[Variations in the excretion of N-acetyl-glucosaminidase in the first year of life].

We have studied 122 patients, all younger than 12 months of age, to whom we check the N-acetylglucosaminidase/creatinine (NAG/creatinine) ratio in the first morning urine. The NAG/creatinine values were decreasing with age increase of the patients, being significantly different (p less than 0.001) in the younger 3 months of age comparative with the older than six months of age. The NAG/creatinine values were inversely correlated with age, height and weight. We have made normal values percentils of the NAG/creatinine ratio for each age group.