Evaluation and Follow-up of Clinically Euthyroid Children with Normal Free T4 and Suppressed TSH

Aim Although subnormal TSH between 0 10 4 mIU/L is fairly common and benign, suppression of TSH to < 0 1mIU/L with normal free T4 is less common and more worrisome We have conducted a retrospective chart review of a collection of such cases and have summarized the features and outcome on follow up Methods We studied 23 consecutive patients referred from 2005-07 to our pediatric endocrine clinic with TSH < 0 1 mIU/L and free T4 in the range of 0 8-2 ng/dl We collected historical, clinical and laboratory data, and analyzed their outcome Results The natural evolutions of these subjects were separated into 4 groups Group 1, 14 subjects, (61%) became euthyroid within a mean of 3 7 months Group 2, 4 subjects, (17%) became hypothyroid within a mean of 2 8 months Group 3, 2 subjects (9%) progressed to overt hyperthyroidism Group 4, 3 subjects (13%) had persistently suppressed TSH, 8-14 months after initial testing, of which one had a multinodular goiter and had a thyroidectomy Elevated thyroid peroxidase antibody (TPO) was seen in 54 5% of those tested Conclusion Only 2/23 in our series became overtly hyperthyroid Substantial number of subjects had a short period of transient TSH suppression that resolved spontaneously Markers suggestive of autoimmune thyroid disease were consistently seen in group 2 and less so in others It is prudent to observe such cases in the short term with serial follow up TSH, free T4 and T3, and to reserve further testing and treatment for those who become symptomatic or do not resolve