Urine beta-thromboglobulin concentration or beta-thromboglobulin/creatinine ratio in single voided urine samples...

Different procedures are currently used in the urine beta-thromboglobulin (BTG) assay. We investigated the reliability of limited urine collections and of different expressions of urine BTG results (concentration, urine BTG/creatinine ratio) for the measurement of hourly or daily BTG excretion rates. BTG was measured by a sensitive RIA method in various urine collections of normal subjects (n.80) and patients (n.120) with miscellaneous diseases where an enhanced in-vivo platelet activation could be expected. The BTG concentration in a 6-hour urine collection appeared to change in relation to the urine flow rate (r = -0.53 in normals, r = 0.27 in patients, p less than 0.01) and urine osmolality (r = 0.46 in normals, r = 0.31 in patients, p less than 0.01). In both normals and patients not a very good correlation was observed between the urine BTG/creatinine ratio and the BTG excretion rate (r = 0.54 and r = 0.48; p less than 0.001, respectively). Variable coefficients of correlation (r = 0.83-0.34) were observed between the BTG excretion rate of single voidings of the morning, afternoon-evening and night and the daily BTG excretion both in normals and patients. Reliable measurements of the BTG in urine should be expressed as the hourly excretion rate in a given period of the day for limited urine collections or as the daily excretion for 24-hour urine collections.