BACKGROUND: Alpha-1-microglobulin (A1M) is a low molecular weight protein that can be measured in urine and used as a marker for tubular function, assuming that the normal variability within and between individuals is known. The aims of this study were to investigate this variability, to find the optimal way of sampling and quantifying A1M in spot urine samples to reflect the 24 h excretion and to examine storage stability. Method. Timed urine specimens were collected from 29 healthy volunteers at fixed time points over 24 h on two separate days. Volumes, creatinine and specific gravity were determined. All samples were analysed with a commercial ELISA for A1M. RESULTS: We found a clear diurnal variation in A1M excretion rate and a gender effect (higher in males). The excretion rate was higher in the daytime, with high urinary flow, compared to overnight values. A1M excretion in spot urine samples was highly correlated with the 24 h excretion at all times except 22:00 in male subjects. Urinary A1M adjusted for creatinine concentration correlated well with the 24 h excretion. Variability within individuals was only 20% of the total variability in 24 h A1M excretion, but 43% in first morning urine. Expressed as CV, the intra-individual variability (between days) was 29% in 24 h excretion. CONCLUSION: We conclude that diurnal variation and gender should be taken into account when comparing groups. Moreover, in spot samples (e.g. first morning samples) adjustment of A1M for creatinine or specific gravity is a reliable alternative to 24 h urine.
BACKGROUND:Alpha-1-microglobulin (A1M) is a low molecular weight protein that can be measured in urine and used as a marker for tubular function, assuming that the normal variability within and between individuals is known. The aims of this study were to investigate this variability, to find the optimal way of sampling and quantifying A1M in spot urine samples to reflect the 24 h excretion and to examine storage stability. Method. Timed urine specimens were collected from 29 healthy volunteers at fixed time points over 24 h on two separate days. Volumes, creatinine and specific gravity were determined. All samples were analysed with a commercial ELISA for A1M. RESULTS: We found a clear diurnal variation in A1M excretion rate and a gender effect (higher in males). The excretion rate was higher in the daytime, with high urinary flow, compared to overnight values. A1M excretion in spot urine samples was highly correlated with the 24 h excretion at all times except 22:00 in male subjects. Urinary A1M adjusted for creatinine concentration correlated well with the 24 h excretion. Variability within individuals was only 20% of the total variability in 24 h A1M excretion, but 43% in first morning urine. Expressed as CV, the intra-individual variability (between days) was 29% in 24 h excretion. CONCLUSION: We conclude that diurnal variation and gender should be taken into account when comparing groups. Moreover, in spot samples (e.g. first morning samples) adjustment of A1M for creatinine or specific gravity is a reliable alternative to 24 h urine.
Authors: Jean F Wyman; Jincheng Zhou; D Yvette LaCoursiere; Alayne D Markland; Elizabeth R Mueller; Laura Simon; Ann Stapleton; Carolyn R T Stoll; Haitao Chu; Siobhan Sutcliffe Journal: Neurourol Urodyn Date: 2020-01-09 Impact factor: 2.696
Authors: Lars Barregard; Peter Møller; Trine Henriksen; Vilas Mistry; Gudrun Koppen; Pavel Rossner; Radim J Sram; Allan Weimann; Henrik E Poulsen; Robert Nataf; Roberta Andreoli; Paola Manini; Tim Marczylo; Patricia Lam; Mark D Evans; Hiroshi Kasai; Kazuaki Kawai; Yun-Shan Li; Kazuo Sakai; Rajinder Singh; Friederike Teichert; Peter B Farmer; Rafal Rozalski; Daniel Gackowski; Agnieszka Siomek; Guillermo T Saez; Concha Cerda; Karin Broberg; Christian Lindh; Mohammad Bakhtiar Hossain; Siamak Haghdoost; Chiung-Wen Hu; Mu-Rong Chao; Kuen-Yuh Wu; Hilmi Orhan; Nilufer Senduran; Raymond J Smith; Regina M Santella; Yali Su; Czarina Cortez; Susan Yeh; Ryszard Olinski; Steffen Loft; Marcus S Cooke Journal: Antioxid Redox Signal Date: 2013-01-31 Impact factor: 8.401
Authors: Stefan A Ljunggren; Liam J Ward; Pål Graff; Anders Persson; Malin Leijon Lind; Helen Karlsson Journal: PLoS One Date: 2021-03-18 Impact factor: 3.240