The purpose of this study is to evaluate whether addition of bemiparin, once daily in icodextrin solution for peritoneal dialysis for 16 weeks, increases the peritoneal capacity for ultrafiltration and/or reduces creatinine transport in peritoneal dialysis patients presenting functional disorders related to ultrafiltration deficit and/or high transport.

Peritoneal dysfunction is a common complication in patients in stable treatment with peritoneal dialysis. This peritoneal dysfunction is defined by an elevated creatinine transport and lowered standardized ultrafiltration capacity. The aim of this study is to evaluate the efficacy of the addition of bemiparin to icodextrin solution in patients in peritoneal dialysis with peritoneal transport disorders. The eligible patients are randomly assigned to receive the icodextrin solution with bemiparin or icodextrin solution without bemiparin.

Inclusion Criteria:

1. Patients over 18 years old, of either sex, who have given their informed consent to participate in the study.
2. Patients in stable treatment with peritoneal dialysis for more than 6 weeks who present peritoneal dysfunction defined by capacity for standardized ultrafiltration (3.86% glucose maintained in the peritoneum for 4 hours) less than 600 ml and/or elevated creatinine transport (defined by D/P of creatinine higher than 0.65 after 4 hours).
3. Patients treated with icodextrin solution for peritoneal dialysis for at least one month before their inclusion.
4. Patients in whom the remaining dialyzing liquids used in their PD contain glucose and GDP (glucose degradation products).

Exclusion Criteria:

1. Peritonitis in the past 2 months.
2. Patients with bleeding at the time of inclusion, or patients with a history of clinically evident bleeding episodes and/or with increased bleeding due to any other homeostatic alteration that contradicts anticoagulant treatment and/or in the past two months have presented at least one of the following situations: active hemorrhaging or organic lesions susceptible to bleeding (e.g. active peptic ulcer, hemorrhagic cerebrovascular accident, or aneurysms).
3. Major surgery in the past month.
4. Known hypersensitivity to low molecular weight heparin (LMWH), heparin or substances of porcine origin.
5. Known hypersensitivity to icodextrin.
6. Patients treated with systemic anticoagulation.
7. Patients with congenital or acquired bleeding diathesis.
8. Damage to, or surgical interventions of, the central nervous system, eyes or ears within the past 2 months.
9. Acute bacterial endocarditis or slow endocarditis.
10. Patients with a history of heparin-associated thrombocytopenia.
11. Patients with hepatic insufficiency (with values of AST and/or ALT > 5 times the normal value established in the reference range of the local hospital laboratory).
12. Severe arterial hypertension (systolic blood pressure over 200 mmHg and/or diastolic blood pressure over 120 mmHg).
13. Patients with inability or suspected inability to comply with treatment and/or complete the study.
14. Patients who are participating in another clinical trial or have done so in the past 30 days.
15. Patients with a life expectancy less than 6 months.
16. Women who are pregnant, breast-feeding or fertile women who are not using an effective contraceptive method.