While the circadian rhythm of serum phosphorus in healthy individuals has been described, no data exists on the circadian rhythm of salivary P, nor has the circadian rhythm of serum P been described in subjects with moderate kidney disease exposed to various levels of dietary P exposure. In recent years, saliva has been found to be a good indicator of the plasma level of various substances, one of which being phosphorus. Specifically, increased salivary P excretion has been reported in patients with CKD. Daily salivary secretion volume ranges between 500 - 700 mL/day, therefore salivary P has recently been established as a previously unaccounted for source of phosphorus, contributing a conservative estimate of 366 mg/day and 2500 mg/week of immediately bioavailable phosphorus.