THE MENTAL PROGNOSIS IN HYPOTHYROIDISM OF INFANCY AND CHILDHOOD

A Review of 128 Cases

¹ Department of Pediatrics, Johns Hopkins University School of Medicine, and the Endocrine Clinic of Harriet Lane Home, Johns Hopkins Hospital

A study of 128 children with hypothyroidism is presented. The mental attainments are evaluated in relation to the severity and age of onset of symptoms, and in relation to the age when adequate therapy was instituted. A summary diagram is provided depicting the duration of hypothyroidism in relation to the mental attainments for adequately treated patients.

The best result in severe cretinism, insofar as mental achievement is concerned, is obtained by early adequate therapy. Ten of twenty-two patients in the complete absence of thyroid function treated adequately before 6 months of age, and 12 of 29 patients treated adequately before 12 months of age eventually attained an I.Q. greater than 90. In contrast, none of 50 patients who were inadequately treated, or were treated after 12 months of age, attained such an I.Q.

Mild cretinism, with partial thyroid dysfunction, appears to confer partial protection against mental impairment as 13 of 32 such patients attained an I.Q. of 90 or greater even though not treated early.

Hypothyroidism acquired after 2 years of age apparently exerts little or no serious, irreversible effect on mental development as 13 of 17 patients with acquired hypothyroidism achieved an I.Q. of 90 or greater.

Neurologic sequelae, characterized by spasticity, tremor, and hyperactive deeptendon reflexes, are found frequently in severe cretinism, but not in mild cretinism or acquired hypothyroidism. The severity of neurologic sequelae parallels mental retardation. Early therapy apparently prevents, in part, these sequelae as only 4 of 22 patients with severe cretinism treated adequately in the first 6 months of life had these findings but 22 of 57 patients treated after this age or inadequately treated in the first 6 months, were afflicted with neurologic sequelae.

Early, adequate therapy may fail to establish normal mentality in a certain percentage of patients; 12 of 22 patients treated adequately in the first 6 months of life did not attain an intelligence quotient of 90 or greater. These patients apparently incurred such severe damage to the brain in utero that normal cerebral function could never be established. This surmise is supported by data presented showing a correlation of the severity of retardation of osseous development at birth with the severity of mental impairment.

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