Abstract
Studies made in this laboratory of the Ca metabolism in certain ductless gland disturbances have emphasized to us the unsatisfactory nature of the views held with regard to Ca distribution and calcification. In our case of acromegaly 1 with hyper-function of hypophysis Ca absorption and excretion were marked, the absorption apparently taking place even from the difficulty soluble residue in the lower intestine. After parathyroidectomy 2 absorption and excretion were very low. The Ca content of the blood however increased slightly which has been shown for P also by Greenwald. 3 There is decreased P catabolism but increase in the blood and Ca deprivation of tissues due to impaired excretion. Hyperthyroidism with its nervous symptoms would represent increased catabolism with more normal excretion. The apparent opposition of thyroid and parathyroid is likewise explained by greater catabolism in presence of thyroid than in absence of both.
These facts and a host of others related to endocrinous gland function may be interpreted briefly as follows. The intestinal epithelium and leucocytes invading it (probably the splanchnic basophiles) by virtue of the phosphonuclease they contain liberate from nucleic acid (possibly other phosphoric esters also) phosphoric acid which dissolves Ca phosphate. Ca is carried partly in combination with the leucocytes and is necessary for nucleolytic action. Macallum 4 has shown these cells to absorb and transport iron salts. Westbrook found the cells in extremely large numbers in villi of carnivora, particularly the dog (bone ingestion?). 5 In decalcification of bone the osteoclasts act in a similar manner. In ossification the osteoblasts split off acid Ca phosphate which hydrolyzes to the carbono-phosphate.
The question as to why only certain tissues as cartilage calcify is a distinct problem but may be largely a matter of chemotaxis.
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