HYPOTHYROIDISM 395 



both experimentally and chemically to lead to increased alimentary toler- 

 ance for glucose ( Knopf elmacher, McCurdy, Van Noorden (d)). The 

 contradictory results obtained by R. Hirsch are subject to other explana- 

 tion. Gordon noted a tendency of the sugar tolerance of myxedemics to 

 return to normal on thyroid medication. Recently, hypoglycemia has been 

 reported in cretinism, myxedema and in thyroidectomized animals (Geye- 

 lin, Janney & Isaacson (&) ). Experimentally we were able to demonstrate 

 a distinct hypoglycemia and a delayed return of the blood sugar level to 

 normal on feeding glucose to thyroidless dogs. Rarely glycosuria has 

 been reported in hypothyroidism (Van Noorden (a-)). 



The Fat Metabolism. Like many other endocrin dystrophies, hypo- 

 thyroidism is accompanied by a tendency to obesity of endogenous nature. 

 This manifestation of disturbed metabolism comes on early and is per- 

 sistent. Inasmuch as loss of fat which occurs on proper thyroid medication 

 is accompanied by a return of the sugar tolerance to normal limits, thyroid 

 adiposity would seem related to the aberrant carbohydrate metabolism 

 in some manner as yet not fully understood 



Statements in the literature in explanation of the metabolic phenomena 

 observed in hypothyroidism are vague and meager. Magnus-Levy's (/) at- 

 tempts to account for the lowered gaseous exchange of hypothyroidism by 

 delayed alimentary absorption of food have, as is noted above, been proven 

 erroneous. The lower nitrogen excretion has been accounted for as due 

 to "lack of the stimulatory effect of the thyroid on metabolism." The 

 writer (&)' has previously called attention to the inadequacy of such an ex- 

 planation and endeavored to supply the rationale of hypothyrqidism, which 

 may be summarized as follows : "It is now possible to formulate a more 

 definite conception of the metabolism of hypothyroidism if we keep closely 

 in mind that the thyroid gland functions normally to maintain cellular 

 nutrition and growth. In hypothyroidism these processes are inhibited; 

 the gaseous exchange becomes subnormal and the excretion of protein 

 metabolites is diminished. Experiments carried out by the writer and 

 co-workers demonstrated that even greatly increased amounts of food 

 failed to alter this condition, although the food was well absorbed. Nitro- 

 gen balance observations on cretins showed that a normal amount of nitro- 

 gen could not be retained by the body tissues and therefore was elimi- 

 nated by the kidneys in relatively increased amounts. The cretin, how- 

 ever, routinely ingests less food than normal, very probably because it can- 

 not be properly assimilated. Therefore the decreased appetite and low- 

 ered nitrogen excretion which is commonly observed in this condition. The 

 basal metabolism is probably set at a lower level in order to spare the tissues 

 as much as possible from ordinary fuel and waste processes as the cells 

 cannot be synthetically repaired and replaced by nutritional processes re- 

 quiring a normal supply of the thyroid hormone. Many examples of 

 such a sparing effect are known in metabolism. The abnormal excretion 



