Open AccessValidation of daily urinary creatinine excretion measurement by muscle‐creatinine equivalence
Author(s) -
Iacone Roberto,
D'Elia Lanfranco,
Guida Bruna,
Barbato Antonio,
Scanzano Clelia,
Strazzullo Pasquale
Publication year - 2018
Publication title -
journal of clinical laboratory analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.536
H-Index - 50
eISSN - 1098-2825
pISSN - 0887-8013
DOI - 10.1002/jcla.22407
Subject(s) - creatinine , bioelectrical impedance analysis , linear regression , muscle mass , medicine , coefficient of variation , urology , mathematics , chemistry , statistics , body mass index
Background Twenty‐four‐hour urinary creatinine excretion (24h UC rE) is strongly correlated with skeletal muscle mass ( SMM ). This study suggests how to exploit the power of the SMM ‐24h UC rE correlation to assess the accuracy of 24h UC rE measurement. Methods Four hundred and sixty‐six men, a subgroup of participants in the 2002‐2004 follow‐up examination of the Olivetti Heart Study, performed a 24‐h urine collection to measure 24h UC rE and underwent bioelectrical impedance analysis to evaluate SMM . Linear regression analysis between 24h UC rE and SMM was used to calculate the muscle‐creatinine equivalence and to develop an equation to predict the 24h UC rE depending on SMM . The accuracy of the 24h UC rE measurement was assessed using the change in the SMM ‐24h UC rE correlation coefficient upon variation in the percentage deviation (% D ) between the measured and predicted 24h UC rE. Results The calculated muscle‐creatinine equivalence was 1 g of 24h UC rE = 22.73 kg of SMM . The % D s and the corresponding SMM ‐24h UC rE correlation coefficients were as follows: % D = 3.0, r = .997; % D = 4.7, r = .989; % D = 8.1, r = .963; % D = 10.5, r = .940; % D = 12.6, r = .909; % D = 18.9, r = .825; % D = 25.8, r = .707; % D = 33.5, r = .595; % D = 41.4, r = .453. Conclusion The increase in % D corresponds to a reduced correlation between muscle mass and creatinine excretion, which indicated a poor performance in the measurement of the 24h UC rE. For studies on single individuals, where small variations in 24h UC rE could be significant, a % D up to 12.6% is suggested; on the other hand, a wider % D interval could be acceptable for population studies.