Al Martín de Francisco

Denosumab y enfermedad renal crónica avanzada: hipocalcemia severa con riesgo vital

potasio en el colon. El mecanismo a través del cual se aumenta la secreción colónica de potasio en estos pacientes es complejo; y depende de varios factores. Por un lado, existe un aumento de la actividad de la bomba Na+/K+ ATPasa en la membrana basolateral de la célula intestinal, que conlleva a un aumento de la concentración de potasio intracelular y a un aumento en la conductividad del potasio en células apicales. La secreción de potasio del colon también está aumentada por la aldosterona, y aunque su mecanismo no está del todo descrito, parece tener relación con un aumento en la expresión de los canales de alta conductividad del potasio (BK channels) en la membrana apical de la célula intestinal3. Konowa et al., publicaron un caso4 en el año 2013, en el cual se describe una paciente con IRCT en programa de hemodiálisis que se somete a resección de la unión íleo-cecal y una ileostomía temporal, tras lo cual la paciente desarrolla una hiperpotasemia, que revierte tras la reanastomosis del colon. Diversos estudios in vitro e in vivo, han demostrado con técnicas de inmunohistoquímica que existe una mayor expresión de los BK channels en pacientes con IRCT, que en aquellos pacientes con función renal normal; en los que predomina la expresión de canales de baja o mediana conductividad de potasio. En resumen, la secreción de potasio en el tracto gastrointestinal es un mecanismo complejo y fundamental para mantener la homeostasis del mismo en pacientes con IRCT. Nuestro caso demuestra la importancia de la secreción de potasio en el colon en pacientes con IRCT. b i b l i o g r a f í a

Evolución del índice de resistencia a darbepoetina alfa en pacientes dializados que cambian de administración semanal a quincenal en la práctica clínica

BACKGROUND Darbepoetin alpha (DA) administered every-other-week (Q2W) is efficacious and safe for the treatment of anaemia in patients undergoing dialysis. There are no data available regarding the evolution of erythropoietic resistance index (ERI) after conversion from weekly (QW) to Q2W administration of DA in clinical practice. MATERIAL AND METHODS Multicenter, observational, retrospective, 16-weeks study, which included stable patients undergoing dialysis who were converted from DA QW to DA Q2W in clinical practice. Conversion was done according to product specifications (duplicating QW dose). The ERI to DA was calculated by dividing the weekly DA dose per kilogram of weight (microg/wk.kg)*200 by the Hb level (g/dL). ERI evolution with time was evaluated by multivariate repeated measures ANOVA, adjusting for significant covariates. RESULTS A total of 202 patients were included (137 patients undergoing haemodialysis [HD], intravenous (IV) DA, and 65 patients receiving peritoneal dialysis [PD], subcutaneous DA). Mean (SD) age was 66 (17) years; 61% of patients were men. Large intercentre variability was observed for the ERI at conversion time (coefficient of variation of 88%, p < 0.001 for differences between centres). In the univariate analysis, predictor factors for high baseline ERI were low albumin level (r = -0.29; p =0.001), HD (mean ERI of 9.3 [8.4] vs 6.8 [4.6] for PD; p = 0.005), or previous cardiovascular disease (9.9 [8.7] vs 7.4 [6.3] for patients without history; p =0.025). During the follow up, the ERI was slightly increased in HD patients (9.3 [8.4] at conversion vs 11.1 [7.3] at 16 weeks; p < 0.05), and remained stable in PD patients (6.8 [4.6] vs 6.7 [4.0], respectively; NS). In the multivariate analysis, there were no significant differences in ERI during the 16 weeks post-conversion after adjusting for albumin levels and centre (adjusted baseline mean [95% CI] of 10.0 [8.7-11.4] vs 10.5 [9.3-11.8] at 16 weeks, adjusted change of +0.5 [-0.67; 1.67]; NS). After 16 weeks, only 7 patients (3.5%) had discontinued Q2W administration. CONCLUSIONS Extension from weekly to once every other-week darbepoetin alpha allows to simplify anaemia treatment without increasing the resistance index, regardless of dialysis type. The multivariate analysis shows that, after adjusting by center and inflammation/nutritional status, there were no changes in the response to darbepoetin alpha during the first 16 weeks after conversion in clinical practice.