Cryoglobulinaemia

Cryoglobulinaemia refers to the presence of cryoglobulins — immunoglobulins that precipitate reversibly at temperatures below 37°C and dissolve on rewarming. When symptomatic, cryoglobulins cause cryoglobulinaemic vasculitis — a small-vessel immune complex vasculitis affecting skin, joints, peripheral nerves, and kidneys. Cryoglobulinaemia is classified into three types (Brouet classification): Type I (monoclonal, associated with haematological malignancy), Type II (mixed with monoclonal RF component, most commonly HCV-associated), and Type III (polyclonal, associated with autoimmune diseases and infections). Hepatitis C virus (HCV) is the most common cause of mixed cryoglobulinaemia globally.

Australian Context

Hepatitis C remains prevalent in Australia despite highly effective direct-acting antiviral (DAA) therapy, with an estimated 117,000 Australians living with chronic HCV in 2022. HCV-associated mixed cryoglobulinaemia (Type II) is the most clinically significant form seen in Australian rheumatology practice. The availability of PBS-funded DAA therapy (elbasvir/grazoprevir, glecaprevir/pibrentasvir, sofosbuvir/velpatasvir) has transformed HCV-associated cryoglobulinaemic vasculitis management, with antiviral therapy now the cornerstone of treatment.

Pathophysiology

Cryoglobulin Types and Associations

Type I (Monoclonal): Single monoclonal immunoglobulin (IgM or IgG) — associated with multiple myeloma, Waldenström macroglobulinaemia, B-cell lymphoma. Causes hyperviscosity and vascular occlusion rather than immune complex vasculitis.
Type II (Mixed — Monoclonal RF): Monoclonal IgM with rheumatoid factor activity + polyclonal IgG — strongly associated with HCV (80–90% of cases). IgM-IgG complexes deposit in vessel walls causing complement-mediated vasculitis.
Type III (Mixed — Polyclonal): Polyclonal IgM + polyclonal IgG — associated with SLE, Sjögren syndrome, RA, other chronic infections (HIV, HBV, EBV). Less severe clinically than Type II.

Vasculitis Mechanism

In mixed cryoglobulinaemia, IgM-IgG immune complexes precipitate in vessel walls at cool peripheral temperatures (skin, digits, ears). Complement activation (classical pathway, consuming C3 and C4) drives leukocytoclastic vasculitis. Low C4 is a characteristic finding and useful diagnostic marker. Cryoglobulin-stimulated B cells (driven by HCV E2 protein binding to CD81) produce rheumatoid factor, perpetuating immune complex formation.

Clinical Presentation

Meltzer Triad (Mixed Cryoglobulinaemia)

The classic Meltzer triad of purpura, weakness, and arthralgia occurs in approximately 30% of patients with mixed cryoglobulinaemia. Many patients have only one or two features.

Purpura (70–90%): Palpable, non-thrombocytopenic purpura predominantly affecting legs, thighs, and buttocks; worse in cold weather and after prolonged standing; may ulcerate
Arthralgia/Arthritis (70–80%): Symmetric, non-erosive; affects hands, knees, ankles; similar to RA in distribution but non-destructive
Weakness/Fatigue (50%): Profound fatigue often out of proportion to objective findings; may be disabling
Peripheral neuropathy (40–60%): Sensorimotor neuropathy, mononeuritis multiplex; may be painful and debilitating
Membranoproliferative glomerulonephritis (20–30%): Haematuria, proteinuria, hypertension, nephrotic syndrome; may progress to CKD
Raynaud phenomenon, acrocyanosis: Cold-induced peripheral ischaemia from cryoprecipitation in small vessels

Type I Cryoglobulinaemia

Predominantly hyperviscosity syndrome — headache, visual disturbance, epistaxis, digital ischaemia, Raynaud phenomenon — rather than vasculitis. Urgent plasmapheresis may be needed for severe hyperviscosity.

Investigations

Essential
Cryoglobulin Detection
Blood collected in pre-warmed tubes at 37°C and transported immediately to lab. Refrigerate sample at 4°C for 7 days and observe for precipitation. Sensitivity depends critically on correct sample handling. Type determined by immunofixation electrophoresis.
Essential
Complement (C3, C4, CH50)
Low C4 (often profoundly low) with normal or mildly low C3 is characteristic of mixed cryoglobulinaemia — reflects classical pathway consumption by immune complexes. Useful for diagnosis and disease activity monitoring.
Essential
HCV Serology and RNA (PCR)
Mandatory in all cryoglobulinaemia — HCV is the most common cause of mixed cryoglobulinaemia. HCV RNA quantification for treatment planning. Anti-HCV antibody may be falsely negative in severely immunosuppressed patients — request HCV RNA directly if suspicion high.
Essential
Rheumatoid Factor
Positive RF (IgM anti-IgG) in Type II cryoglobulinaemia. Very high titres (>1:256) are characteristic. Low-titre RF is common in Type III. Useful in conjunction with complement levels.
Available
Serum Protein Electrophoresis and Immunofixation
Identifies monoclonal component in Type I and II. Quantifies paraprotein level. Baseline for haematological malignancy assessment.
Referral
Skin or Renal Biopsy
Skin biopsy: leukocytoclastic vasculitis with IgM and IgG deposits. Renal biopsy: membranoproliferative GN with intraluminal hyaline thrombi (cryoglobulin deposits). Essential for nephritis severity grading.

Severity Assessment

MILD

Skin and Joints

Purpura, arthralgia, fatigue — no nephritis or neuropathy

Antiviral therapy for HCV (cornerstone); conservative symptomatic management

MODERATE

Neuropathy or Mild Nephritis

Peripheral neuropathy, proteinuria <1 g/day, mild renal impairment

DAA therapy for HCV + consider rituximab; nephrology referral; ACE inhibitor for proteinuria

SEVERE

Nephritis or Organ-Threatening

MPGN with nephrotic syndrome, RPGN, severe neuropathy, digital ischaemia

Rituximab + high-dose corticosteroids ± plasma exchange; DAA after vasculitis controlled; urgent nephrology

Treatment Strategy

HCV-Associated Cryoglobulinaemia: DAA Therapy (First-Line)

Direct-acting antiviral (DAA) therapy targeting HCV is the cornerstone of treatment for HCV-associated mixed cryoglobulinaemia. Achieving sustained virological response (SVR — undetectable HCV RNA 12 weeks after treatment completion) leads to cryoglobulinaemia remission in 70–90% of cases. All HCV-positive patients with cryoglobulinaemia should receive DAA therapy. PBS-funded regimens include glecaprevir/pibrentasvir (8–12 weeks) and sofosbuvir/velpatasvir (12 weeks). Refer to hepatology or infectious disease for HCV genotyping and DAA selection.

Immunosuppressive Therapy

For severe or organ-threatening cryoglobulinaemic vasculitis (RPGN, severe neuropathy, digital ischaemia), immunosuppression is needed alongside or before DAA therapy. Rituximab (375 mg/m² weekly × 4 or 1000 mg × 2 doses) is the preferred agent for HCV-associated and non-HCV mixed cryoglobulinaemia — targets CD20+ B cells producing pathogenic IgM RF. Corticosteroids (prednisolone 0.5–1 mg/kg/day) for rapid disease control. Plasma exchange for acute life-threatening disease (digital gangrene, RPGN, hyperviscosity).

Non-HCV Cryoglobulinaemia

Treat underlying cause: rituximab for haematological causes (Type I) and B-cell lymphoma-associated Type II; immunosuppression for autoimmune-associated Type III (prednisolone ± azathioprine or MMF). Type I associated with myeloma: treat underlying myeloma in consultation with haematology.

Directed Therapy

💊

Glecaprevir / Pibrentasvir

Maviret® · Pangenotypic DAA · HCV

Adult Dose3 tablets (300 mg/120 mg) once daily with food

PaediatricWeight-based; approved ≥3 years

RouteOral

FrequencyOnce daily

Duration8–12 weeks (treatment-naïve); 12–16 weeks (treatment-experienced)

Renal Adj.Safe in all stages of CKD including dialysis

Hepatic Adj.Avoid in Child-Pugh B/C

PBS Status✓ PBS Listed

💉

Rituximab

MabThera®, Riximyo® · Anti-CD20 · Immunosuppression

Adult Dose375 mg/m² IV weekly × 4, OR 1000 mg IV × 2 doses (2 weeks apart)

RouteIntravenous infusion

FrequencyInduction; re-treat if relapse after HCV SVR

DurationSingle course; may repeat for refractory disease

Renal Adj.No formal adjustment required

PBS StatusPBS Authority Required

Acute Management and Specialist Referral

Acute Cryoglobulinaemic Vasculitis

Acute flares with severe organ involvement (rapidly progressive glomerulonephritis, mononeuritis multiplex, digital ischaemia) require urgent hospitalisation and rheumatology/nephrology review. Initial management focuses on immunosuppression and trigger control.

Assess Severity

Identify end-organ involvement: renal function, neurological status, skin involvement. Check cryoglobulin titre, complement levels, ANCA, anti-dsDNA.

Treat Underlying Cause

If HCV-associated: prioritise DAA therapy initiation after stabilisation. If HBV-associated: antiviral therapy. If autoimmune: optimise immunosuppression.

Immunosuppression

Methylprednisolone 0.5–1 g IV daily for 3 days for severe flare. Rituximab 375 mg/m² weekly × 4 for B-cell driven disease. Cyclophosphamide reserved for life-threatening disease.

Plasma Exchange

Plasmapheresis indicated for hyperviscosity syndrome, rapidly progressive GN, or life-threatening disease. 3–5 sessions every other day; reduces circulating cryoglobulin load acutely.

Hyperviscosity Syndrome

Type I cryoglobulinaemia may present with hyperviscosity: headache, visual disturbance, epistaxis, confusion. Urgent plasma exchange required. Avoid cold environments (triggers cryoprecipitation). Keep patient warm including IV fluids at 37°C.

🚨

Cold Precaution: All IV fluids must be warmed to body temperature. Cold blood products and IV fluids can precipitate cryoglobulins in vessels. Maintain warm environment at all times.

Monitoring and Follow-up

Laboratory Monitoring

Baseline

Cryoglobulin quantification, C3/C4/CH50, FBC, UEC, LFTs, urinalysis, HCV RNA/HBV DNA, RF, ANA, ANCA, protein electrophoresis.

During DAA Therapy

HCV RNA at weeks 4, 8, 12 of treatment. UEC and LFTs monthly. Cryoglobulin titre and complement at end of treatment.

12 Weeks Post-Treatment

Confirm sustained virological response (SVR12). Reassess cryoglobulin levels and complement. Expect improvement in complement levels and cryoglobulin titre post-SVR.

6-Monthly

Clinical assessment for vasculitis activity. Repeat complement, cryoglobulin, urinalysis. Monitor for HCC in cirrhotic patients (HCV-associated). Hepatology review annually.

Renal Monitoring

Membranoproliferative GN is the most common renal manifestation. Monitor urine protein:creatinine ratio, microscopy, GFR every 3 months. Significant proteinuria (>1 g/day) or declining GFR requires nephrology review and consider repeat biopsy. Target SBP ≤125 mmHg with ACE inhibitor or ARB if proteinuric.

Disease Activity Assessment

Birmingham Vasculitis Activity Score (BVAS) or Disease Extent Index-Cryoglobulinaemia (DEI-Cryo) can be used to track disease activity over time. Monitor skin, joint, neuropathy, and renal domains at each visit. Cryoglobulin titre does not always correlate with clinical activity.

Special Populations

👶 Paediatric Cryoglobulinaemia

Rare in childrenMost paediatric cases are type II/III associated with autoimmune disease (SLE, JIA) or infection. HCV vertical transmission may cause neonatal cryoglobulinaemia.

TreatmentAddress underlying disease. DAAs approved in children >3 years for HCV. Rituximab used off-label in paediatric autoimmune disease. Avoid cyclophosphamide where possible.

🤰 Pregnancy

HCV DAAsMost DAAs are Category D/contraindicated in pregnancy. Defer HCV treatment until after delivery if clinically stable. Ribavirin absolutely contraindicated.

RituximabAvoid in pregnancy — crosses placenta in third trimester. Use only if life-threatening vasculitis. Prednisolone is preferred for flare control during pregnancy.

Neonatal careHCV-positive mothers: test neonate at 18 months. Breastfeeding generally safe with HCV (low transmission risk) unless nipples cracked/bleeding.

🫘 Renal Impairment

DAA dose adjustmentGlecaprevir/Pibrentasvir: no dose adjustment required for any degree of renal impairment, including dialysis — preferred regimen in CKD.

RituximabNo dose adjustment required. Monitor for infection given immunosuppression in already-impaired immune function of CKD patients.

PlasmapheresisMay be required in parallel with RRT if severe GN with fluid overload. Coordinate with nephrology.

👴 Elderly Patients

Polypharmacy riskElderly patients with HCV often have comorbidities. Check drug interactions carefully with DAA regimens. Glecaprevir/Pibrentasvir generally well-tolerated.

ImmunosuppressionHigher infection risk with rituximab and corticosteroids in elderly. Ensure pneumococcal and influenza vaccination prior to rituximab. Lower threshold for Pneumocystis prophylaxis.

Aboriginal and Torres Strait Islander Health Considerations

HCV infection, a major cause of mixed cryoglobulinaemia, disproportionately affects Aboriginal and Torres Strait Islander peoples, with rates up to 5 times higher than in non-Indigenous Australians. This reflects historical injecting drug use, incarceration, and healthcare inequity. Cryoglobulinaemia may therefore be underdiagnosed in this population.

HCV Testing and Linkage to Care

Opportunistic HCV antibody and RNA testing in primary care and Aboriginal Community Controlled Health Organisations (ACCHOs). Point-of-care testing available in some remote settings. Once diagnosed, prioritise linkage to DAA therapy — available through GP prescribers under PBS S100 arrangement. Nurse-led DAA programmes in remote communities have demonstrated high SVR rates.

Cryoglobulinaemia Diagnosis

Low index of suspicion may cause diagnostic delay. Clinicians should consider cryoglobulinaemia in any HCV-positive patient with purpura, arthritis, renal disease, or peripheral neuropathy. Cryoglobulin testing requires careful sample handling (37°C transport) — liaise with pathology laboratory in advance.

Rheumatology Access

Specialist rheumatology is rarely available in remote communities. Use telehealth rheumatology consultations (MBS-funded). Shared care models with GP and ACCHO nurses. Ensure transport and accommodation support for infrequent specialist reviews.

Culturally Safe Care

Engage Aboriginal Liaison Officers and community health workers. Use culturally safe communication about HCV, addressing stigma particularly around past injecting drug use. Translated education materials and visual guides for DAA adherence. Involve family and community support in chronic disease management.

Antimicrobial Stewardship

Key Stewardship Principles

Cryoglobulinaemia is primarily managed with antiviral therapy (for HCV/HBV-associated disease) and immunosuppression rather than antibiotics. Antibiotic use should be targeted to documented secondary bacterial infections only and not used empirically for vasculitis symptoms.

⚠️

Infection Screening Before Immunosuppression: Prior to rituximab or high-dose corticosteroids, screen for active TB (QuantiFERON-TB Gold), HBV (HBsAg, anti-HBc), HIV, and strongyloides in at-risk patients. Administer all indicated live vaccines at least 4 weeks before rituximab.

Prophylaxis Guidance

PCP prophylaxis: Co-trimoxazole 960 mg 3×/week when prednisolone >20 mg/day for >4 weeks plus rituximab.
HBV reactivation: All HBcAb-positive patients receiving rituximab require entecavir prophylaxis for duration of therapy plus 12 months after cessation.
Antifungal prophylaxis: Consider fluconazole if prolonged high-dose corticosteroids in high-risk patients.
Vaccination: Annual influenza, pneumococcal (Prevenar 13 then Pneumovax 23), and zoster vaccine (Shingrix) before rituximab. COVID-19 boosters per ATAGI guidelines.

ACSQHC Standard 3 Alignment

Document indication and planned duration of immunosuppressive therapy at initiation. Review at each visit for dose reduction or cessation. Educate patients on infection risk, fever response plan, and when to seek urgent care. Ensure microbiology cultures taken before any empirical antibiotics for fever in immunosuppressed patients.

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