A study of iodine nutritional status and the difference of urinary iodine before and after creatinine correction in patients with thyroid disease

ZHANG Liu; LIU Bowei; MA Ning

doi:10.3969/j.issn.1002-7386.2025.05.014

Abstract：Objective To investigate the iodine nutritional status of patients with thyroid disorders in iodine-sufficient area and the difference of urinary iodine level before and after creatinine correction.Methods A total of 1351 patients with thyroid disorders visited our hospital from January to December 2023 were enrolled as the case group,including 71 pregnant patients.The random urine creatinine was tested along with urine iodine in 213 patients and the urine iodine creatinine ratio(UI/Cr)was calculated.By disease type,the group was divided into hyperthyroidism group(252 cases),hypothyroidism group+Hashimoto's thyroiditis group(669 cases),thyroid nodule group(399 cases),and postoperative thyroid group(31 cases).There were 210 subjects with non-thyroidal disorders who visited the clinic during the same period were enrolled as the control group.Gender,age,thyroid-stimulating hormone(TSH),free triiodothyronine(FT3),free thyroxine(FT4),thyroglobulin antibody(TgAb),thyroid peroxidase antibody(TPO-Ab)and urinary iodine were counted for all subjects.Results The median urinary iodine(MUI)in the case group was significantly lower than that in the control group(141.80[85.50,223.70]μg/L vs 161.60[102.63,243.90]μg/L,Z=-2.345,P＜0.05),while the difference was not statistically significant in MUI between the case groups(Z=0.441,P＞0.05).The difference was statistically significant in the proportion of iodine deficiency between the case group and control group(32.6％ vs 25.2％,Z=-2.657,P＜0.05),but there were no statistically significant difference in the proportion of iodine appropriateness(37.8％ vs 42.4％,Z=-0.715,P＞0.05)and proportion of above adequate+iodine excess(29.5％ vs 32.4％,Z=-0.109,P＞0.05)between the case group and control group.The MUI of 71 pregnant patients was 153.00(90.40,224.20)μg/L,iodine deficiency accounted for 49.3％,iodine moderation accounted for 31.0％,and greater than the appropriate amount+iodine excess accounted for 19.7％.Urinary creatinine was tested simultaneously in 213 cases,the difference was statistically significant in MUI of creatinine patients between before and after correction(136.10[84.10,206.10]μg/L vs 100.45[65.70,150.49]μg/g,Z=-5.435,P＜0.001).The differences were statistically significant in the proportions of iodine deficiency(34.7％ vs 51.6％,Z=-4.401,P＜0.001),adequate iodine(39.4％ vs 33.3％,Z=-5.453,P＜0.001)and above adequate+iodine excess(25.8％ vs 15.0％,Z=-2.983,P＜0.01).Conclusion In the Qinhuangdao area,the iodine nutritional status of patients with thyroid disease distributes in similar proportions among the deficient,appropriate,and excess populationsl,and the pregnant patients with iodine deficiency is nearly half,which should be more concerned.After comparing the subjects'own urinary iodine level before and after correction,it is found that the urinary iodine level corrected by creatinine is significantly lower,and this indicator as the assessment of iodine nutritional status more prominent proportion of iodine-deficient people.