Managing secondary hyperparathyroidism in dialysis patients should be a rewarding aspect of nephrology. I thrive on complex management that involves balancing various numbers with clever treatment strategies. It is exactly what I find so exhilarating about a juicy electrolyte case in the ICU.
The principle variables in secondary hyperparathyroidism are:
- PTH
- Phosphorous
- Calcium
- low phosphorous diet
- calcium containing binders
- non-calcium binders
- calcitriol
- paricalcitol and doxercalciferol
- cinacalcet
- dialysate calcium concentration
- parathyroidectomy
And K/DOQI provided cleanly laid out treatment goals:
- PTH 150-300
- Caclium 8.4-9.5
- Phosphorous 3.5-5.5
- Calcium x phosphorous product < 55
The numbers (0 of 3, 1 of 3, etc) refer to the number of months a patient is at the K/DOQI target in the quarter, PTH was measured only once a quarter |
The problem is that no one has performed a prospective randomized controlled trial showing these targets improve outcomes. We want to believe that the retrospective data showing a survival advantage with cinacalcet and paricalcitol are real and that the observational data showing better calcium and phosphorous (and to a smaller degree, PTH) results in better patient outcomes.
Teng et al. Survival of patients undergoing hemodialysis with paricalcitol or calcitriol therapy. N Engl J Med (2003) vol. 349 (5) pp. 446-56 |
Block et al. Mineral metabolism, mortality, and morbidity in maintenance hemodialysis. J Am Soc Nephrol (2004) vol. 15 (8) pp. 2208-18 |
I love this figure from KDIGO, essentially once the PTH rises over 150 it provides no information. PTH > 300 has a positive predictive value of only 65% for high turnover disease. And don’t miss the laughably small numbers. We are basing global guidelines off of a study of less than 100 patients. From Barreto and Barreto. |
It is shameful that Abbott has not done an RCT with survival as an endpoint on Zemplar or Calcijex. They have had 20+ years to do this. Both of the other players in CKD-MBD have taken a chance at building RCT data to support there products:
- Genzyme took a poke with DCOR (RCT of sevelamer versus calcium based binders)
- Amgen is in the final countdown of EVOLVE (RCT of sensipar + usual care vs usual care)
Couldn't agree more. Well said.
Thanks
You need to get a picture up on your google profile, use the one from twitter