Hi there. I am 56, diagnosed with osteoporosis in 2019 to the tune of -3.5. Initially I ruled out parathyroid disease.....sent my labs to Norman Clinic etc. They said they thought it was unlikely. My question is: Does a DXA showing that my forearm is worse than my spine or femeral neck indicate that there could still be a parathyroid issue? During the course of getting a bunch of labs, I did ask for a right arm dxa.....and it was indeed, worse than the other locations. I have been treating with Tymlos for two years.....with not much improvement so thinking of trying a new med (Evenity) but still have this question in the back of my mind if the osteoporosis could be the result of a parathyroid issue. My calcium before Tymlos was 9.7 mg/dl and PTH ranges from 24 to 50 pg/ml. Any insight? Thanks!
Parathyroid disease does cause osteoporosis, and typically the worst bone loss is seen in the forearm. Whenever someone has more significant bone loss in the forearm than the hip or spine, it is reasonable to think about primary hyperparathyroidism as the cause.
The way we diagnose primary hyperparathyroidism is with labs, primarily calcium and PTH levels. Since your calcium and PTH levels have been normal, the likelihood of having primary hyperparathyroidism is very low. Even though the DEXA scan results raise a concern for parathyroid disease, the labs rule it out. Some people will just have a similar pattern of bone loss (worse in the forearm than other locations) but it is unrelated to parathyroid disease.
Of note, if you did have primary hyperparathyroidism, you would not want to take Tymlos, which is essentially an injection of a piece of parathyroid hormone (PTH). Prior to prescribing Tymlos (or Forteo, a similar drug) doctors will check calcium and PTH levels to make sure you do not have primary hyperparathyroidism. The drug will not help if you already have too much PTH.