Boehm G, Wiener M, Schmidt C, Ungethüm A, Ungethüm B, Moro G
Centre for Infant Nutrition to Prevent Illnesses in Adult Life, Milan, Italy.
Acta Paediatr. 1998 Mar;87(3):339-43. doi: 10.1080/08035259850157435.
To establish adequacy of urine collection times shorter than 24h in the metabolic monitoring of low birthweight infants, we collected urine for 24 h in 39 LBW infants during the third and fourth week of life. All urine voidings over the 24-h period were separately collected, the volume of each sampling and the time of voiding were recorded, and 20% of the volume was removed for pooling. All individual and pooled samples were analysed for total nitrogen, urea and ammonia, alpha-amino nitrogen, creatinine, sodium, potassium, calcium and phosphorus, and for each compound the ratio to 1 mol creatinine was established. Individual sample results were "pooled" to obtain 3-, 6- and 12-h period excretion and than related to the 24-h excretion as measured in the pooled 24-h sample. As the volume of urine obtained in any 6-h collecting period depended on the time of sampling (06:00-12:00 h, 17.5+/-3.1% of total; 12:00-18:00 h, 31.6+/-5.1% of total; 18:00-24:00 h, 25.6+/-3.1% of total; and 0:00-06:00h, 25.3+/-2.9% of total), calculations were based on samples obtained from 18:00 to 06:00 h. The correlation between results of 3- and 24 h-collection periods was weakest, while results of the 6-h collection correlated highly with the total daily excretion (r = between 0.82 and 0.93 for the different compounds) and the correlation was only slightly better when the 12-h collection period was considered. The correlation between the mean molar substrate/creatinine ratio of all individual samples of a 24-h collecting period and the and total daily excretion of the respective substrate was weaker (r = between 0.46 and 0.76 for the different compounds) than the correlation between the results of a 6-h collecting period and the daily excretion is not as stable than in later life. The data indicate that 6-h urine sampling may be sufficient for metabolic monitoring of LBW infants. By contrast, urinary substrate/creatinine ratios are not good markers of the daily excretions of the respective substrate during the first weeks of life.
为确定在低出生体重儿代谢监测中收集短于24小时尿液样本的充足性，我们在39名低出生体重儿出生后第三和第四周收集了24小时尿液。24小时内的所有排尿均单独收集，记录每次采样的尿量和排尿时间，并取出20%的尿量用于混合。对所有个体样本和混合样本进行总氮、尿素和氨、α-氨基氮、肌酐、钠、钾、钙和磷的分析，并确定每种化合物与1摩尔肌酐的比值。将个体样本结果“合并”以获得3小时、6小时和12小时时间段的排泄量，然后与混合的24小时样本中测得的24小时排泄量相关联。由于在任何6小时收集时间段内获得的尿量取决于采样时间（06:00 - 12:00时，占总量的17.5±3.1%；12:00 - 18:00时，占总量的31.6±5.1%；18:00 - 24:00时，占总量的25.6±3.1%；0:00 - 06:00时，占总量的25.3±2.9%），计算基于18:00至06:00时获得的样本。3小时和24小时收集时间段结果之间的相关性最弱，而6小时收集结果与每日总排泄量高度相关（不同化合物的r值在0.82至0.93之间），考虑12小时收集时间段时相关性仅略好一些。24小时收集时间段内所有个体样本的平均摩尔底物/肌酐比值与相应底物的每日总排泄量之间的相关性较弱（不同化合物的r值在0.46至0.76之间），不如6小时收集时间段结果与每日排泄量之间的相关性稳定，且不如后期生活中稳定。数据表明，6小时尿液采样可能足以用于低出生体重儿的代谢监测。相比之下，尿液底物/肌酐比值在出生后第一周内并非相应底物每日排泄量的良好指标。
