CHAPTER XXVII 



EFFECT ON THE THYROID AND PARATHYROID GLANDS 



The variably atrophic changes in the thyroid gland during inanition doubt- 

 less account for the typical decrease in basal metabolism during various condi- 

 tions of malnutrition. Iodin deficiency, however, results in simple goiter, a 

 fact of great importance in preventive medicine. The parathyroid glands 

 similarly tend to hypertrophy during rickets, although they undergo slight 

 atrophy in other types of inanition. After a brief summary, the details will be 

 reviewed separately for the thyroid and the parathyroid glands. 



Summary of Effects on the Thyroid and Parathyroid Glands 



Thyroid Gland. — During total inanition (or on water only) in adult man or 

 animals, there is typically a definite atrophy of the thyroid, but the loss in 

 weight is somewhat variable, usually relatively less than that of the whole 

 body. In the young, the changes in thyroid weight are still more variable. 

 In atrophic infants, there is a profound thyroid atrophy in most cases. In 

 malnourished young animals, the weight is variable; sometimes there is little 

 or no loss, or even a slight gain, but never the persistent growth found in many 

 other organs. During partial inanition in adults, a variable loss in thyroid 

 weight is characteristic (in deficiencies of protein, vitamins and water) ; although 

 there may be irregular enlargement in scurvy, and a very marked hypertrophy 

 in iodin deficiency, the apparent cause of simple goiter in man and animals. 



In structure, the thyroid changes during inanition are variable, but typically 

 there is more or less hyperemia, with atrophy of the parenchyma and increase 

 of stroma (sclerosis). In the follicles, the epithelial cells may show simple 

 atrophy, or progressive stages of degeneration, with cytoplasmic vacuolation, 

 loss of granulation, etc., and typical nuclear degenerative changes. There may 

 be desquamation of degenerated cells, and in extreme cases a total disintegra- 

 tion of follicles. The fat granules in the thyroid cells appear uninfluenced by 

 inanition. The colloid is extremely variable, in some cases reduced in amount, 

 in others increased so as to distend the follicles. 



During hibernation, the thyroid apparently undergoes atrophic changes 

 correlated with a condition of functional depression. 



During partial inanition, the thyroid changes in structure are in general 

 similar to those during total inanition. The congestion and markedly degen- 

 erative changes are frequently (perhaps always) due to infections, which often 

 complicate the late stages of inanition. Hemorrhages sometimes occur, espe- 

 cially in scurvy. In the thyroid hypertrophy due to iodin deficiency, the changes 

 are variable according to species and stage of inanition. Apparently a follic- 

 ular hyperplasia with shortage of colloid is usually characteristic of the earlier 



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