3 3 8 Editorial correspondence The Journal of Pediatrics August 1991

R E F E R E N C E S

1. Pichichero ME, Disney FA, Talpey WB, et al. Adverse and beneficial effects of immediate treatment of group A beta-he- molytic streptococcal pharyngitis with penicillin. Pediatr In- fect Dis J 1987;6:635-43.

2. Gerber MA, Randolph MF, DeMeo KK, Kaplan EL. Lack of impact of early antibiotic therapy for streptococcal pharyngi- tis on recurrence rates. J PEDIATR 1990;117:853-8.

3. Stollerman GH. Rheumatic fever and streptococcal infection. New York: Grune & Stratton, 1975:21-45.

4. Brock LL, Siegel AC. Studies on the prevention of rheumatic fever: the effect of time of initiation of treatment of strepto- coccal infections on the immune response of the host, J Clin Invest 1953;32:630-2.

5. Potter EV, Stollerman GH, Siegel AC. Recall of type-specific antibodies in man by injections of streptococcal cell walls. J Clin Invest 1962;41:301-10.

6. Siegel AC, Johnson EE, Stollerman GH. Controlled studies of streptococcal pharyngitis in a pediatric population. N Engl J Med 1961 ;265:566-7l.

7. Randolph MF, Gerber MA, DeMeo KK, et ai. Effect of anti- biotic therapy on the clinical course of streptococcal pharyn- gitis. J PEDIATR 1985;106:870-5.

8. Gerber MA, Randolph MF, Chanatry J, et al. Five vs ten days of penicillin V therapy for streptococcal pharyngitis. Am J Dis Child 1987;141:224-7.

9. Gerber MA. Comparison of throat cultures and rapid strop tests for diagnosis of streptococcal pharyngitis. Pediatr Infect Dis J 1989;8:820-4.

10. Gordis L, Lilienfeld A, Rodriguez R. Studies in the epidemi- ology and preventability of rheumatic fever. III. Evaluation of the Maryland rheumatic fever registry. Public Health Rep 1969;84:333-8.

Mean corpuscular volume as an aid in identifying the cause of hematuria

To the Editor." Tsukahara e ta l . 1 reported the usefulness of determining the

mean corpuscular volume (MCV) in urinary erythrocytes as an aid in determining the source of hematuria; histograms revealed pop- ulations of urinary erythrocytes that had an MCV less than 50 #m 3. The authors concluded that urinary erythrocytes with an MCV less than 50 #m 3 originate from the glomerulus, whereas MCVs >50 #m 3 were of nonglomerular origin.

We recently examined 31 children, aged 3-18 years, with hema- turia of known etiology. Sixteen of these children had glomerulo- nephritis and 15 had nen-glomerular types of hematuria. Erythro- cytes were examined by light microscopy and analyzed by a Coulter counter by a laboratory technician unaware of the etiology of he- maturia.

In all 31 children the MCV of the total erythrocyte pool was greater than 50 ~zm 3. Examination of individual histograms re- vealed subpopulations of erythrocytes with a peak less than 50 ~m 3 in 20 children. Fifteen of these patients had glomerulonephritis; five had nonglomerular sources of hematuria. All patients with glom- erulonephritis had peaks less than 50 um 2. Thus there were no false-negative tests among children with gtomerulonephritis, but 5

of 15 children without glomerulonephritis also showed similar peaks. Nonglomerular disorders with a population of erythrocytes with an MCV less than 50 #m 3 included a child with hypercalci- uria, another with urinary tract infection, and one with pyelone- phritis; two children had ureteral reimplantations. Determination of erythrocyte morphology by light microscopy demonstrated a similar lack of specificity in determining the origin of hematuria.

Although determination of MCV of urinary erythrocytes may be supportive in the diagnosis of glomerulonephritis, determination of individual histograms is required. We suggest further studies of the usefulness of this diagnostic test before general clinical application.

David lkola, MD Pediatric Resident

F. Bruder Stapleton, MD Professor and Chairman

Department of Pediatrics State University of New York at Buffalo

and Children's Hospital ~?f Buffalo Buffalo, N Y 14222

R E F E R E N C E

1. Tsukahara H, Yoshimoto M, Morikawa K, Okada T, Kuroda M, Sudo M. Urinary erythrocyte volume analysis: a simple method for localizing the site of hematuria in pediatric patients. J PEDIATR 1989;115:433-6.

Reply

To the Editor: In our study I the urinary erythrocyte volume distribution curves

(UEVDCs), measured with automated blood cell analyzers, were categorized according to the distribution pattern and not the mean cellular volume (MCV) of urinary erythrocytes. The pattern is de- fined as "glomerular" or "nonglomerular" when the UEVDC peaks only at a volume <50 p.m 3 or >50 #m 3, respectively. The pattern is defined as "mixed" if peaks are observed at both <50 #m 3 and >50 #m3; a "glomeruIar" type of distribution pattern is interpreted as indicating glomerular hematuria, and both "'nonglomerular" and ',mixed" types indicate nonglomerular hematuria. As sug- gested by DeCaestecker et al. 2 and Gibbs et al., 3 the subpopulation of particles with a peak at a volume <50 #m 3 in the "mixed" type is likely to result from the coexistence of debris (i.e., fragmented cells, crystals, microorganisms, and miscellaneous urinary contam- inants). In contrast to our results and those of Docci etal., 4 Shich- iri et al. 5 found that 15 (47%) of 32 patients with urinary tract in- fection (UTI) and nonglomerular hematuria had the "glomerular" type of distribution pattern. Although Shichiri et al. did not con- sider the reasons for this, we speculate that those l 5 patients voided urine that was contaminated by much debris derived from UTI. However, UT1 is usually easy to diagnose clinically. As a summary of the previous data, L 4-6 the analysis of UEVDCs has high spec- ificity (128/131 = 98%) and sensitivity (174/176 = 99%) in iden- tifying the glomerular source of hematuria, if patients with UTI are excluded. Conventional morphologic examinations of urinary eryth- rocytes can never attain such high specificity. 5,6

Of the 80 patients with hematuria in our study, we determined