title: High (but not low) urinary iodine excretion is predicted by iodine excretion levels from five years ago.
abstract: BACKGROUND
  It has not been investigated whether there are associations between urinary iodine (UI) excretion measurements some years apart, nor whether such an association remains after adjustment for nutritional habits. The aim of the present study was to investigate the relation between iodine-creatinine ratio (ICR) at two measuring points 5 years apart.
  
  
  METHODS
  Data from 2,659 individuals from the Study of Health in Pomerania were analyzed. Analysis of covariance and Poisson regressions were used to associate baseline with follow-up ICR.
  
  
  RESULTS
  Baseline ICR was associated with follow-up ICR. Particularly, baseline ICR >300 μg/g was related to an ICR >300 μg/g at follow-up (relative risk, RR: 2.20; p < 0.001). The association was stronger in males (RR: 2.64; p < 0.001) than in females (RR: 1.64; p = 0.007). In contrast, baseline ICR <100 μg/g was only associated with an ICR <100 μg/g at follow-up in males when considering unadjusted ICR.
  
  
  CONCLUSIONS
  We detected only a weak correlation with respect to low ICR. Studies assessing iodine status in a population should take into account that an individual with a low UI excretion in one measurement is not necessarily permanently iodine deficient. On the other hand, current high ICR could have been predicted by high ICR 5 years ago.
authors: Institute of Community Medicine, University of Greifswald, Greifswald, Germany. till.ittermann@uni-greifswald.de
authors: Till
authors: T
authors: Ittermann
authors: Anke
authors: A
authors: Nautsch
authors: Carsten Oliver
authors: CO
authors: Schmidt
authors: Axel
authors: A
authors: Kramer
authors: Harald
authors: H
authors: Below
authors: Thomas
authors: T
authors: Remer
authors: Roland
authors: R
authors: Gärtner
authors: Henri
authors: H
authors: Wallaschofski
authors: Henry
authors: H
authors: Völzke
mesh_terms: D000328:Adult; D000368:Aged; D000465:Algorithms; D015415:Biomarkers / Q000652:urine; D015331:Cohort Studies; D003404:Creatinine / Q000652:urine; D003677:Deficiency Diseases / Q000453:epidemiology / Q000652:urine; D005260:Female; D005500:Follow-Up Studies; D005858:Germany / Q000453:epidemiology; D006042:Goiter / Q000453:epidemiology / Q000652:urine; D006306:Health Surveys; D006801:Humans; D007455:Iodine / Q000172:deficiency / Q000652:urine*; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D012306:Risk; D012727:Sex Characteristics; D055815:Young Adult
chemical_list: D015415:Biomarkers; D007455:Iodine; D003404:Creatinine