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Background Diagnostic re-evaluation is important for all patients with congenital hypothyroidism (CH) for determining the etiology and identifying transient CH cases. Our study is a first thyroxine therapy withdrawal study conducted in Macedonian CH patients for a diagnostic re-evaluation. We aimed to evaluate the etiology of CH, the prevalence of transient CH and identify predictive factors for distinguishing between permanent (PCH) and transient CH (TCH). Materials and methods Patients with CH aged >3 years underwent a trial of treatment withdrawal for 4 weeks period. Thyroid function testing (TFT), ultrasound and Technetium-99m pertechnetate thyroid scan were performed thereafter. TCH was defined when TFT remained within normal limits for at least 6-month follow-up. PCH was diagnosed when TFT was abnormal and classified according the imaging findings. Results 42 (55%) patients had PCH and 34 (45.0%) patients had TCH. Thyroid agenesia was the most prevalent form in the PCH group. Patients with TCH had lower initial thyroid-stimulating hormone (TSH) values (P P = 0.0023) and lower mean doses of levothyroxine during treatment period (P Conclusion TCH presents a significant portion of patients with CH. Initial TSH value and levothyroxine dose during treatment period has a predictive role in differentiating TCH from PCH. Earlier re-evaluation, between 2 and 3 years age might be considered in some patients requiring low doses of levothyroxine.

To evaluate the thyroid screening program and to estimate the prevalence of congenital hypothyroidism (CH) among newborns in the Republic of Macedonia, we measured thyroid-stimulating hormone (TSH) levels in dried blood spot specimens using the DELFIA fluoroimmunoassay, over a period of 12 years. The TSH cutoff level was 10 mU/L blood. A total of 215,077 newborns were screened (94.76 %). Out of 254 recalled newborns (a recall rate of 0.15 %), 83 newborns with CH were detected, yielding a CH prevalence at screening of 1/2,591 (female to male ratio, 1.86:1). Of the CH cases, 47/107,754 (56.6 %) neonates were Macedonian, 29/70,330 (34.9 %) were Albanian, and 7/15,055 (8.4 %) were Roma. The thyroid gland was undetectable on ultrasound in 43 (51.8 %) newborns with CH, thyroid hypoplasia was confirmed in 8 (9.6 %), while 29 (34.9 %) had a normal thyroid gland. In three newborns (3.6 %), agenesis of one lobe was confirmed. Therapy with levothyroxin was initiated on average 11.7 days after birth. Conclusion: The national thyroid newborn screening program in Macedonia has been successful and effective, providing timely diagnosis and treatment of children with congenital hypothyroidism.