Consistency between morning and 24-hour urinary biochemisty

Objective To explore the consistency between morning and 24-hour urinary biochemistry/creatinine. Methods Totally 60 patients with urinary system lithiasis hospitalized in a Class Ⅲ hospital from February 2017 to April 2018. The calcium, sodium, potassium, magnesium, phosphorus, chlorine, uric acid, urea nitrogen and creatinine in their morning and 24-hour urine was tested. Meanwhile, a total of 29 healthy student volunteers were selected as a control group. Results After calibration and log transformation of morning and 24-hour urinary biochemistry/creatinine, the correlation coefficient r in the healthy group was 0.58-0.77 (P<0.05) , while the r value in the lithiasis group was 0.07-1.04 except the log of urea nitrogen and creatinine (P<0.05) . According to the Bland-Altman consistency analysis, the consistency of the log of uric calcium/creatinine in the healthy group ranged from -0.35 and 0.19, while that in the lithiasis group was -0.53-0.82; the log of uric potassium/creatinine in the healthy group was -0.35-0.57, while that in the lithiasis group was -0.53-0.66; the log of uric chlorine/creatinine in the healthy group was -0.33-0.86, while that in the lithiasis group was -0.90-1.04; the log of uric sodium/creatinine in the healthy group was -0.38-0.96, while that in the lithiasis group was -0.73-0.97; the log of urea nitrogen/creatinine in the healthy group was -0.17-0.39, while that in the lithiasis group was -0.70-0.81; the log of uric acid/creatinine in the healthy group was -0.15-0.48, while that in the lithiasis group was -0.29-0.37; and the log of urea magnesium/creatinine in the healthy group was -0.28-0.60, while that in the lithiasis group was -0.36-0.57. Conclusions The consistency of uric phosphorus, urea nitrogen and uric acid is good in the healthy group, while the consistency of uric potassium, chlorine and acid is good in the lithiasis group; the consistency of other indicators is not good. Morning urinary biochemistry shows a better predictive value of lithiasis risks than 24-hour urinary biochemistry. Key words: Urinary lithiasis; Morning urinary biochemistry; 24-hour urinary biochemistry; Consistency; Bland-Altman analysis