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In Reply.—We thank Nose et al for their interest in our observations. The explanation for the disparity between our observations and those of Dr Nose and his colleagues on systolic time intervals in children with thyroid dysfunction requires further evaluation; however, their contention that our data were inadequately corrected for subject age does not seem to sufficiently explain the differences. Gutgesell et al1 showed systolic intervals to vary positively with pulse rate and inversely with subject age. However, the inclusion of both pulse rate and age in multiple regression analysis led to less than a 2% improvement in the correlation coefficients, compared with single variable correlation analysis. Furthermore, in our evaluation of the influence of thyroid hormone on systolic time intervals, paired t tests were used. Hence, subjects were compared with themselves, rather than population means. These intrapatient comparisons should be more sensitive to small changes in the
HAYFORD JT, SCHIEKEN RM, THOMPSON RG. Systolic Time Interval in Infants and Children With Primary Hypothyroidism-Reply. Am J Dis Child. 1981;135(4):385. doi:10.1001/archpedi.1981.02130280075034