Heart rate Variability and Efficiency Assessment of Graves' Disease Radioiodine Therapy

Abstract

Time of the transformation to the euthyroid condition after radioiodine therapy of Grave’s disease is individual and deviates from weeks to months, what requires frequent hormones control. The aim of this study was the assessment of possibility to use HRV parameters in dynamic control after the radioiodine therapy. 77 patients were examined with 114 fT4 measurement and HRV parameters recording (before radioiodine administration and in 1, 3, 6, 12 months after). From HRV parameters two were chosen as characterizing the closest correlation with fT4 and relatively independent from each other. The whole sample was divided into the teaching set (86 measurements) and the test set (28 measurements). The decision rule was found by support vector machine in the teaching set asf(HR,SDNN) = 0.995 lg(HR) – 0.104 lg(SDNN) – 1.703, where f is the indicator of the thyroid gland function, HR – heart rate during 5-minute ECG recording; SDNN – standard deviation of RR intervals; 0.995 , 0.104 and 1.703 – correcting coefficients. If f > 0, the thyrotoxicosis takes place in a patient. If f < 0 – there is no thyrotoxicosis. The analysis of diagnostic method precision in testing set gave the following results: diagnostic sensitivity was 71%, the diagnostic specificity 79%. This method can predict thyrotoxicosis elimination or relapse with high possibility. Its use can optimize thyroid function control and refuse from fixed time hormone measurement.