Table 1.

Saliva concentrations of phosphorus and urea in standard samples of healthy volunteers: blind duplicates, site of collection, and day‐to‐day variability (n = 15, mean ± SEM)

	Blind duplicates		P for difference between samples	R between samples
	First duplicate	Second duplicate
Phosphorus, mmo/L	5.59 ± 0.73	5.81 ± 0.75	.526	.994*
Urea, mmol/L	5.15 ± 0.72	4.90 ± 0.58	.615	.976*
	Site of collection
	Right vestibulum oris	Left vestibulum oris
Phosphorus, mmo/L	5.42 ± 0.65	5.19 ± 0.48	.467	.896*
Urea, mmol/L	5.10 ± 0.97	5.12 ± 0.79	.965	.887*
	Day‐to‐day variability
	First day	Second day
Phosphorus, mmol/L	5.44 ± 0.68	5.70 ± 0.74	.965	.606**
Urea, mmol/L	5.17 ± 0.76	4.88 ± 0.98	.371	.906*

Standard samples: non‐stimulated fresh saliva collected early in the morning after an overnight fast and with the use of a synthetic swap.

*P < .001, **P ≤ .01.