Evaluation of variation of saliva iodine and recommendations for sample size and sampling time: Implications for assessing iodine nutritional status. Issue 5 (May 2021)

• Record Type: Journal Article
• Authors: Guo, Wenxing; Dong, Shuyao; Jin, Ya; Pan, Ziyun; Pearce, Elizabeth N.; Wu, Wen; Zhang, Ying; Chen, Wen; Zhang, Wanqi
• Is Part Of: Clinical nutrition. Volume 40:Issue 5(2021)
• Page Start: 3559
• Page End: 3566
• Publication Date: 2021-05
• Subjects: Saliva iodine -- Variation -- Sample size -- Sampling time -- Iodine nutritional status; SIC saliva iodine concentration -- 24-h UIC 24-hour urinary iodine concentration -- 24-h UIE 24-hour urinary iodine excretion -- UIC urinary iodine concentration -- UIE urinary iodine excretion -- WIC water iodine concentration -- ICP-MS inductively coupled plasma mass spectrometry -- CV coefficient of variation -- CI confidence interval -- D precision range -- TSH thyroid-stimulating hormone -- FT3 free triiodothyronine -- FT4 free thyroxine -- Tg thyroglobulin -- BMI body mass index; Critically ill -- Nutrition -- Periodicals; Diet therapy -- Periodicals; Parenteral feeding -- Periodicals; Enteral feeding -- Periodicals; Enteral Nutrition -- Periodicals; Parenteral Nutrition -- Periodicals; Metabolism -- Periodicals; Diétothérapie -- Périodiques; Alimentation parentérale -- Périodiques; Alimentation entérale -- Périodiques; Nutrition -- Périodiques; Diet therapy; Enteral feeding; Nutrition; Parenteral feeding; Electronic journals; Periodicals; Electronic journals; 615.854
• DOI: 10.1016/j.clnu.2020.12.010
• Languages: English
• ISSNs: 0261-5614

Abstract

Summary: Background: Saliva iodine concentration (SIC) has been found to be a good indicator of iodine nutritional status. However, limited information is available regarding saliva iodine characteristics. Aims: The study aimed to evaluate intra-day, intra-individual, and population SIC variation in order to provide information on optimal sample size and sampling time for assessing iodine nutritional status. Methods: Twenty-nine healthy school-aged students were recruited. Iodine intake from diet and water, and iodine excretion through urine and feces were assessed over a three-day period. Saliva samples were collected six times a day. Results: Diurnal variations were observed in SIC corresponding to iodine intake. The mean CV in SIC was lower than that for 24-hour urinary iodine concentration (24-h UIC) and 24-hour urinary iodine excretion (24-h UIE) not only at the individual level (42.73% vs. 47.71% and 49.69%) but also at the population level (71.29% vs. 100.43% and 72.49%). The number of saliva samples needed to estimate the iodine level with 95% CI within precision ranges of ±10%, ±20% was 55, 14 in an individual, and 180, 45 in a population. There was a good correlation between post-lunch SIC and total daily iodine intake. Conclusions: Saliva iodine has utility for evaluating the recent iodine nutrition of individuals and populations. The variation in SIC was lower than that for 24-h UIC and 24-h UIE. Saliva may be preferred over urine because of its ease of collection. Fourteen samples are needed to assess individual iodine status and forty-five saliva samples for assessment of population iodine status with reasonable precision. We recommend that saliva samples be collected after 14:00 in a day.