Determination of hydroxylysine in urine.

A new method for colorimetric determination of urinary hydroxylysine is described. Approximately one-hundredth of human urine collected for 24 hr was diluted to 25 ml and titrated to pH 2.0 with 2 hcl, and then subjected to column chromatography on Dowex 50 X 4 (H+ form). Amino acids were eluted from the column with 1.5 N NH4OH. Hydroxylysine in the elute with 1.5 N NH4OH was separated from the other amino acids, especially from serine and threonine, by preparative paper chromatography. The paper corresponding to hydroxylysine was cut and eluted with water. An aliquot of the eluate with water was oxidized by sodium metaperiodate, and formaldehyde liberated from hydroxylysine was assayed by chromotropic acid reagents, after removing periodate and iodate with Dowex 1 X 8 (formate form). Excretion rate of hydroxylysine in urine of adults was shown to be approximately 110 mumoles per day.