Autotransplantation of parathyroid tissue into a forearm may be done:
(1) following a total parathyroidectomy for hyperparathyroidism
(2) following a total thyroidectomy if a parathyroid gland is identified
Situation to be explained:
(1) There is a wide swing in serum parathyroid hormone concentrations for no apparent reason.
(2) The swing in values is not accompanied by changes in serum calcium or alkaline phosphatase.
Investigation:
(1) Identify which blood samples were drawn from the left arm and from the right arm.
(2) Identify which arm received the parathyroid tissue implant.
If the high values for parathyroid hormone are associated with blood samples drawn from the arm with the implant, then the explanation is passive venous backflow of hormone from the implant behind the tourniquet. In this situation blood for parathyroid levels should be drawn from the opposite arm.
The swing would not be noticed if:
(1) parathyroid tissue was embedded in both the left and right forearms (unless one of the transplants failed)
(2) blood is drawn only from one arm
If parathyroid tissue was implanted in both arms, then blood sampling should be done from an alternative site.
