... 368regulation-calcitriolbone, 372 kidney, 373 small intestine, 373 regulation-PTHbone, 372 kidney, 372 small intestine, 372 regulation-phosphatoninsFGF-23, 368, 375 – 376 sFRP-4/MEPE/FGF -7 , 377 renal ... 372 relationship with ECF ion-ized Ca2+, 183, 312pH to proton concentration (nM/L) conversion, 192pheochromocytoma, 325, 331phosphatoninsFGF-23, 368, 375 – 376 sFRP-4/MEPE/FGF -7 , 377 phosphorus. ... 48 and true hyponatremia, 71 ENac blockers, 116. Seealso amiloride; triamtereneeplerenone, 1 07, 116, 1 17, 126, 163, 243, 272 equationsGoldman-Hodgkin-Katzequation, 1 37, 138Henderson-Hasselbalchequation,...