Increased serum levels of a parathyroid hormone-like protein in malignancy-associated hypercalcemia

Article Abstract:

It has been hypothesized that a substance similar to parathyroid hormone causes malignancies that are complicated by hypercalcemia, an excess of calcium in the blood. This parathyroid hormone-like protein (PLP) has been thought to play a role in triggering an immunologic response in this disorder. PLP has been detected by bioassay tests in breast and kidney tumors that are associated with hypercalcemia. A radioimmunoassay of PLP was developed using blood serum from patients with malignancies or with hyperparathyroidism (an over-active parathyroid gland), as well as from normal subjects. PLP levels were measured and the immunological role of this protein was assessed. Serum immunoreactive (iPLP) levels were measured and compared with the incidence of hypercalcemia associated with malignant tumors. In the normal subjects, 68 percent had no detectable levels of iPLP in their blood. In the patients with hypercalcemia associated with hyperthyroidism, iPLP concentrations were normal in 15 of the 16 patients. However, in patients with malignancy-associated hypercalcemia, increased serum iPLP concentrations were found in 36 of 65 patients (55 percent). In patients with cancer but without hypercalcemia, only three of 23 had elevated serum levels. These observations indicate that PLP functions as a mediator of hypercalcemia. Also, iPLP measurements may be useful in reaching a differential diagnosis in cases of suspected hypercalcemia. (Consumer Summary produced by Reliance Medical Information, Inc.)

Reports, Tumors, Protein research

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Parathyroid hormone-related protein in adult T-cell leukemia-lymphoma

Article Abstract:

Adult T-cell leukemia-lymphoma is a disease associated with infection by the retrovirus HLTV-1 (human T-cell lymphotrophic virus type 1) which is often accompanied by disorders of calcium metabolism. The presence of a parathyroid hormone-related protein (PTHrP) was assessed in three patients with T-cell leukemia-lymphoma, two of whom developed hypercalcemia (abnormally high levels of calcium in the blood). The parathyroid hormone is secreted by the parathyroid glands and regulates calcium and phosphorus metabolism. Genetic elements, specifically, the messenger ribonucleic acid (mRNA), which is involved in the production of PTHrP, were detected in the tumor cells of all patients. In addition, factors that activate the production of cyclic adenine monophosphate, a substance involved in several cell reactions, were identified in the lung and abdominal fluids of the two patients with hypercalcemia. The results show that PTHrP is produced by tumor cells of patients with T-cell leukemia-lymphoma. This factor may contribute to the development of hypercalcemia in these patients. Other factors such as the number of tumor cells, access of protein into the circulation, and the presence of other substances may also be involved in the disease processes leading to hypercalcemia in leukemia-lymphoma. (Consumer Summary produced by Reliance Medical Information, Inc.)

Adult T-cell leukemia-lymphoma

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Menopause without symptoms: the endocrinology of menopause among rural Mayan Indians

Article Abstract:

The hormonal changes in menopausal Mayan women are similar to those of US women but the Mayan women report few, if any, symptoms. Fifty-two post-menopausal and 26 pre-menopausal Mayan women in Chichimila, Mexico, were interviewed about menopause and menopausal symptoms such as hot flashes. The women had brief physical exams and blood samples were taken for hormonal testing. Bone density was also measured as a test for osteoporosis. No women reported experiencing hot flashes during menopause. However, estrogen levels in the Mayan women who had already completed menopause were similar to the values for women in the US. There was no history of osteoporosis in the post-menopausal group although measurable bone density loss was observed. Older women were not shorter than younger women. Decreasing height can also be an indicator of osteoporosis. Because menopause in Mayan culture is associated with a non-negative change in status, it is hypothesized that the cultural context plays a role in the lack of symptoms reported by Mayan women.

Health aspects, Demographic aspects, Menopause, Mayas

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