556 UNCLASSIFIED MENTAL RETARDATION

SIR,-How interesting

to

watch other

people’s reactions

to

their

being mentioned in editorials. Dr Ounsted and Dr Redman (Feb. 17, p. 387) say that your editorial of Feb. 3 (p. 250) was mainly concerned with a joint paper of theirs, when only 20% (v/v) of it was. I had thought until their letter that the editorial was mainly concerned with my own work, since nearly 80% certainly was. However, Ounsted and Redman are surely mistaken in saying that you suggested an association between head size and mental development among the infants in her study. You specifically stated that "postnatal catch-up of head growth occurred"; "... nor was any neurological impairment detected"; and you expressed the opinion that "a serious [intellectual] deficit" was "unlikely in the long term" in the cases reported by Ounsted, Redman, and their colleagues. This, of course, would have been the expected finding if, as you also remarked, the difference in head circumference in these children had been small. Department of Child Health, University of Manchester, Medical School, Manchester M13 9PT

JOHN DOBBING

THYROTROPIN-RELEASING-HORMONE TESTS

SIR,-Dr Staub and colleagues (Jan. 27,

p. 209) report that thyrotropin (T.S.H.) response to intravenous thyrotropinreleasing hormone (T.R.H.) is impaired in conditions other than hyperthyroidism. We have given T.R.H. by mouth for 3 days and measured serum T.s.H. and T3 in five groups of patients. On the basis of serum T3 and T4 (normal >2.0 U/ml), T.S.H. response to 200 T.R.H. and a scan the patients were classified i.v., thyroid ug as normal controls (n=5), non-toxic goitre with normal T.S.H. response (n=6), non-toxic diffuse goitre with impaired T.S.H. response (n=5), euthyroid with a single hot nodule and impaired T.S.H. response (n=8), or mild hyperthyroidism (n=6).

the

The patients took T.R.H. 20 mg at 8 A.M., noon, 4 P.M., and 8 P.M. for 3 days, and venous blood was drawn every 30 min for the first 4 h for estimation of serum T.s.H., and at 0, 4, 6, 8, 14, 24, 28, 32, 48, 52, and 56 h for estimation of serum-T3’ Significant increases in serum-T.S.H. were found in all groups, including the hyperthyroid one. Compared with the group with diffuse non-toxic goitre and impaired T.S.H. response, the two groups with normal i.v. T.R.H. stimulation test showed a significantly greater T.s.H. response to oral T.R.H. (P

Thyrotropin-releasing-hormone tests.

556 UNCLASSIFIED MENTAL RETARDATION SIR,-How interesting to watch other people’s reactions to their being mentioned in editorials. Dr Ounsted a...
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