Restricted intraindividual urinary iodine concentration variability in nonfasting subjects.
OBJECTIVE
Individual urinary iodine concentration (UIC) reflects iodine intake over a short time prior to sampling. Since eating habits are relatively constant in single subjects, UIC should be relatively constant in a given individual. The aim of our study was to verify this hypothesis by assessing UIC in repeated single urine samples from a group of healthy subjects.


METHODS
A prospective sequential investigation was performed in 131 volunteer health workers or students recruited in our University hospital.


METHODS
Single urine samples were taken in a nonfasting state, between 0900 and 1100 hours. Group 1 was composed by 131 subjects who collected one urine sample. Group 2 was composed by 11 subjects of the group 1, who collected multiple repeated urine samples (as a whole 158 urine samples, mean 14 samples each). UIC mean+/-s.d., median and coefficient of variation (CV%) was measured in both groups.


RESULTS
Interindividual UIC variation was wide, UIC ranging from 21 to 382 microg/l, mean 136+/-84 microg/l, median 124 microg/l, CV 62%. Also in the 11 subjects repeatedly sampling there were considerable differences among individual UIC average levels (ranging from 37+/-15 to 221+/-91 microg/l). However, in this second group, the intraindividual variation was considerably restricted (CV% 36).


CONCLUSIONS
The present study shows that in a nonfasting state in mid-morning UIC is more stable from day to day in a single subject, depending on his eating habits, than in various subjects. Thus, a single urine sample even in nonfasting state may give some rough information about the individual's iodine status.
Busnardo
B
B
Endocrinology Unit, Department of Medical and Surgical Sciences, University of Padua, Padua, Italy. benedetto.busnardo@unipd.it
Nacamulli
D
D
Zambonin
L
L
Mian
C
C
Piccolo
M
M
Girelli
M E
ME
D000328:Adult; D015415:Biomarkers / Q000652:urine; D005247:Feeding Behavior / Q000502:physiology; D005260:Female; D006042:Goiter / Q000175:diagnosis / Q000652:urine; D006304:Health Status; D006801:Humans; D007455:Iodine / Q000172:deficiency / Q000652:urine*; D008297:Male; D008875:Middle Aged; D019518:Postprandial Period; D011446:Prospective Studies
D015415:Biomarkers; D007455:Iodine