Utilidad del propéptido amino-terminal del procolágeno tipo 1 (P1NP) como marcador de remodelado óseo en el paciente sometido a trasplante renal / Use of procollagen type 1 n-terminal propeptide (P1NP) as a marker of bone remodelling in renal transplant patients

Introducción y objetivo. El propéptido aminoterminal del procolágeno tipo I (P1NP) es un marcador de formación ósea que se altera en afecciones óseas tales como la osteoporosis. El objetivo de este estudio es ver la utilidad del marcador en el diagnóstico de la osteoporosis en una población de pacientes sometidos a un trasplante renal (TR). Material y métodos. Noventa pacientes sometidos a un TR (60 varones, 30 mujeres) con una edad media±desviación estándar (DE) de 55±15 años. Se determinó en suero P1NP, creatinina, paratirina (PTH) y vitamina D, en situación pretrasplante, a los 3 meses y al año. Se estimó el filtrado glomerular con la fórmula MDRD abreviado y se registró la terapia inmunosupresora. Se realizó una densitometría ósea a los 3 meses del trasplante. Según los criterios de la Organización Mundial de la Salud se clasificó la muestra en población con masa ósea baja (T-score<−1 DE) y población normal (T-score≥−1 DE). Resultados. No se observó correlación entre la concentración de P1NP y la función renal. Un 64% de los pacientes presentaron una masa ósea baja. El paciente con densidad mineral ósea disminuida presentaba unos valores de P1NP en situación pretrasplante mayores, respecto a los pacientes con masa ósea normal. El análisis de regresión logística puso de manifiesto que P1NP (p=0,028; odds ratio=10,755) podría ser un marcador de masa ósea baja independiente de la edad, el sexo, la dosis de glucocorticoides y la PTH (covariables en el estudio). Conclusiones. El P1NP es un buen marcador para estimar el estado óseo en el paciente renal. El valor de P1NP en situación pre-trasplante sería indicativo de un mayor riesgo de presentar una masa ósea disminuida (AU)

Introduction and objective. Type I procollagen N-terminal propeptide (P1NP) is a marker of bone formation which is altered in bone diseases such as osteoporosis. The objective of this study was to evaluate the use of this marker in the diagnosis of osteoporosis in patients who undergo a renal transplant. Material and methods. Ninety RT (renal transplant) patients (60 men, 30 women) with a mean age of 55±15 years were evaluated. Serum P1NP, creatinine, parathyroid hormone (PTH), and vitamin D were measured at baseline and at 3 months and 1 year after transplantation. The glomerular filtration rate was estimated using the Modification of Diet in Renal Disease (MDRD) formula and immunosuppression therapy was recorded. A bone densitometry scan was performed 3 months after transplant. The patients were classified,according to WHO guidelines, into two populations: a group with low bone mass (T-score<−1SD) and a normal group (T-score≥−1SD). Results. No correlation was observed between P1NP conentrations and kidney function. A low bone mass was seen in 64% of the RT patients. Patients in the group with low bone mass had higher pretransplant levels of P1NP compared to those in the normal group. The logistic regression analysis showed that P1NP (P=.028; OR=10.755) could be a marker of low bone mass, regardless of age, sex, glucosteroid dose and PTH (covariables in the study). Conclusions. P1NP is a good marker for estimating bone status in renal transplanted patients. Pretransplant P1NP values could be indicative of a higher risk of having a decreased bone mass (AU)

Evaluation of the equations to estimate the glomerular filtration rate in kidney transplant recipients.

This study assessed the performance of three methods for estimating glomerular filtration rate (GFR) in kidney transplant patients: the Cockcroft-Gault formula, the modification of diet in renal disease (MDRD) method, and the four-variable modification of diet in renal disease (four-variable MDRD), both as an overall estimate and as related to clinical disease stage. We analyzed data from 136 renal transplant patients including 84 men in an overall age range of 28 to 76 years. Patients were categorized into three groups according to GFR as determined by the arithmetical mean of the last four creatinine clearance determinations after outlying values had been excluded: group 1, estimated GFR of <30 mL/min (n = 26); group 2, estimated GFR of 30 to 60 mL/min (n = 63);, and group 3, estimated GFR >60 mL/min (n = 33). Fourteen patients were excluded from the analysis because of a high variability between their creatinine clearance determinations. Estimated GFRs using the Cockroft-Gault, MDRD, and four-variable MDRD formulae were compared with GFRs as measured by creatinine clearance. Statistically significant correlations were observed for all three formulae for the overall series and for individual clinical groups. Hence, we concluded that all equations had a similar capacity to predict the GFR. In addition, because of the clear, significant correlation between the MDRD and the four-variable MDRD (r = .992; P = .0001), we believe that the four-variable MDRD can substitute for the MDRD for clinical purposes.