Project Title: 16, Exposure to External and Internal Radiation In Vivo Measurement of Radionuclides in Man; Body Burden and Kinetic Factors, Computer Applications Technical Progress in FY 1973: BX-01-0)-(h) (Cont'd.) Seven months following initiation ~* vitamin D therapy, the value fell to 142.1% of the total body calcium. Jhe results are consistent with the reduction in bone accretion and resorption rates that have previously been noted in patients with hypoparathyroidism. Findings of negative calcium balance and osteoporosis have been reported for acromegalic patients. A greatly increased bone turnover rate was observed in this disorder, with both accretion and resorption rates elevated. not yet clear what mechanism is responsible for these changes. It is Somatotropin increased bone collagen and protein synthesis; it also acts on kidney and intestine. Hypersomatotropism is generally marked by an increased retention of phosphorus along with an increased urinary calcium excretion. This condition may provoke a response of hyperparathyroidism, which tends to camteract the effects of somatotropism. Some evidence exists to support the hypothesis of hyperparathyroidism super-ijmposed on hypersomatotropism. The calcium levels of the hypersomatotropic patients in this study were often greatly elevated. Two male patients, for example, had calcium levels as high as 1600 g, in comparison to the 1150 g characteristic of a normal adult male. In terms of their expected calcium values, the mean calcium of a group of 12 patients was 104.4%. Although there is evidence of hyperphosphatemia in acromegalic patients, the mean P/Ca ration for the patients in this study fell in the normal range (0.55). After radiation therapy was administered to 7 patients, a decrease in the mean calcium : to 91,6% of the expected value was noted. There are conflicting reports of bone involvement reported for diabetes, Insulin affects both bone collagen and total protein synthesis.. It was found that for female diabetic patients the total skeletal mass was slightly lower than the range for normals; 93,0% of the cotal body calcium. Although there were wide variations in the phosphorus level, ratio for the group was within the normal range. the mean P/Ca These studies show that the TBNAA technique provides useful data for research in that it quantitatively links endocrine function with two parameters of skeletal metabolism: total body calcium and total body phosphorus, The data obtained are useful in elucidating the mechanisms by which endocrines influence skeletal mass and in the evaluation of therapeutic programs. Wnce chronic alcoholism has been shown to result in a type of osteoporosis Ca-47 kinetic techniques and in vivo neutron activation techniques were employed to study the mechanism of this osteopenia. The results to . date indicate a loss of body calcium in only two of the six alcoholics studied, Total body potassium in these subjects appears normal, (See Continuation Sheet) pedi 18 RX-18