Interpretation of serum parathyroid hormone concentrations in dialysis patients: what do the KDIGO guidelines change for the clinical laboratory?

Abstract

The Kidney Disease: Improving Global Outcomes (KDIGO) have recently replaced the K/DOQI guidelines to help nephrologists in diagnosing, treating and monitoring chronic kidney disease mineral and bone disorders (CKD-MBD). Here, we comment on the KDIGO recommendations concerning the interpretation of parathyroid hormone (PTH) concentrations in dialysis patients: ''In patients with CKD stage 5D, we suggest maintaining iPTH in the range of approximately two to nine times the upper normal limit of the assay. We suggest that marked changes in PTH concentrations in either direction within this range prompt an initiation or change in therapy to avoid progression to concentrations outside of this range''. Our comments concern the interpretation of PTH in dialysis patients, but also the more global problem of establishing normal values for PTH. Clin Chem Lab Med 2010;48:769-74.

Serum PTH reference values established by an automated third-generation assay in vitamin D-replete subjects with normal renal function: consequences of diagnosing primary hyperparathyroidism and the classification of dialysis patients

“…Second-generation assays cross-react with N-terminal truncated PTH fragments , while third-generation assays do not detect 7-84 PTH but measure, in addition to 1-84 PTH, a post-translational form called amino-PTH, that is overproduced in many patients with parathyroid carcinomas (1,2). Guidelines for the diagnosis of asymptomatic primary hyperparathyroidism (PHPT) (3), and also the KDIGO guidelines (4), emphasize that secondand third-generation PTH assays have similar clinical values for the diagnosis of PHPT and for the follow-up of chronic kidney disease (CKD)-related mineral and bone disorders.…”

Parathyroid hormone measurement in chronic kidney disease – an evolving issue for the nephrologist and the clinical laboratorist: minireview

“…Therefore, KDIGO guidelines 2009 recommend that they should continue to be used in routine clinical practice at present, also in consideration that "third-generation" PTH assays have not been shown convincingly to improve the predictive value for the diagnosis of underlying bone disease. (35) Moreover, at the moment of the KDIGO guidelines production, the only current available third-generation assay was an IRMA, available to a limited number of laboratories only. (35) Furthermore, KDIGO guidelines cautiously state that "in patients with CKD stages 3-5 not on dialysis, the optimal PTH level is not known".…”

“…(35) Moreover, at the moment of the KDIGO guidelines production, the only current available third-generation assay was an IRMA, available to a limited number of laboratories only. (35) Furthermore, KDIGO guidelines cautiously state that "in patients with CKD stages 3-5 not on dialysis, the optimal PTH level is not known". (16) In patients with CKD stage 5D, KDIGO guidelines suggest maintaining PTH levels in the range of approximately two to nine times the upper normal limit for the assay.…”

“…In this way, target levels of PTH in stage 5D are suitable to the specific method applied in each laboratory. (35) In 1999, the first third-generation PTH assay was developed by Scantibodies Laboratory, called whole PTH assay. (36) Other names for this generation of assays were bio-intact or Ca-PTH or 1-84 PTH.…”

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“…Ces valeurs hautes recommandées prennent en compte le déséquilibre en faveur des fragments C-terminaux en cas d'IRC [27], mais également la résistance osseuse à la PTH [19]. …”