TRH testing in its infancy

Newborn screening results in children with central hypothyroidism

OBJECTIVE

To investigate newborn screening results in children with congenital hypopituitarism, including central hypothyroidism, and to determine whether there were differences between children who had abnormal results and children with normal newborn screening results.

STUDY DESIGN

Medical records of children with central hypothyroidism observed in our pediatric endocrinology clinics from 1990 to 2006 were reviewed.

RESULTS

Forty-two subjects (22 boys) were identified. Eight children (19%) had a low total thyroxine level (<5.0 mcg/dL) on the newborn screening test. The average total thyroxine level in the remaining 34 subjects was 9.8 +/- 3.4 mcg/dL. Thyrotropin levels were within the reference range in all children. No differences were found in the 2 groups for birth history, jaundice (53% overall), hypoglycemia (36% overall), or micropenis (43% of boys). Fifty-seven percent of children had septo-optic dysplasia, and 98% had multiple pituitary hormone deficiencies. Children with an abnormal newborn screening results were initially examined by a pediatric endocrinologist at an average age of 4.6 +/- 5.0 months, and children with normal newborn screening results were initially examined at an average age of 16.9 +/- 26.7 months (P = .037).

CONCLUSIONS

Most children with congenital central hypothyroidism have normal thyroid function at birth. Normal newborn screening results can be falsely reassuring and may contribute to a delay in diagnosis of hypopituitarism despite classic clinical features.