PTH and chronic kidney disease: occurred at pH 6.8 or 7.0, [P]DCT was the sole determinant of [Ca++]DCT; [PTH] increased to abnormal levels over a wider and more plausible range of [Ca++]DCT, and a continuous hyperbolic relationship between [PTH] and [Ca++]DCT emerged if CKD and CTRL were considered together (Figs 3 and 4).