HYPOTHYKOIDISM 383 



advanced medical knowledge in those countries where, this disease was 

 earliest recognized and studied. Certain it is, however, that typical spo- 

 radic cretinism and myxedema are less frequently found in America where 

 C. P. Howard, in 1905, collected but a hundred myxedema cases from 

 the literature. It is interesting that at least one hundred cases have been 

 reported in California by H. C. Moffitt, the writer, and others. Many of 

 these cases had migrated to this mild climate on account of their great 

 sensitiveness to the cold. 



The relation of the distribution of sporadic hypothyroidism to the 

 endemic cretinic degeneration is of interest. Myxedema is certainly no 

 more prevalent in such endemic areas than elsewhere. At times it is less 

 common. As sporadic cretins in such localities are usually confused with 

 the endemic disease, it is difficult to form conclusions in this respect. 



Etiology 



Heredity and Familial Occurrence. The marked hereditary tendency 

 of hypothyroidism, though long recognized, has scarcely been sufficiently 

 emphasized. On account of the sterility frequently accompanying severe 

 hypothyroidism, such cases are rarely met. Exceptions do occur, such 

 as Mcllwaine's case. More often the parents of cretins show signs of 

 thyroid disease, goiter, thyrotoxicosis, dysthyroidism or mild myxedema. 

 In thyroaplasia characterized by congenital absence of the thyroid gland, 

 heredity is to be regarded as the exciting cause of the disease. Both 

 typical cretinism and myxedema have been reported among children of 

 the same family, particularly sisters. C. Herrman (b) described three spo- 

 radic cretins and A. G. Paterson two myxedemic patients of the same 

 parents. In the writer's series is an interesting thyroid family showing 

 hereditary obesity, two sisters being myxedemic, a third weighing 225 

 pounds at 50 years, then developing exophthalmic goiter. Other members 

 suffered from mental diseases, Barrett's remarkable family had sixty-two 

 members with anomalies ascribable to hypothyroidism. It is probable 

 that, with the recognition of increased numbers of light hypothyroid cases 

 with recent new diagnostic aids such as the basal metabolism, the familial 

 tendency will be more often demonstrated. Heredity probably plays an 

 important predisposing as well as exciting etiological role. A study of 

 many cases of hypothyroidism makes it probable that the thyroid tissue 

 of various members of a family may be hereditarily deficient, yet enough 

 being present for all ordinary requirements. However, when undue strain 

 such as many pregnancies, infections, toxemias, etc., occur, sclerotic and 

 atrophic processes ensue in such glands with abnormal rapidity followed 

 by the development of hypothyroidism. Other endocrin glands may be 

 hereditarily deficient in similar fashion. 



