We recently heard from a man who went to Germany and had Lu177 treatment. Simultaneously, he had also been taking Zytiga with prednisone and Xgeva. He has been experiencing severe calcium loss. Why might this be happening, and what should he do?
Xgeva is a bone health drug (like Zometa). It is FDA approved for men who are castrate resistant to help offset the loss of bone mineral density caused by hormone therapy (ADT). Its job is to build and maintain bone mineral density. Its mode of action involves using serum calcium in the blood to maintain bone mineral density.
PSMA-617 (the ligand used with Lu-177), is a chelating agent like the gadolinium contrast agent used with MRIs. PMA-617 can bind to the serum calcium so that it cannot be utilized by the bones to maintain their density, even in the presence of Xgeva. This can well explain why this man has been experiencing a severe loss of calcium in his blood, which could be the reason he has also experienced a loss of bone mineral density.
If you experience drops in your serum calcium while on bisphosphonates or Xgeva this might be a strong indicator for you to ask your doctor about adding calcium and vitamin D to maintain the calcium levels. In addition ask your doctor to check your blood pH, parathyroid, Vitamin D, calcitonin, magnesium, phosphate, citrate, creatinine, and albumin levels.
In the situation where calcium drops are severe, and everything else checks out, or if it doesn’t respond to supplementation, calcium infusions may be indicated. Again, discussing this issue with your doctor is vital.
Calcium is not only crucial for bone health in men with advanced prostate cancer; it plays an essential role in nerve conductivity and muscle contraction.
