Hyperphosphatemia in multiple myeloma due to a phosphate-binding immunoglobulin
Article Abstract:
Laboratory tests are generally quite reliable, but sometimes the results may be influenced by other factors. Hyperphosphatemia, an excess of phosphate in the blood, may be caused by kidney failure or by several conditions that involve tissue destruction, such as those that occur in some cancers. Patients with multiple myeloma may have spurious findings of hyperphosphatemia on the standard laboratory test. The increased measurements of phosphate appear to be the result of the presence of large amounts of antibodies that bind phosphate. Myelomas are malignancies of antibody-producing cells; the antibodies produced in large amounts by myelomas are often called paraproteins. It is sometimes considered that a finding of hyperphosphatemia in such a patient is of no consequence to the patient's health. However, in the recent case of an 86-year-old woman, laboratory tests revealed hyperphosphatemia and a phosphate-binding paraprotein. However, further testing revealed clinically significant hyperphosphatemia, which may lead to osteomalacia, a softening of the bones. In the present case, the patient was admitted for a broken hip; laboratory testing revealed a paraprotein indicative of myeloma. The diagnosis of multiple myeloma was confirmed by examination of a bone marrow specimen. Laboratory testing also revealed hyperphosphatemia. However, the significance of the finding was suspect because the paraprotein was found to bind phosphate. The clinical significance of the laboratory finding of hyperphosphatemia was evaluated by the measurement 1,25-dihydroxyvitamin D. The synthesis of 1,25-dihydroxyvitamin D is suppressed by phosphate in the blood, and a decrease in this substance, as was observed in the present patient, is indicative of clinically significant hyperphosphatemia. In the absence of kidney disease, hyperphosphatemia should alert the physician to a abnormality in immunoglobulin in the blood. However, if such an abnormality is found, it should not be assumed that the hyperphosphatemia is of no clinical importance. Measurements of 1,25-dihydroxyvitamin D might be useful in distinguishing physiologically significant hyperphosphatemia. (Consumer Summary produced by Reliance Medical Information, Inc.)
Publication Name: Cancer
Subject: Health
ISSN: 0008-543X
Year: 1991
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Prognostic factors in multiple myeloma
Article Abstract:
Multiple myeloma is a cancer of antibody-producing cells. Unfortunately, this cancer is on the rise, and both the incidence (number of new cases) and mortality of multiple myeloma are increasing. There have been few improvements in the treatment of this disease in the last 10 years. A total of 276 cases of multiple myeloma were analyzed to determine which factors have the greatest influence on survival. It was found that the greatest single factor is the degree of plasmacytosis. Plasmacytes are blood cells, and the appearance of more than 30 percent of these cells in the bone marrow indicates poor prognosis. Excessive calcium in the blood and reduced amounts of the blood protein albumin are also associated with poorer survival. Less important, though still significantly associated with poor survival, are decreased amounts of the enzyme alkaline phosphatase in the blood, increase amounts of uric acid, and insufficient kidney function. The overall survival of the patients was 49 percent at two years, that is, 49 percent of the patients with multiple myeloma were alive two years after diagnosis. Women were found to survive longer than men; the midpoint survival period was 29 months for the women and 19 months for the men. (Consumer Summary produced by Reliance Medical Information, Inc.)
Publication Name: Cancer
Subject: Health
ISSN: 0008-543X
Year: 1991
User Contributions:
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