The effect of hemodialysis on liver stiffness measurement: a single-center series.

BACKGROUND/AIMS: The noninvasive measurement of liver stiffness using transient elastography (TE) is increasingly being used alongside liver biopsy. However, several conditions may lead to higher liver stiffness values without reflecting more fibrosis. Such conditions (e.g. hepatitis, cholestasis, heart failure, mechanical ventilation) limit the interpretation of liver stiffness measurements. The influence of hemodialysis on the measurement of liver stiffness has not been investigated to date. Here, we analyzed liver stiffness assessed by fibroscan in 17 patients directly before and after a hemodialysis session. PATIENTS AND METHODS: Measurement of hepatic stiffness by TE was carried out using the Fibroscan device with the 'M probe' directly before and directly after one session of hemodialysis. Each measurement consisted of at least 10 individual and valid measurements, with a success rate of at least 60%, and an interquartile range of less than 25%. All measurements were carried out by one investigator not involved in patient management. RESULTS: Before dialysis, the median TE was 5.1 kPa (2.8-17 kPa). Ten patients had values below the threshold of 7.1 kPa and seven patients had TE>7.1 kPa. The median net fluid withdrawal by hemodialysis was 2.5 l (0.4-3.1 l) and did not differ between patients. After dialysis, the TE median was 7.4 kPa (3.5-12.5 kPa) and had changed in all patients except one. Liver stiffness increased significantly when the initial TE was lower than 7.1 kPa (P=0.05), but not when the initial TE was higher than 7.1 kPa. Furthermore, the magnitude of the change in TE after hemodialysis correlated inversely with the liver stiffness before hemodialysis (P=0.03) and with spleen length measured by ultrasound (P=0.03). CONCLUSION: This study is the first to report on the influence of hemodialysis on liver stiffness measurement. In contrast to previous reports, liver stiffness might increase after fluid withdrawal if patients do not show significant fibrosis. We conclude that before dialysis, TE possibly better differentiates between patients with or without significant fibrosis.

Pulmonary hypertension in patients with chronic kidney disease on dialysis and without dialysis: results of the PEPPER-study.

Pulmonary hypertension (PH) is common in patients with dialysis-dependent chronic kidney disease and is an independent predictor of mortality. However, specific hemodynamics of the pulmonary circulation, changes induced by hemodialysis and characterization into pre- or postcapillary PH have not been evaluated in patients with chronic kidney disease. We assessed consecutive patients with end-stage chronic kidney disease in WHO FC ≥ II with dyspnea unexplained by other causes on hemodialysis (group 1, n = 31) or without dialysis (group 2, n = 31) using right heart catheterization (RHC). In group 1, RHC was performed before and after dialysis. In end-stage chronic kidney disease, prevalence of precapillary PH was 13% (4/31), and postcapillary PH was discovered in 65% (20/31). All four cases of precapillary PH were unmasked after dialysis. In group 2, two cases of precapillary PH were detected (6%), and postcapillary PH was diagnosed in 22 cases (71%). This is the first study examining a large cohort of patients with chronic kidney disease invasively by RHC for the prevalence of PH. The prevalence of precapillary PH was 13% in patients with end-stage kidney disease. That suggests careful screening for precapillary PH in this selected patient population. RHC should be performed after hemodialysis.