Does a negative PTHrP result rule out malignancy?
Unfortunately, a normal (or negative) concentration of parathyroid hormone related protein (PTHrP) does not rule out the presence of malignancy. PTHrP is only one of a number of factors that tumors may secrete that can result in an elevated calcium concentration (e.g. interleukins, tumor necrosis factor, etc.). Thus even if the PTHrP concentration is within normal limits, malignancy may still be present. A positive PTHrP concentration is indicative of malignancy, since PTHrP is not normally secreted in an appreciable quantity in adult animals.
