Salivary Phosphorus and Level of Kidney Function
Salivary Phosphorus and Level of Kidney Function
The specific purpose of this study is to describe the relationship between salivary
 phosphorus and kidney function, specifically as it relates to serum phosphorus, FGF23, PTH,
 vitamin D status and urinary excretion of phosphorus.
Previous studies have demonstrated that salivary phosphate levels are elevated in patients
 with chronic kidney disease and that there is a direct and linear correlation between serum
 phosphorus and salivary phosphorus. However, data regarding the relationship between salivary
 phosphate levels and stage of kidney disease (estimated glomerular filtration rate (eGFR) is
 lacking; as such, this study seeks to examine that relationship.

 There is a normal circadian rhythm to serum phosphorus with a mid-afternoon peak at
 approximately 3 PM and a nadir at approximately 7-11 AM. Furthermore it has been demonstrated
 that a fasting serum phosphorus level at 8 AM is NOT indicative of 24 hour mean serum
 phosphorus. Thus the relationship between salivary phosphorous and serum phosphorus may vary
 over the course of the day.

 This is a single-center study in which saliva, urine, and serum will be collected at two time
 points in a minimum of 105 subjects with various degrees of renal function (not on dialysis).
 Assignment to the renal group will be based upon the Visit 2 estimated glomerular filtration
 rate value. Enrollment in each group will continue at random until the target of 15 subjects
 per group is achieved. It is possible that an individual group may exceed the target
 enrollment number as their assignment will occur retrospectively.

 All subjects will be required to have their morning assessment conducted between the hours of
 7AM and 11AM. Clinical chemistry, serum phosphorus, intact parathyroid hormone(iPTH), plasma
 fibroblast growth factor 23 (FGF-23),serum 1,25 di-hydroxyvitamin D, serum 25-OH vitamin D,
 and a spot urine will be collected. A 24-hour urine sample will also be collected.

 Passive and stimulated salivary collection will occur. The salivary collection must occur in
 a fasting state with nothing to eat or drink for at least 90 minutes prior to the collection.

 Subjects will be permitted to leave the facility. They will be instructed to consume a lunch
 of their choice between the hours of 1100AM and 1200PM. They will be instructed to eat
 nothing after 1200PM. Subjects will return to the clinic for Visit 3 as directed by the study
 staff. Visit 3 will be conducted between 1PM and 4PM. Laboratory assessments, salivary
 collections, and spot urines will be collected at Visit 3. A dietary recall of intake at
 Visit 2 and 3 will also be completed.
Inclusion Criteria:

 -  Men or women greater than 18 years of age.

 -  The subject has voluntarily signed and dated the most recent informed consent form
 approved by an Institutional Review Board (IRB).

 Exclusion Criteria:

 -  Receiving hemodialysis.

 -  Receiving or has received an investigational product (or is currently using an
 investigational device) within 28 days prior to Visit 2.

 -  Evidence of active and clinically significant infection at Visit 2.

 -  Dental work within 48 hours prior to Visit 2.