Oral Presentation 5th International Symposium on Phaeochromocytoma and Paraganglioma 2017

Optimized procedures for diagnostic testing for pheochromocytomas/paragangliomas in patients with chronic kidney disease (#30)

Christina Pamporaki 1 , Aleksander Prejbisz 2 , Frank Pistrosch 1 , Mirko Peitzsch 3 , Steffen Bischoff 4 , Petra Mueller 4 , Iris Meyer 5 , Doreen Reimann 6 , Andrzej Januszewicz 2 , Carola Kunath 1 , Jacques Lenders 7 , Graeme Eisenhofer 3 , Jens Passauer 1
  1. Department of Internal Medicine III, Uniklinikum Carl Gustav Carus at the TU Dresden, Dresden, Sachsen, Germany
  2. Department of Hypertension, Institute of Cardiology, Warsaw, Poland
  3. Institute of Clinical Chemistry and Laboratory Medicine, University Hospital Carl Gustav Carus at the TU Dresden, Dresden, Sachsen, Germany
  4. Nephrologische Gemeinschaftpraxis, Dresden, Germany
  5. Dialysis Center, Heidenau, Germany
  6. Kidney/Hypertension/Rheumatology Center, Dresden, Germany
  7. Department of Internal Medicine, Radboud University Medical Center, Nijmegen, The Netherlands

Introduction:

Diagnosis of pheochromocytomas/paragangliomas in patients with chronic kidney disease (CKD) is troublesome.

Aims:

Establish optimum pre-analytical procedures for blood sampling for measurements of metanephrines and 3-methoxytyramine in patients receiving hemodialysis and optimized reference intervals for patients with stage III-IV CKD or receiving hemodialysis (HD).

Methods:

Blood was sampled before and after dialysis (including different sampling sites) in 30 patients receiving hemodialysis. Plasma concentrations of metanephrines and 3-methoxytyramine were also measured in 226 patients with CKD (79 stage III, 40 stage IV and 108 stage V) and compared to 173 subjects of an aged-matched reference population.

Results:

Among patients on hemodialysis, plasma normetanephrine concentrations were significant lower (P<0.0001) and metanephrine concentrations significantly higher (P<0.0001) in shunt than in venous blood, with no significant differences for 3-methoxytyramine. Normetanephrine, metanephrine and 3-methoxytyramine concentrations, both in shunt and venous blood, were lower at the end than before dialysis (P<0.0001). Compared with the reference population, upper cut-offs of reference intervals (97.5% percentiles) for normetanephrine, metanephrine and 3-methoxytyramine were respectively 14%, 22% and 41% higher in patients with stage III CKD and 34%, 21% and 75% higher in patients with stage IV CKD or HD. Due to the high concentrations of 3-methoxytyramine in patients with chronic kidney disease, CKD specific cut-offs were assessed only for metanephrines.

Conclusion:

These data establish optimized reference intervals for plasma metanephrines for patients with stage III-IV CKD or HD that are useful for minimizing false-positive results. In particular, using CKD-specific cut offs, it can be expected that the proportion of false positive results would fall from 7.6% to 2.5% for patients with stage III CKD and from 22.9% to 4% for stage IV CKD or HD. We also show that blood sampling in patients receiving hemodialysis is most appropriate at the end of hemodialysis and from the dialysis shunt.