Renal reabsorption of Ca²⁺. About 70% of filtered Ca²⁺ is being reabsorbed via the paracellular route in the proximal tubular and about 25% in the loop of Henle. About 5%–10% of filtered Ca²⁺ is reabsorbed in the distal tubules (distal convoluted tubule, DCT, and connecting tubule, CT) via the transcellular route as follows: (1) luminal absorption occurs through TRPV5; (2) transport of Ca²⁺ to the basolateral membrane is facilitated by calbindin-D_28K; and (3) basolateral exit occurs via the PMCA pump or the Na⁺/Ca⁺ exchanger NCX1 (SLC8A1). PTH, which is released following hypocalcemia, increases renal Ca²⁺ reabsorption by stimulation of the expression of TRPV5 and calbindin. The regulation of TRPV5 in the distal tubule plays an important role in the fine-tuning of the whole-body Ca²⁺ balance. Note that, in the human kidney, TRPV6 may play additional Ca²⁺-absorptive roles in the tubular system.