ABSTRACT
Objective To verify the application value of urinary iodine creatinine ratio in urinary iodine examination under different ways of collecting urine samples.Methods Totally 20 healthy adults were recruited and the urine samples were collected as each time random urine within 1 day,the 24 hour urine and morning urine within 5 successive days,respectively.Urinary iodine concentration and creatinine concentration in all urine specimens were determined.The coefficient of variation of urine iodine creatinine concentration ratio in each group was calculated.Paired t test was used to compare the urine iodine creatinine concentration ratio of 24 hour urine with the urine iodine creatinine concentration ratio of random urine and that of morning urine,respectively.Results The coefficient of variation of urinary iodine concentration values of random urine,morning urine and 24 hour urine samples within 1 d were 12.5％-57.4％,5.4％-26.0％,3.4％-16.6％,respectively,and the corresponding coefficient of variation of urinary iodine concentration The main distribution is around 30％,12％,and 8％.The coefficients of variation for random urine iodine creatinine concentration ratio within one day were 11.6％-36.1％,while most of the coefficients of variation were around 23％.In contrast,the coefficients of variation of morning urine and 24 hour urine within 5 days were 3.9％-16.8％ and 4.3％-12.7％ and most of them were at about 10％ and 7％.The difference of urinary iodine/creatinine concentration ratio between random urine,morning urine and 24 h urine sample was statistically significant (F =4.002,P ＜ 0.05).And the urine iodine creatinine concentration ratio of random urine were significantly different compared with that of 24 hour urine (P ＜ 0.05).On the other hand,there was also significant difference for the urine iodine creatinine concentration ratio of morning urine compared with that of 24 hour urine (P ＜ 0.05).Conclusions After adjusted with urinary iodine creatinine concentration ratio,the effect of urine concentration and dilution on urinary iodine concentration has reduced.The significance of two kinds of urine retention methods for random urine and morning urine in urine iodine detection is enhanced.But it's still not good enough to replace 24 hour urine.
ABSTRACT
Objective · To compare urine sample collection methods for measuring urinary concentrations of phenolic endocrine disrupting chemicals including bisphenol A (BPA),triclosan (TCS),and 4-n-nonylphenol (4-n-NP) in pregnant women.Methods· Urine samples were collected from women at late pregnancy by two methods:urine catheter and collection bag (n=176),urine collecting containers made of polypropylene (PP) (n=642).Urinary concentrations of BPA,TCS and 4-n-NP were measured with high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS)method.Confirmation experiment used PP containers,urine catheter and collection bags,as well as low-density polyethylene (LDPE) tubes and glass containers as both negative controls to collect urine samples from each of the 5 women.Results · Geometric mean (GM) of urinary BPA concentration collected by urine catheter and collection bags was 82.5 ng/mL (95％ CI 71.4-95.4 ng/mL),which was 63 times higher than that from PP containers (GM 1.3 ng/mL;95％ CI 1.3-1.5 ng/mL).Concentrations of urinary 4-n-NP and creatinine were similar between two collection methods.Confirmation experiment showed that urinary BPA concentration collected by urine catheter and collection bags was much higher than those collected by other three methods.Conclusion· In collection of urine samples for measuring phenolic chemicals,PP urine collection container as well as LDPE containers are adequate for use in epidemiologic studies,but urine catheter and collection bag is not.