Rationale to reduce calcium intake in adult patients with chronic kidney disease.

PURPOSE OF REVIEW: Calcium is an essential ion for the maintenance of normal bone health and physiologic functions. The extracellular and intracellular levels of calcium are maintained through hormonal regulation called homeostasis. Balance, the net intake minus excretion of calcium, is maintained by hormonal regulation of intestinal absorption and fecal/urinary excretion. Homeostasis and balance are disconnected in patients with chronic kidney disease (CKD). The purpose of this review is to understand how calcium homeostasis and balance are impaired in CKD.

RECENT FINDINGS: Two formal calcium balance studies have found that an oral intake of 800-1000 mg of calcium in adults with CKD leads to neutral calcium balance, whereas amounts greater than that lead to positive calcium balance. In patients with CKD, the main determinant of positive calcium balance is the intake and the lack of urinary calcium excretion.

SUMMARY: Calcium balance is different in patients with advanced CKD compared with patients without CKD. Thus, the oral intake of calcium in the form of diet and binders should not exceed 800-1000 mg/day to achieve neutral calcium balance in adult patients with CKD stages 3b/4.