Diagnostic re-evaluation of congenital hypothyroidism in Macedonia: predictors for transient or permanent hypothyroidism
Journal
Endocrine Connections
Date Issued
2018
Author(s)
DOI
10.1530/EC-17-0332
Abstract
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 < 0.0001); higher serum thyroxine levels
(P = 0.0023) and lower mean doses of levothyroxine during treatment period (P < 0.0001)
than patients with PCH. Initial TSH level <30.5 IU/mL and levothyroxine dose at 3 years
of age <2.6 mg/kg/day were a significant predictive factors for TCH; sensitivity 92% and
100%, specificity 75.6% and 76%, respectively.
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.
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 < 0.0001); higher serum thyroxine levels
(P = 0.0023) and lower mean doses of levothyroxine during treatment period (P < 0.0001)
than patients with PCH. Initial TSH level <30.5 IU/mL and levothyroxine dose at 3 years
of age <2.6 mg/kg/day were a significant predictive factors for TCH; sensitivity 92% and
100%, specificity 75.6% and 76%, respectively.
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.
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