Major etiologies of hematuria and details of available tests were discussed in Chapter 12. The problem of hematuria is somewhat different from that of proteinuria. About 4% (range, 1.2%-9%) of asymptomatic men under age 40 have microhematuria of two or more RBCs per high-power field compared with about 15% (range, 13%-19%) of clinically healthy men over age 40 years. A major consideration is not to overlook genitourinary system cancer. Hematuria is the most frequent symptom of bladder and renal carcinoma, being reported in about 80% (range, 65%-85%) of bladder carcinoma and about 60%-70% (range, 32%-80%) of renal carcinoma. Gross hematuria comprises the majority of hematuria in both bladder and renal carcinoma. About 98% of bladder carcinoma and about 96% of renal carcinoma (not including Wilms’ tumor of childhood) occurs after age 40. Renal carcinoma is reported in about 1% (range, 0%-2.0%) of patients with hematuria of any type under age 40 years and in about 1.5%-2.0% (range, 0.4%-3.5%) in patients over age 40 years. Bladder carcinoma is reported in about 3% (range, 0.2%-8.0%) of patients with hematuria under age 40 years and in about 7%-10% (range, 0.1%-15%) of patients over age 40 years. In younger patients, several investigators have found IgA glomerulonephritis in 35%-40% of patients with gross or considerable microscopic hematuria in whom renal biopsy was performed. Over age 40, gross hematuria is much more strongly associated with cancer (although less frequently, neoplasia may present with microscopic hematuria and sometimes may be discovered with a completely normal urinalysis). Therefore, in persons under age 40 years (and especially between age 10 and 30 years) with gross hematuria, the majority of investigators do not expect cancer and do not favor extensive workup unless hematuria persists or there are other symptoms that suggest cancer. However, this opinion is not unanimous. In persons over age 40 with gross hematuria, the standard response would be, as a minimum, an IVP and cystoscopy (if the IVP results were negative).

In persons under age 40 years with microscopic hematuria, most investigators question the need for additional investigation unless other symptoms suggest cancer or hematuria persists. In patients over age 40 years with asymptomatic microscopic hematuria only, especially if there are relatively few RBCs, opinion is divided whether to test further, and how much. Presence of other symptoms greatly increases pressure for further tests. Substantial numbers of RBCs (>10 RBCs per high-power field) also seem to influence opinions, although most studies have shown rather poor correlation in microhematuria between presence of cancer and the number of RBCs in the urine sediment. Also, it must not be forgotten that the patient may have hematuria due to carcinoma of the kidney or bladder and at the same time have other diseases, such as hypertension, which themselves are known causes of hematuria. Finding RBC casts means that the RBCs are from the kidney and that the problem is a medical disease rather than cancer.
RBCs or hemoglobin (from lysed RBCs) in the urine may appear because of contamination during specimen collection. Female vaginal secretions may contain RBCs, WBCs, or both. A significant number of squamous epithelial cells in urine sediment (arbitrarily defined as more than 10 squamous cells per low-power field) suggests possible contamination, and the study should be repeated using a midstream voided specimen. It may be necessary to assist the patient with expert personnel.