All issues > Volume 30(9); 1987

Original Article

J Korean Pediatr Soc. 1987;30(9):1014-1020. Published online September 30, 1987.

Clinical Value of Urinary β₂ -Microglobulin in Patients with Urianry Tract Infection.

Nak Uk Sung¹, Chang Ryul Kim¹, Jeh Hoon Shin¹, Woo Gill Lee¹

¹Department of Pediatrics, College of Medicine, Han Yang University, Scotti, Korea

Abstract

Urinary tract infection (UTI) in children is relatively common infectious disease and it may be the forerunner of severe renal diseases in adulthood. The site of infection is an important factor in the evaluation of the clinical course, treatment and prognosis of patients with UTI, because patients with bacteriuria of renal origin (pyelonephritis) are probably at risk of developing the renal parenchymal reduction seen in some of these patients. Several methods have been developed to determine the site of UTI, but there was no best reliable single test at present. β₂ -microglobulin ( β₂ -MG) is a low molecular weight protein, which exists in the serum, urine, cerebrospinal fluid, saliva, colostrum and amniotic fluid, etc. It passes the glomerular membrane easily and is normally reabsorbed in proximal renal tubule, where it is catabolized. So urinary β₂ -MG is increased in patients with clinically pyelonephritis indicated severe tubular damage. 24 hour urinary β₂ -MG was measured in 25 patients with UTI and 24 patients (not jnclude known renal diseases, chronic infectious diseases, autoimmune diseases and malignancies) as control. The results obtained were as follows: 1) Mean value of 24 hour uriary β₂ -MG in upper UTI was 806.1 ±325.0 ㎍ , that of lower UTI was 72.2±27.5 ㎍ , and control was 82.5±12.1㎍ There were statistically significant difference between upper and lower UTI or control (p<0.05), but no significant difference between lower UTI and control (p>0.05). 2) 24 hour urianry β₂ -MG value higher than 100㎍ had sensitivity of 71% for indicating upper UTI and lower than 100 ㎍ had specificity of 73% indicating lower UTI. 3) On urinary LDH isoenzyme electrophoresis, upper UTI showed as follows; type 1, 28.2±5.3%: type 2, 25.4±3.8%: type 3, 17.9±1.6%: type 4, 13.8±3.2%: type 5, 15.0±5.7%, and lower UTI showed as follows; type 1, 43.9±2.9%: type 2, 28.6±4.7%: type 3, 11.9±0.7%: type 4, 7.9±2.3%: type 5, 7.8± 1.0%. They revealed that upper UTI had higher value than lower UTI in type 4 and type 5, and lower UTI had higher value than upper UTI in type 1 (p<0.05). 4) Positive rate for CRP was 58% in the upper UTI whereas 20% in the lower UTI, which showed statistically significant difference between two groups (p<0.05). 5) There were no significant difference between upper and lower UTI in 24 hour urinary total LDH, ESR and WBC counts (p>0.05). It is suggested that the measurement of 24 hour urinary β₂ -MG is relatively simple reliable non-invasive method to determine the site of UTI, and if accomplished with urinary LDH isoenzyme electrophoresis and CRP, it may be more helpful in differentiation of upper and lower UTI.

Keywords :microglobulin; C-reactive protein; Erythrocyte sedimentation rate; Lactic dehydrogenase and its isoenzyme; Upper and lower urinary tract infection; White blood cell counts.