Hypothyroidism and sex chromosomes.

The observation of Campbell and Price in 1979 that their Unit had diagnosed four subjects with both Klinefelter's syndrome and congenital hypothyroidism raised the suspicion of an association between the two conditions. This, and the published reports of an XX male, five XXY males, and one mosaic XY/XXY with congenital or acquired forms of hypothyroidism, together with the higher incidence in women and the absence of sex difference among inherited congenital cases, suggested a possible sex chromosome effect in the aetiology of sporadic hypothyroidism. Various hypotheses can be tested either by examining the frequency of hypothyroidism in sex chromatin positive males or by establishing a higher frequency of sex chromatin positive males among hypothyroid cases than in normal males. We examined 57 boys with hypothyroidism for the presence of sex chromatin and found all to be negative. From this relatively small sample we can only exclude the possibility of a very large (100 fold) difference in frequency between the two populations and therefore more data are needed.