RESUMEN
Purpose: Secondary acquired lacrimal duct obstruction (SALDO) is one of the complications of radioiodine therapy. SALDO is formed a few months after therapy if there is a sufficient uptake of radioactive iodine by the nasolacrimal duct. To date, risk factors leading to SALDO are unclear. The objective was to determine the correlation between the tear production level and radioactive iodine-131 uptake in the lacrimal ducts. Methods: Basal and reflex tear production was studied in 64 eyes prior to the therapy with radioactive iodine-131 after drug-induced hypothyroidism. The condition of the ocular surface was assessed using the Ocular Surface Disease Index (OSDI) questionnaire. Seventy-two hours after the radioactive iodine therapy, scintigraphy was performed, which determined the presence or absence of iodine-131 in the lacrimal ducts. T-statistics and the Mann-Whitney criterion were used to identify the differences between the groups. The differences were considered significant at P ≤ 0.05. The current tear production level in patients receiving radioiodine therapy was determined using a mathematical model. Results: A statistically significant difference between the basal (p = 0.044) and reflex (p = 0.015) tear production levels was found in cases with and without iodine-131 uptake by the lacrimal ducts. The probable current tear production level corresponds to the sum of basal and 10-20% of reflex tear production. The uptake of iodine-131 was found regardless of the OSDI results. Conclusion: The probability of iodine-131 uptake by the lacrimal ducts rises as the tear production level increases.
Asunto(s)
Aparato Lagrimal , Obstrucción del Conducto Lagrimal , Conducto Nasolagrimal , Neoplasias de la Tiroides , Humanos , Aparato Lagrimal/diagnóstico por imagen , Radioisótopos de Yodo/efectos adversos , Conducto Nasolagrimal/diagnóstico por imagen , Obstrucción del Conducto Lagrimal/diagnóstico , Obstrucción del Conducto Lagrimal/etiologíaRESUMEN
RATIONALE: Insufficient world-wide clinical experience in radioiodine therapy (RIT) for Graves' disease (GD) in children and adolescents, and limited knowledge of the predictors of RIT efficacy. AIMS: Analysis and identification of the most significant predictors of the efficacy of RIT in children and adolescents with Graves' disease. MATERIALS AND METHODS: A total of 55 patients (48 females and 7 males) aged from 8 to 18 years receiving primary RIT for GD were enrolled. RIT planning was based on the dosimetric method. Analyzed parameters included gender, age, ultrasound thyroid volume before and 6 months after treatment, the presence of endocrine ophthalmopathy, duration of antithyroid drug (ATD) therapy, relapse of thyrotoxicosis after ATD dose reduction, blood fT3, fT4 and TSH levels initially and at 1, 3, 6 months after treatment, TSH receptor Ab initially and at 3 and 6 months after treatment, thyroid 99mTc-pertechnetate uptake at 10-20 minutes (%), maximum thyroid 131I uptake (%), specific 131I uptake (MBq/g) and therapeutic 131I activity (MBq). Fisher exact test, non-parametric Mann-Whitney test, Wilcoxon signed-rank test, logistic regression modelling, ROC-analysis, proportional hazard model (the Cox regression), the Kaplan-Meier method and log-rank test were used for statistical analysis as appropriate. RESULTS: Six months after RIT, hypothyroidism was achieved in 45 (81.8%), euthyroid state - in 2 (3.6%), and in 8 (14.6%) patients thyrotoxicosis persisted. On univariate statistical analysis, the smaller thyroid volume, higher fT4 and lower TSH receptor Ab levels, lower 99mTc-pertechnetate uptake and higher specific 131I uptake were associated with hypothyroidism. On multivariate logistic regression analysis, the older patient's age (p=0.011), smaller thyroid volume (p=0.003) and higher fT4 (p=0.024) were independent predictors of RIT efficacy. Thyroid volume was also the only variable associated with achievement of hypothyroidism in time after RIT (p=0.011). CONCLUSION: The efficacy of dosimetry-based RIT in children and adolescents with GD 6 months after treatment was 81.2%. Older patients' age, smaller thyroid volume and higher fT4 level were independent predictors of therapy success. Smaller thyroid volume was also a predictor of the favorable time-related outcome. Statistical models obtained in this work may be used to prospectively estimate the chance of efficient RIT for GD in pediatric patients.