Parathyroid Hormone related Protein (PTHrP) plays an important role in the body including intracellular regulation of calcium levels in brain cells, activating sensory and motor neurons and modulation of pain. Calcium is involved in the regulation of neurotransmitter release from the neurons, the process of aging, gene expression, muscle contraction and in signal transduction between cells in the body. Balance of calcium in cells and in the body depends on the action of the parathyroid hormone (PTH) and PTHrP.
In humans, PTHrP is produced in various tissues, including kidneys, bones, placenta, skin, brain and central nervous system. However, there is a controversy regarding the presence of the PTHrP in the CNS and its role in brain physiology and pathology.
Investigators at the ARUP Institute for Clinical and Experimental Pathology in Salt Lake City, Drs. Mark Kushnir, Lisa Peterson and Frederick Strathmann (F. Strathmann is currently employed at NMS Labs in Willow Grove, PA) conducted research with the aim of determining whether PTHrP is present in CSF, and if it correlates with PTHrP concentrations in serum. PTHrP and calcium were measured using mass spectrometry based methods in a collection of 140 paired human serum and CSF samples obtained from individuals without neurologic diseases. The results of the study are now published in the journal Clinical Biochemistry.
In this study, the authors determined that PTHrP is a normal constituent of human CSF with median CSF-PTHrP concentrations 51 fold higher than in serum; whereas, the observed median concentrations of Ca in CSF was 1.8 times lower than in serum. Concentrations of PTHrP in CSF and serum were positively correlated, suggesting that CSF could be a significant source of PTHrP in circulating blood. It was also observed that serum PTHrP concentrations were positively correlated with age and were significantly higher in women. In addition, the authors observed association between albumin indices and PTHrP-serum/PTHrP-CSF ratios.
Taken together, the results of the study indicate that PTHrP is a normal constituent of human CSF, that CSF PTHrP concentrations are much higher than in the serum and that CSF derived PTHrP may contribute to disorders of Ca regulation.
Mark M. Kushnir, Lisa K. Peterson, Frederick G. Strathmann Parathyroid hormone related protein concentration in the human serum and CSF correlates with age Clinical Biochemistry 52 (2018) page 56–60