Variations in the Urinary Iodine Concentration and Urinary Iodine/Creatinine Ratio among Preschool Children
Dong Sung AnRui YangYuping DuXuan WangYing YangWenxing GuoJunhong YangDong-Mei MengWeiwei GaoJiayi ZhangWen ChenWanqi Zhang
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Variations in different urinary measurements for evaluating iodine status are concerning to clinicians and researchers. The present study aimed to analyze the interindividual and intraindividual variations in the urinary iodine concentration (UIC) and urinary iodine/creatinine (UI/Cr) ratio and evaluate their application in assessing the iodine nutrition of preschool children. Four repeated spot urine samples were collected from 163 children at different times within one day. The urinary iodine concentration (UIC) and urinary creatinine concentration (UCr) were measured, and the UI/Cr ratio was calculated. The UIC ( < 0.001) and urinary iodine/creatinine ratio ( = 0.019) of multiple measurements were significantly different. The UIC of morning urine was highest (99.83 μg/L) and then gradually decreased with collection time ( < 0.001). In contrast, the UI/Cr ratio of morning urine samples increased with collection time. By computing the mean intraindividual and interindividual coefficients of variance (CV), the intraindividual variation of the UI/Cr ratio (68%) was significantly lower than that of the UIC (86%). Nevertheless, the interindividual variation was lowest in the UIC (78.62%) of morning urine. In addition, the UIC and UI/Cr ratio showed moderate correlations (r = 0.52, < 0.001), with kappa values of 0.42 in assessing iodine nutrition. The UIC of morning urine samples taken at 8:00–10:00 am was perhaps more stable and reliable in evaluating the iodine nutrition of preschool children at the population level. The UI/Cr ratio showed lower intraindividual variation and may be more suitable for assessing individual iodine nutrition.Keywords:
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Abstract Background and Aims In daily clinical practice, individual-level sodium (Na) intake is often estimated by measuring Na excretion in a single 24h urine collection, but long-term Na balance studies indicate that 7 consecutive 24h urine collections are needed. However, this approach is not feasible in clinical settings. In this study, we investigate whether the use of repeated spot urine sampling is an appropriate alternative for repeated 24h urine collections. Method We performed a post-hoc analysis of a metabolic ward study in 8 healthy male adults who consumed a 7-day diet with a fixed amount of Na (200 mmol/d). Urine was collected in four daily intervals: 7-13h, 13-19h, 19-23h and 23-7h. After reaching steady state, we estimated Na intake with 1 and 3 consecutive 24h urine collections and 3-day spot urine sampling, using the Kawasaki formula with measured 24h urine creatinine excretion. Results: On day 5, mean 24h Na excretion matched intake, indicating that steady state was achieved (Fig A). Mean and standard deviation of absolute differences between estimated and measured Na intake (ΔNa) for each method were: 18.8 ±14.6 mmol (3 x spot urine 7-13h), 32.3 ±18.7 mmol (3 x spot urine 13-19h), 74.6 ±30.0 mmol (3 x spot urine 19-23h), 28.2 ±19.8 mmol (3 x spot urine 23-7h), 29.8 ±23.9 mmol (1 x 24h urine) and 22.9 ±11.3 mmol (3 x 24h urine) (Fig B). With the exception of the 19-23h spot urine collection period, the accuracy of 3-day spot urine sampling did not significantly differ from accuracy of 1 and 3 consecutive 24h urine collections. When combining the pre-night and morning spot urine collections (19-7h), the accuracy of the estimation did not improve (ΔNa 28.7 ±19.6 mmol). Conclusion 3-day spot urine sampling did not perform significantly different than 1 and 3 24h urine collections for estimation of individual-level Na intake. Adequately powered studies need to confirm whether repeated spot urine sampling is an accurate and low burden alternative to repeated 24h urine collections.
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Dary-to-day variation of urine 90Sr may produce error in the assessment of body 90Sr by urinalysis. Based on the good correlation between urine 90Sr and Ca, the range of the day-to-day variation of urine 90Sr was inferred from that of calcium, which was obtained from the analysis of about 50 to 100 urine samples per person in seven volunteers. From the frequency dstribution curves of urine calcium, it was concluded that 90per cent of the daily urine 90Sr would be involved in the range from 0.4 to 2.0 times the mean value. Therefore, if the assessment of body 90Sr is made from only one urinary excretion level, the estimated body burden will probably be in the range between 0.4 and 2 times the correct value.
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An automated method for determining total estrogen in 24-hour urine was reported. The "estrogen-creatinine quotient" was computed in order to make the results of collective errors as independent as possible. This numerical value also makes possible comparative studies of 24-hour urine and morning urine (6:00 a.m.) as well as of urine specimens taken every two hours between 6:00 a.m. and 6:00 p.m. A total of 1000 analyses were made in 110 pregnant women; in addition, 82 daily profiles were studied. A high correlation was found between the E/C from 24-hour urine and from morning urine. In approximately two thirds of the cases, the deviation between morning urine and 24-hour urine did not exceed 10%. In the daily profiles, however, a wide variation in the daily rhythmn of some patients could be observed. According to our results, the determination of E/C in morning urine is well suited as a screening method for quick detection of estrogen elimination, particularly in high risk pregnancies.
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Objective To study the feasibility of the urine iodine level at different times instead of the morning urine.Methods Collect the urine samples of the 117 pupils in the morning and at 8∶00?11∶00?13∶30?16∶00 and compare the difference of the urine iodine level at different time.Results There were significant differences between any two samples but between the samples in the morning and at 13∶30. There were correlations between the morning urine sample and the other ones.Conclusions Only the iodine level of urine samples at 13∶30 could replaced that of the morning urine samples. It is incorrect that the iodine nourishment condition was reflected by the iodine level of urine sample at random.
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The excretion of urinary protein was evaluated in 62 owl monkeys using timed urine collections. The ratio of urine protein to urine creatinine concentrations (Up/c) was determined for each monkey. Linear regression analysis was used to calculate the correlation between that ratio and urine protein (mg/dl) and 24-hour urinary protein loss (mg/kg). The coefficient of determination for Up/c to urine protein and 24-hour urinary protein loss was significant (P less than or equal to 0.0001). Determination of the Up/c in a urine specimen was found to be an acceptable diagnostic technique for detection and quantitative estimation of proteinuria.
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1. At the present time there is no method whereby the completeness of 24 h urine collections can be accurately assessed when clinical studies are undertaken. The suitability of 4-aminobenzoic acid (PAB) given with meals as a marker for completeness of urine collections was therefore investigated. 2. When a single dose of 80 mg of PAB was given to four volunteers 93% was recovered in the urine in 5 h. 3. Eight volunteers living in a calorimeter, where complete urine collection could be guaranteed, were given various doses of PAB divided up throughout the day. 88 ± 5% was excreted in the urine over a 24 h period. Urine excretion and oral dose were directly related. 4. Thirty-three reliable free-living volunteers eating their normal diet took 80 mg of PAB with meals (240 mg/day). Mean urine recovery over the 24 h period was 223 ± 9 mg, or 93 ± 4% of the administered dose. The range in individual recovery from maximum to minimum was 15%, compared with 75% for creatinine excretion per kg fat-free mass. 5. PAB is a safe marker of the completeness of 24 h urine collections. Any collection containing less than 205 out of 240 mg (85%) of PAB, given as 80 mg with each of three meals, is probably incomplete.
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Abstract Urinary B1 (vitamin B1) excretion is commonly determined in 24‐hr urine specimens to obtain an estimate of nutritional status. The aim of our study was to investigate whether B1 in random urine specimens, corrected for the urine creatinine (Cr), can be substituted for B1 in 24‐hr urines. Collection of such hour urines is often fraught with errors; an alternative method is described here. All urine specimens voided over 24 hr were collected from 32 healthy adults as were the first‐morning urines from 30 healthy Japanese women. The B1 excretion was expressed as the ratio of B1 to Cr. Although the B1 excretion was expressed as the B1/Cr ratio, the B1 excretion varied with the urine volume and the time of urine collection. The B1/Cr ratio in random urine specimens not collected at a fixed time may mislead the evaluation of the nutritional status. We found that the B1/Cr ratio in the first‐morning urine correlated significantly with the ratio in 24‐hr urines ( r =0.970, P <0.001) and also with the concentration of total B1 (B1 plus its phosphate esters) in whole blood ( r =0.733, P <0.001). We conclude that the B1/Cr ratio in 24‐hr urines could be estimated by measuring the ratio in the first‐morning urine. J. Clin. Lab. Anal. 22:291‐294, 2008. © 2008 Wiley‐Liss, Inc.
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Creatinine concentration is commonly used to verify the authenticity of urine specimens submitted for illicit drug screening. This study evaluated creatinine screening of donor urine specimens as a tool for detecting substituted and/or tampered specimens. The study carried out creatinine assay of animal urine, fruit juices, and urine from creatine-supplemented subjects by a modified version of the Jaffe reaction. All specimens were analyzed for creatinine concentration in a chemistry-immuno analyzer. Results showed that urine specimens from common domestic pets, including cats, dogs, and horses, have creatinine values similar to normal human values. Most fruit juices tested contained no detectable creatinine, and the few that did showed poor "urine" chemical integrity. Creatine supplementation by donors was found not to provide an effective means of elevating creatinine concentration in urine when attempting to flush out water-soluble drugs in the body. Thus, the assay for creatinine proved useful for the detection of some but not all adulterated urine specimens.
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Objective: To discuss the probability of using the second morning urine in place of ten items of the first morning urine analysis.Methods: To select the inpatients mid-stream urine liquid at 5∶00～6∶00 in the morning then sent it to the lab in time and made the ten items of urine test,after the urine liquid was laid for three hours , then made the ten items of urine test again;at 8∶00～9∶00, to take the mid-stream urine liquid again and made a test then compared the difference of them.Results: After the first morning urine was laid for 3 hours, among the ten items of urine's assay, the effect of GIU ?PRO and WBC heightened (P0.05～0.001), among the ten items of the second morning urine analysis the effect of GIU. WBC heightened distinctly (P0.05). The effect of the other test items were not difference in statistics (P0.05). Conclusion: Useing the second morning urine heighted the ratio of masculine of some test items, suggest to take the second morning urine and make the ten items of the first morning urine analysis.
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