β2‐microglobulin measurement with dried urine spots for congenital anomalies of the kidney and urinary tract screening in 3‐year‐old children

Abstract

Background Screening using dipstick urinalysis has long been performed in 3‐year‐old children; however, it is ineffective in detecting congenital anomalies of the kidney and urinary tract (CAKUT). Measurement of the urinary β2‐microglobulin (β2MG)/creatinine (Cr) ratio may be more effective for this purpose. Analysis of dried urine spots (DUS) on filter paper is suitable for mass screening since operational costs are low and samples are easy to collect and transport. We examined the accuracy of measuring the urinary β2MG/Cr ratio in DUS on filter paper. Methods We collected 2,623 urine samples from 3‐year‐old children. β2MG and Cr levels were measured in DUS on filter paper. We examined the correlation between the β2MG/Cr ratios measured in DUS and using the conventional method in 640 samples using the coefficient of determination test. Children with high β2MG/Cr ratios (>0.6 µg/mg Cr) in DUS samples were further examined to establish a definitive diagnosis. Results There was strong correlation between the two methods for determination of β2MG levels (r2 = 0.68; P < 0.001) and β2MG/Cr ratios (r2 = 0.69; P < 0.001). Of the 2,623 children, 38 (1.45%) had β2MG/Cr ratios >0.6. Thirty‐five children were subsequently examined, resulting in findings of renal hypodysplasia (n = 2, 0.08%), horseshoe kidney (n = 1, 0.04%), renal tubular dysfunction with hepatoblastoma (n = 1, 0.04%), data abnormality (high urine β2MG level, n = 6, 0.23%; high serum Cr level, n = 1, 0.04%), and normal values (n = 24, 0.91%). Conclusions We evaluated a practical method for measuring β2MG/Cr ratios in DUS as a screening method to detect CAKUT in 3‐year‐old children.

A Systematic Literature Review on the Use of Dried Biofluid Microsampling in Patients With Kidney Disease

“…Interestingly, one study compared DBS and hair samples and indicated that 87% of hair samples and 84% of DBS samples demonstrated treatment adherence [ 25 ]. In the case of dried urine spots, one study compared it to matched urine samples with a moderate correlation ( R = 0.68 and 0.69, p < 0.001) for β2‐microglobulin and β2 microglobulin/creatinine concentration ratios, respectively [ 26 ].…”

“…Using 2813 paediatric patients from two studies, 2623 DUB and 190 DBS samples were used to screen for congenital anomalies of the kidney and the urinary tract [ 17 , 26 ]. The samples were used to identify creatinine levels and urine β2‐microglobulin (β2‐M), demonstrating that either DUS or DBS were deemed suitable for mass paediatric screening [ 17 , 26 ].…”

“…Using 2813 paediatric patients from two studies, 2623 DUB and 190 DBS samples were used to screen for congenital anomalies of the kidney and the urinary tract [ 17 , 26 ]. The samples were used to identify creatinine levels and urine β2‐microglobulin (β2‐M), demonstrating that either DUS or DBS were deemed suitable for mass paediatric screening [ 17 , 26 ]. One utilised tandem mass spectrometry [ 17 ] to measure creatinine while the other measured samples either via an enzyme‐linked immunosorbent assay or latex photometric immunoassay for creatinine and β2‐M, respectively [ 26 ].…”

“…The reduced cost of dried biofluid microsampling is a frequently cited advantage of microsampling. A total of 10 studies (14.9%) stated that dried biofluid microsampling was cheaper relative to traditional venous blood collection [ 24 , 26 , 29 , 32 , 38 , 43 , 56 , 66 , 72 ]. This was due to reduced costs associated with sample preparation, consumables and storage at room temperature [ 24 , 32 , 56 , 72 ].…”

“…[ 45 ] performed a cost analysis of DBS compared with conventional sampling, resulting in a 61% societal and 21% healthcare cost saving for patients with kidney disease. Dried urine spots were estimated to cost $6.4/person including consumables, labour and delivery costs [ 26 ].…”