Figure 4: Comparison of assays. Highly sensitive colorimetric assays for urine calcium and creatinine were compared with assays done by the clinical lab. Line shows the least-squares line. Left panel, assays for urine calcium. There is good correlation between the assays (n=52, r2=0.901, p< 0.0005), however, 23 samples were at or below the limit of detection in the clinical lab. Right panel, assays for urine creatinine. There is again good correlation (n=52, r2=0.881, p< 0.0005), however, 9 samples were at or below the limit of detection in the clinical lab.