Laura Rodríguez-Osorio1, Concepción de la Piedra2, Mercedes Rubert2, Marta Martín-Fernández2, María Luisa González Casaus3, Carolina Gracia-Iguacel1, Jesús Egido4, Ricardo Villa-Bellosta5, Emilio González Parra6. 1. Servicio de Nefrología, Fundación Jiménez Díaz, Madrid, España; Instituto de Investigación Sanitaria, Fundación Jiménez Díaz (IIS-FJD), Madrid, España. 2. Servicio de Laboratorio de Bioquímica, Fundación Jiménez Díaz, Madrid, España. 3. Servicio de Análisis Clínicos, Hospital Gómez Ulla, Madrid, España. 4. Servicio de Nefrología, Fundación Jiménez Díaz, Madrid, España; Instituto de Investigación Sanitaria, Fundación Jiménez Díaz (IIS-FJD), Madrid, España; Servicio de Nefrología, Fundación Jiménez Díaz, Universidad Autónoma de Madrid, Madrid, España. 5. Instituto de Investigación Sanitaria, Fundación Jiménez Díaz (IIS-FJD), Madrid, España. 6. Servicio de Nefrología, Fundación Jiménez Díaz, Madrid, España; Instituto de Investigación Sanitaria, Fundación Jiménez Díaz (IIS-FJD), Madrid, España; Servicio de Nefrología, Fundación Jiménez Díaz, Universidad Autónoma de Madrid, Madrid, España. Electronic address: egonzalezpa@senefro.org.
Abstract
Parathormone plays a key role in controlling mineral metabolism. PTH is considered a uremic toxin causing cardiovascular damage and cardiovascular mortality in dialysis patients. There are two different assays to measure PTH called 2nd generation or intact PTH (iPTH) and 3rd generation or bioPTH (PTHbio). OBJECTIVE: To evaluate the differences in mortality of dialysis patients between both assays to measure PTH, as well as the possible prognostic role of the PTHbio/iPTH ratio. METHODS: 145 haemodialysis patients were included with 2-year monitoring including baseline laboratory test and annually thereafter. RESULTS: 21 patients died in the first year and 28 in the second. No correlation was found between PTH, PTHbio and PTHbio/iPTH ratio with mortality. Both PTH have a perfect correlation between them and correlate similarly with other molecules of the mineral metabolism. The extreme baseline values of PTH are those of higher mortality. In survival by iPTH intervals (according to guidelines and COSMOS study), a J curve is observed. When iPTH increases, the ratio decreases, possibly when increasing fragments no. 1-84. There is no greater prognostic approximation on mortality with PTHbio than PTHi. There was also no difference in mortality when progression ratio PTHbio/PTHi was analysed. CONCLUSIONS: We didn't find any advantages to using bioPTH vs. PTHi as a marker of mortality. BioPTH limits of normality must be reevaluated because its relationship with iPTH is not consistent. Not knowing these limits affects its prognostic value.
Parathormone plays a key role in controlling mineral metabolism. PTH is considered a uremic toxin causing cardiovascular damage and cardiovascular mortality in dialysis patients. There are two different assays to measure PTH called 2nd generation or intact PTH (iPTH) and 3rd generation or bioPTH (PTHbio). OBJECTIVE: To evaluate the differences in mortality of dialysis patients between both assays to measure PTH, as well as the possible prognostic role of the PTHbio/iPTH ratio. METHODS: 145 haemodialysis patients were included with 2-year monitoring including baseline laboratory test and annually thereafter. RESULTS: 21 patients died in the first year and 28 in the second. No correlation was found between PTH, PTHbio and PTHbio/iPTH ratio with mortality. Both PTH have a perfect correlation between them and correlate similarly with other molecules of the mineral metabolism. The extreme baseline values of PTH are those of higher mortality. In survival by iPTH intervals (according to guidelines and COSMOS study), a J curve is observed. When iPTH increases, the ratio decreases, possibly when increasing fragments no. 1-84. There is no greater prognostic approximation on mortality with PTHbio than PTHi. There was also no difference in mortality when progression ratio PTHbio/PTHi was analysed. CONCLUSIONS: We didn't find any advantages to using bioPTH vs. PTHi as a marker of mortality. BioPTH limits of normality must be reevaluated because its relationship with iPTH is not consistent. Not knowing these limits affects its prognostic value.