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Anemia in infants with congenital hypothyroidism diagnosed by neonatal screening
A Franzese1, M Salerno, A Argenziano
1Dipartimento di Pediatria, Università di Napoli, Italy.
Insights
Anemia is common in infants with congenital hypothyroidism, especially with lower T4 levels at diagnosis. These hematologic changes may persist despite thyroid hormone replacement therapy.
Area of Science:
- Pediatrics
- Endocrinology
- Hematology
Background:
- Anemia is a known complication in adult hypothyroid patients.
- Limited research exists on anemia in infants with congenital hypothyroidism.
- Neonatal screening programs identify congenital hypothyroidism early.
Purpose of the Study:
- To investigate the hematologic status in infants with congenital hypothyroidism during their first year of life.
- To determine the relationship between the severity of neonatal hypothyroidism and hematologic parameters.
- To assess the impact of L-thyroxine treatment on anemia in these infants.
Main Methods:
- Retrospective review of 50 infants diagnosed with congenital hypothyroidism via neonatal screening.
- Hematologic assessments (Hb, Ht, RCC, MCV, MCH, serum iron, ferritin) performed at diagnosis, 3, 6, and 12 months.
- Patients categorized into two groups based on serum T4 concentration at diagnosis (<3 µg/dL vs. ≥3 µg/dL).
Main Results:
- Infants with lower T4 levels at diagnosis (Group A) showed significantly lower Hb, Ht, and RCC values at 3 months compared to Group B.
- Hb, Ht, and RCC values improved in both groups between 6 and 12 months.
- Mean MCV and MCH values were normal at diagnosis, decreased at 3 and 6 months, and normalized by 12 months, with no intergroup differences.
- Mean Hb levels at 3 months correlated with mean serum T4 at diagnosis.
Conclusions:
- Anemia is a frequent finding in infants with congenital hypothyroidism.
- The severity of anemia is dependent on the degree of neonatal hypothyroidism.
- Hypothyroidism during development may lead to lasting hematologic changes even after treatment initiation.
Abstract:
Although anemia is a common finding in adult hypothyroid patients, there are no studies on anemia in hypothyroid infants. The aim of this study, therefore, was to review the hematologic status during the first year of life in 50 infants with congenital hypothyroidism detected through the regional neonatal screening program. The mean age at diagnosis was 23.7 +/- 6.5 days and treatment was initially begun with a mean L-thyroxine dose of 6.8 +/- 1.3 micrograms/kg/day. Clinical and haematological assessments were performed at diagnosis, 3, 6 and 12 months of age. The patients were divided in 2 groups based on whether T4 serum concentration at diagnosis was < 3 micrograms/dl (Group A) or > or = 3 micrograms/dl (Group B). Data for hemoglobin (Hb), hematocrit (Ht), red cells count (RCC), mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), serum iron and ferritin were expressed as Standard Deviation Score (SDS). Although at diagnosis the mean value of Hb-SDS, Ht-SDS and RCC-SDS were in the low-normal range in both groups, at 3 months of age the values in Group A (Hb -1.9 +/- 0.79; Ht -2.34 +/- 1.02; RCC -1.56 +/- 1.25) were significantly lower than in Group B (Hb -1.14 +/- 0.78, p < 0.005; Ht -1.59 +/- 0.94, p < 0.05; RCC -0.55 +/- 1.32, p < 0.02). A rise of the Hb, Ht and RCC values was observed in both groups from 6 to 12 months. The mean values of MCV-SDS and MCH-SDS were in the normal range at diagnosis in both groups, decrease progressively at 3 and 6 months and returned to normal at 12 months of age; no differences were found between the 2 groups at any time. Mean Hb levels at 3 months of age were correlated with mean serum T4 at diagnosis (r = 0.30, p < 0.05). The present results indicate that anemia is a frequent finding in infants with congenital hypothyroidism and is depended on the degree of neonatal hypothyroidism and imply that hypothyroidism during development may produce persisting changes even after thyroid replacement has begun.