|
|
The Iodine Group | |
|
Home | Orthoiodosupplementation | Body | Disease | Special | Overviews |
||
|
|
Christiansen, Rasmussen
Age- and sex-adjusted iodine/creatinine ratio. A new standard in epidemiological surveys? Evaluation of three different estimates of iodine excretion based on casual urine samples and comparison to 24 h values.Knudsen N, Christiansen E, Brandt-Christensen M, Nygaard B, Perrild H. Eur J Clin Nutr. 2000 Apr;54(4):361-3. [abstract only]
"OBJECTIVE: The most accurate way to measure urinary iodine excretion in epidemiological surveys is still debated. We propose a new principle of estimating iodine excretion based on casual urine samples.
MATERIAL AND METHODS: A total of 123 24 h urine samples and corresponding casual urine samples were collected from 31 subjects. Iodine excretion was expressed as 24 h iodine excretion and three different estimates: iodine concentration in the casual sample, iodine/gram creatinine in the casual sample, and the new principle-iodine/creatinine ratio in the casual sample, adjusted for expected creatinine excretion of the individual.
RESULTS: All three estimates based on casual urine samples correlated significantly to 24 h values with a r (Pearson) of 0.37 for iodine concentration, 0. 61 for iodine/creatinine ratio and 0.62 for the age- and sex-adjusted iodine/creatinine ratio. The median iodine excretion in the entire group was 143 microg/day in 24 h samples, 87 microg/l as iodine concentration, 77 microg/g creatinine as iodine/creatinine ratio and 126 microg/day as age- and sex-adjusted iodine/creatinine ratio.
CONCLUSION: Age- and sex-adjusted
iodine/creatinine ratio is a more accurate and unbiased estimate of
iodine excretion in epidemiological surveys of adults than the two
most frequently used estimated: iodine concentration and iodine/gram
creatinine, as these two estimates may introduce a bias depending on
the composition of the investigated group. The adjusted
iodine/creatinine ratio is superior to the other estimates, especially
when individual estimates of 24 h iodine excretion is required or
cohorts of selected groups are investigated."
Day-to-day and within-day variation in urinary iodine excretion.Rasmussen LB, Ovesen L, Christiansen E. Eur J Clin Nutr. 1999 May;53(5):401-7. [abstract only]
"OBJECTIVE: To examine the day-to-day and within-day variation in urinary iodine excretion and the day-to-day variation in iodine intake.
DESIGN: Collection of consecutive 24-h urine samples and casual urine samples over 24h. SETTING: The study population consisted of highly motivated subjects from our Institute. SUBJECTS: Study 1: Ten healthy subjects (seven females and three males) aged 30-46 y. Study 2: Twenty-two healthy subjects (9 males and 13 females) aged 30-55 y. METHODS: Study 1: 24-h urine samples were collected for four consecutive days. Study 2: Each urine voided over 24 h was collected into separate containers. In both studies dietary records were kept. MAIN OUTCOME MEASURES: Twenty-four-hour urinary iodine excretion, 24-h urinary iodine excretion estimated as I/Cr*24 h Cr and as a concentration in casual urine samples.
RESULTS: Study 1: Both iodine excreted in 24-h urine and iodine intake varied from day-to-day. Iodine excretion correlated with iodine intake (=-0.46, P=0.01). Iodine intake (mean 89 +/- 6.5 microg/d) was not significantly different from iodine excretion (mean 95 +/- 5.3 microg/d). Study 2: Twenty-four hour iodine excretion estimated as I/Cr*24 h Cr from the morning urine sample was significantly lower than actual 24-h iodine excretion, whereas 24-h iodine excretion estimated as I/Cr*24 h Cr from the first sample after the morning sample and the last sample before the subjects went to bed was not significantly different from actual 24-h iodine excretion. Twenty-four-hour urine excretion estimated as a concentration was lower than actual 24-h iodine excretion in casual urine taken at any time of the day.
CONCLUSIONS: For determination of iodine status in
an individual, more than one 24-h urine sample must be used. The use
of the I/Cr ratio in casual urine samples is a usable measure of
iodine status if corrected for the age- and sex-adjusted 24-h
creatinine excretion. Further, the study suggests that fasting morning
urine samples would underestimate iodine status in this population." |
|
Home | Orthoiodosupplementation | Body | Disease | Special Topics | OverviewsThe Iodine Group | Books | Disclaimers | Contact Us | Search
|
||
