The study aims to describe the biochemical coagulation profile and investigate the effect of Low molecular weight heparin and Apixaban on this profile in patients with nephrotic syndrome.

The initial part of the study is a prospective cross-sectional study which will describe the biochemical coagulation profile in nephrotic patients. It will include 60 patients with nephrotic syndrome and data from 50 anonymous blood donors matched in age and gender for comparison.

The second part of the study is an open-label, controlled, non-randomized, interventional clinical trial consisting of 3 groups of patients with nephrotic syndrome or atrial fibrillation treated with either Dalteparin or Apixaban. The study participant is expected to be in stable condition after 4 full days of treatment. For administrative reasons, the final biochemical tests are performed on day 4, 5, 6 or 7 described as day 4 in this protocol.

• Group A: Up to 50 patients with nephrotic syndrome treated with injection Dalteparin 200 Units/kg subcutaneous once a day for 4 days
• Group B: 10 patients with nephrotic syndrome and membranous nephropathy treated with Apixaban 5 mg twice daily for 4 days.
• Group C: 10 patients with atrial fibrillation and no kidney disease treated with Apixaban 5 mg twice daily for 4 days.

Patients participating in the initial part of the study will be included in det second part (Group A) if they meet the inclusion criteria. If the patient is diagnosed with membranous nephropathy it is possible to be included in the initial part as well as the second part (Group A and B).

Inclusion Criteria: Nephrotic patients - no intervention

• Age 18-79 years
• Estimated Glomerular Filtration Rate (eGFR) > 49 mL/min/1.73 m2
• P-albumin < 30 g/L
• U-Albumin excretion > 2.2 g/day
• Known glomerular disease including membranous nephropathy, which may cause nephrotic syndrome or diagnostically unresolved nephrotic syndrome with a planed kidney biopsy.

Inclusion Criteria: Nephrotic patients treated with Dalteparin

• Age 18-79 years
• eGFR > 49 mL/min/1.73 m2
• P-albumin < 25 g/L
• U-Albumin excretion > 2.2 g/day
• Known glomerular disease including membranous nephropathy, which may cause nephrotic syndrome or diagnostically unresolved nephrotic syndrome with a planed kidney biopsy.

Inclusion Criteria: Nephrotic patients treated with Apixaban

• Age 18-79 years
• eGFR > 49 mL/min/1.73 m2
• P-albumin < 25 g/L
• U-Albumin excretion > 2.2 g/day
• Membranous Nephropathy

Inclusion Criteria: Patients with atrial fibrillation treated with Apixaban

• Age 18-79 years
• eGFR > 49 mL/min/1.73 m2
• P-albumin > 36 g/L
• U-Albumin excretion < 300 mg/day
• Atrial Fibrillation

Exclusion Criteria:

• Contraindication to Apixaban
• Contraindication to Dalteparin
• Known allergy or intolerance to Apixaban
• Known allergy or intolerance to Dalteparin
• Treatment with anticoagulation for other reasons.
• Treatment with cyclooxygenase-1-inhibitors or Adenosine Diphosphate (ADP) receptor inhibitors.
• Known acquired or congenital coagulation defect non related to nephrotic syndrome or thromboembolic disease within 3 months.
• Known diabetes mellitus.
• Lack of compliance, comorbidity or other conditions that, in the patients unfit to participate in the trial.
• Pregnancy