Asymptomatic microhematuria: an indication of hereditary hemorrhagic telangiectasia?

Hereditary hemorrhagic telangiectasia (HHT) is a genetic angiodysplasia affecting multiple organs. Clinical manifestations include spontaneous and recurrent epistaxis, mucocutaneous telangiectases that bleed easily and arteriovenous malformations in many organs. Despite the anecdotal recommendations of some groups, to our knowledge information regarding the prevalence of microscopic hematuria (MH) in patients with HHT has not been reported to date. We evaluated the prevalence of MH in patients with HHT.

Between January 2002 and June 2003, 116 consecutive patients with HHT were studied, of whom 20 were excluded because of a possible false-positive MH bias. Therefore, 53 males and 43 females with a mean age +/- SD of 45.8 +/- 15.8 years who had HHT underwent urine dipstick testing for heme and microscopic urinary examination. A control group of 192 males and 148 females with a mean age of 46.5 +/- 14.2 years and no statistical age or sex differences without HHT who were hospitalized in the same period at the same medical unit for gastrointestinal disorders was compared to the HHT cohort.

MH was detected in 45 of 96 patients with HHT (47%) compared to 41 of 340 controls (12%) (p <0.0005). None of the patients with HHT showed abnormal renal function, proteinuria, hypercalciuria or hyperuricosuria. MH was due to glomerular hematuria in 29 of 45 patients (65%), postglomerular hematuria in 13 (29%) and mixed hematuria in 3 (6%). No gross hematuria was detected.

Our results show that MH is common in patients with HHT. This might indicate the possibility of weak urinary tract bleeding due to telangiectases and/or small arteriovenous fistulas, which are typical HHT lesions. Therefore, HHT should be considered among the causes of MH. Urinalysis should always be performed when there is severe anemia in HHT patients with HHT, particularly those without other apparent bleeding sites.