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EMiNEM Case #3: Answers and Discussion

EMiNEM Case #3: Answers and Discussion

  1. Switching to a non calcium based Phosphate binder may decrease Calcium levels, however, this in turn will increase PTH levels. In Ontario, this patient would not qualify for EAP approval for sevelamer as his P is not above 1.There is no evidence that switching to non calcium phosphate binders decreases mortality or has any direct changes on PTH levels.
  2. Increasing calcitriol dose would potentially decrease PTH although this patient may be resistant to calcitriol as his parathyroid glands may be hyperplastic and non responsive to more calcitriol. Furthermore, an increase in calcitriol would further increase phosphorus or calcium levels.
  3. Could be correct in certain circumstance (see below)
  4. Selected answer 

Hyperparathyroidism usually improves after transplantation, since the new kidney can excrete phosphate and produce 1,25-dihydroxyvitamin D in appropriate amounts. About 1/3 of patients develop hypercalcemia after a transplant; this persists in 7% and requires parathyroid surgery in about 2%. The PTH may continue to gradually decrease for many years after surgery.

Post transplant, management of CKD bone disease is important as patients can experience hypercalcemia and persistent hyperparathyroidism. Furthermore, post transplant bone disease also consists of osteoporosis and systemic and local derangements of the bone.

Management is based on the bone disease prior to transplantation- if patient has long standing CKD and bone disease, surgery may be warranted. However, surgery is dependent on patient. Some patients will not be suitable for surgery- high risk such as severe cardiac disease and in these cases, cinacalcet may be appropriate. (Not so in this case since the patient is on the transplant list and would have been worked up for comorbidities preventing surgery).

Parathyroidectomy should probably not be performed in the very early phase after transplant when large doses of steroids are given and when PTH theoretically might be a “survival factor” for the osteoblasts. Furthermore, 5 studies of patients with parathyroidectomy post transplant demonstrated a fall in GFR after the surgery. However, severe hyperparathyroidism is also a risk factor for deterioration of GFR.  Whether calcimimetics will provide better graft survival, as compared with parathyroidectomy remains to be shown.

References:

1. Tominaga Y, Matsuoka S, Uno N, Sato T.  Parathyroidectomy for Secondary Hyperparathyroidsim in the Era of Calcimimetics. Therapuetic Apheresis and Dialysis 2008;12:S21-S26.

2. Guerra R, Auyant I, Fernandez EJ, Perez MA, Bosch E, Ramirez A, Suria S, Checa MD.  Hypercalcemia secondary to persistent hyperparathuroidism in kidney transplant patients: analysis after a year with cinacalcet. J Nephrol 2011;24(1):78-82

3. Weisinger JR, Carlini RG, Rojas E, Bellorin-Font E. Bone Disease after Renal Transplantation. Clin J Am Soc Nephrol 2006;1:1300-1313.