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Evidence for Systematic Temporal Variation In 24‐Hour Urinary Creatinine Excretion
Author(s) -
RANSIL BERNARD J.,
GREENBLATT DAVID J.,
KOCHWESER JAN
Publication year - 1977
Publication title -
the journal of clinical pharmacology
Language(s) - Uncategorized
Resource type - Journals
SCImago Journal Rank - 0.92
H-Index - 116
eISSN - 1552-4604
pISSN - 0091-2700
DOI - 10.1002/j.1552-4604.1977.tb04596.x
Subject(s) - creatinine , standard deviation , pooling , mathematics , urinary system , statistics , medicine , zoology , biology , artificial intelligence , computer science
Five hundred fifty-seven 24-hour urinary creatinine specimens from eight healthy males collected in six-day sequences separated by two- to ten-week intervals over six to ten months were analyzed for factors contributing to the large observed standard deviation and range (14% and 50% of the total mean, respectively). Subject means correlated significantly with weight and surface area. Between-sequence differences were significantly greater than within-sequence differences in all subjects. Statistically significant linear and/or curvilinear time dependences were found in each subject. Elimination of subject variation and pooling yielded one cycle of a biphasic function, approximately 12 months in duration, oscillating about the mean with an amplitude approximately 6% of the mean; the maximum and minimum exhibited a seasonal correspondence. Upper limits to sources of eror are estimated as measurement +/- 3%, biological +/- 6%, mixed biologic-temporal +/- 6%, and random +/- 5%.