Table 2.

Saliva concentrations of phosphorus and urea in healthy volunteers: comparisons of standard samples with mid‐morning samples and frozen/thawed samples (n = 15, mean ± SEM)

	Standard samples	Mid‐morning samples	P for difference between samples	R between samples
Phosphorus, mmol/L	5.89 ± 0.73	4.24 ± 0.62	.095	.786*
Urea, mmol/L	5.17 ± 0.81	4.07 ± 0.45	.009	.822*
	Standard samples	Frozen/thawed samples
Phosphorus, mmol/L	5.45 ± 0.56	4.77 ± 0.51	.093	.742*
Urea, mmol/L	5.24 ± 0.71	4.93 ± 0.66	.200	.865*

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

Mid‐morning samples: non‐stimulated fresh saliva collected with the use of a synthetic swap in the morning three hours after the completion of breakfast.

Frozen/thawed samples: non‐stimulated saliva collected with the use of a synthetic swap early in the morning after an overnight fast.

* P < .001, ** P < .01.