From the Guidelines
Thrombocytopenia and proteinuria can occur together in several medical conditions, with the most likely diagnoses including thrombotic microangiopathies, systemic lupus erythematosus, antiphospholipid syndrome, and certain infections, and management depends on identifying the underlying cause through blood tests, urinalysis, and sometimes kidney or bone marrow biopsies 1.
Causes of Thrombocytopenia and Proteinuria
Thrombocytopenia, characterized by low platelet counts below 150,000/μL, may result from:
- Decreased platelet production
- Increased destruction
- Splenic sequestration Common causes include:
- Bone marrow disorders (leukemia, aplastic anemia)
- Immune-mediated destruction (ITP, drug-induced)
- Infections (HIV, sepsis)
- Pregnancy complications Proteinuria, the presence of excess protein in urine (>150 mg/day), often indicates kidney damage.
Diagnosis and Management
When thrombocytopenia and proteinuria occur together, diagnosis and management depend on identifying the underlying cause, with treatment targeting the specific condition, ranging from:
- Plasmapheresis for TTP
- Immunosuppressants for autoimmune disorders
- Supportive care including blood pressure control and sometimes platelet transfusions for severe thrombocytopenia The use of ACEi or ARB has been associated with proteinuria reduction and a reduction in GFR decline in patients with proteinuria ≥1 g/day, and together with strict BP targets, should be instituted in all patients who are at higher risk for progression 1.
Key Considerations
- Reduction of proteinuria to ≤1 g/day is associated with a more favorable prognosis irrespective of whether the initial proteinuria was ≥3 g or of lesser degrees
- BP is also an important risk factor, and if the proteinuria in patients is ≥1 g/day, a target BP ≤125/75 mm Hg has been recommended
- The threshold level of proteinuria that heralds risk is uncertain, but most studies have shown the threshold to be 1 g/day (especially time-averaged values) 1
From the Research
Causes of Thrombocytopenia
- Decreased platelet production 2
- Increased destruction 2
- Splenic sequestration 2
- Dilution or clumping 2
- Immune thrombocytopenia 2
- Drug-induced thrombocytopenia 2
- Hepatic disease 2
- Heparin-induced thrombocytopenia 2
- Thrombotic microangiopathies 2
- Hemolysis, elevated liver enzymes, and low platelet count (HELLP) syndrome 2
- Viral hepatitis, including hepatitis C virus (HCV) infection 3
Causes of Proteinuria
- Renal disease 4, 5, 6
- Systemic disease 4
- Functional proteinuria, which may occur in disorders with altered renal hemodynamics 4
- Idiopathic transient proteinuria 4
- Idiopathic intermittent proteinuria 4
- Orthostatic proteinuria 4
- Persistent isolated proteinuria 4
- HIV-associated nephropathy 5
- Non-HIV-associated nephropathy focal segmental glomerulosclerosis 5
- Membranoproliferative glomerulonephritis 5
- AA Amyloid 5
- Diabetic nephropathy 5
Relationship between Thrombocytopenia and Proteinuria
- Thrombocytopenia may be associated with proteinuria in certain conditions, such as HIV-associated nephropathy 5 and hepatitis C virus (HCV) infection 3
- Proteinuria may contribute to progression of underlying pathology, including thrombocytopenia, through various mechanisms, such as toxic effects on renal cells, secondary hyperlipidemia, and hyperaggregability of platelets 6