymptomatic Microhematuria (2013)
Differential
Step 1: Rule out urinary tract infection as per definition (see above)
Step 2: Consider
Other renal disease
Step 3: If no obvious diagnosis, rule out renal malignancy and/or prostate cancer
Pyuria
Nitrite positive: Suspect Gram negative Enterobacterales species, e.g. E. coli, Klebsiella, P. mirabilis
Nitrite negative: Suspect Gram positive species, e.g. Enterococcus faecalis, Staphylococcus saprophyticus
Sterile pyuria etiology
Contamination: Obtain morning (preferably first void) clean catch, mid-stream sample
With hematuria
Contamination, e.g. menstruation
Chronic interstitial nephritis