Cold Agglutinin Disease (CAD)

Hemolytic anemia and cold-induced symptoms are 2 hallmarks of cold agglutinin disease (CAD). Other diseases that may have similar presentations are discussed below.  

Differential Diagnosis for Hemolytic Anemia

Warm autoimmune hemolytic anemia (wAIHA) and 2 additional conditions associated with hemolytic anemia should be considered as part of the differential diagnosis for CAD.

  • wAIHA. Two entities should be considered:
  • Drug-induced hemolytic anemia 
  • Evans syndrome
  • Paroxysmal cold hemoglobinuria
  • Hemolytic transfusion reaction

wAIHA is the most common type of immune-mediated hemolytic anemia, accounting for 70% to 80% of adult cases and 50% of pediatric cases. It is mediated by warm autoantibodies, usually immunoglobulin G (IgG), which bind to erythrocytes at an ideal temperature of 37°C.1 Evans syndrome is a rare type of wAIHA characterized by autoimmune hemolytic anemia, immune thrombocytopenic purpura, and a positive direct anti-human globulin test (DAT) result.2,3  The 2 main factors distinguishing between CAD and wAIHA are (1) anticipated worsening of symptoms on exposure to cold in CAD but not in wAIHA and (2) direct antiglibulin (DAT) result for anti-C3 subtypes in CAD vs IgG and/or anti-C3 subtypes in wAIHA.1,4 

The 2 main mechanisms by which drugs can induce hemolytic anemia are immune-mediated destruction and oxidative damage of erythrocytes. One study reports that the drugs most commonly implicated in immune hemolysis are diclofenac, piperacillin, ceftriaxone, and oxaliplatin.5 However, other studies report that antibiotics in the cephalosporin and macrolide families and fludarabine are the drugs responsible for most cases of drug-induced immune hemolysis.6-8 Drugs that cause hemolysis via oxidative damage include primaquine, dapsone, and phenazopyridine.8 Patients with glucose-6-phosphate dehydrogenase deficiency are highly susceptible to hemolysis with these agents.9    

In differentiating between CAD and drug-induced hemolysis, the patient history is important. The recent use of a new medication or modification of a medication would be noted in drug-induced hemolysis. Additionally, a positive DAT result for IgG is seen in drug-induced hemolytic anemia, whereas in CAD, the result is positive for anti-C3 and is exacerbated after exposure to cold.2 

Differential Diagnosis for Cold-induced Symptoms

Secondary Raynaud phenomenon (RP) is associated with a list of conditions, usually autoimmune in origin. Some of the conditions most commonly associated with secondary RP are the following:

  • Systemic sclerosis
  • Systemic lupus erythematosus 
  • Mixed connective tissue disease 
  • Sjögren syndrome 
  • Dermatomyositis
  • Polymyositis 
  • Inflammatory bowel disease

Systemic lupus erythematosus is associated with some form of AIHA in 3% to 14% of cases, and the prevalence is higher in infants than in adult patients. AIHA also develops in patients with Sjögren syndrome in 2.8% of cases, and in most cases, the DAT result is negative. Rarely, AIHA develops in patients with inflammatory bowel disease, particularly ulcerative colitis. It is reasonable to order an autoimmune panel for patients with CAD who have arthritis, arthralgias, malar rash, muscle weakness, or other symptoms compatible with an autoimmune disorder.2 

Additional entities in the differential diagnosis for CAD are cryoglobulinemia and cold paroxysmal hemoglobinuria (CPH). 

Cryoglobulinemia is classified into type I and type II/III (mixed cryoglobulinemia) and manifests similarly to CAD. Cryoglobulins are IgG proteins that precipitate in serum at temperatures below 37°C and cause vaso-occlusion. Symptoms of type I cryoglobulinemia are livedo reticularis and digital ischemia, which may lead to ulceration and necrosis. Mixed cryoglobulinemia presents with palpable purpura and neurological signs. Arthralgias, fatigue, arthritis, and peripheral neuropathy are seen in both types. Cryoglobulinemia, unlike CAD, is not associated with hemolysis.10

CPH is a rare acquired AIHA characterized by complement-mediated intravascular hemolysis. In CPH, polyclonal IgG autoantibodies bind to the P antigen on erythrocytes in cold temperatures and mediate hemolysis through complement activation upon rewarming. CPH is typically seen in children younger than 5 years of age and manifests with hemoglobinuria (seen as dark urine), chills, rigors, cough, myalgias, nausea, jaundice, fatigue, anorexia, RP, urticaria, and headache. CPH typically follows a viral or bacterial infection. When present in adults, there is a strong association with tertiary syphilis. The Donath-Landsteiner reaction is specific for CPH; testing involves cooling a sample of the patient’s serum to 4°C (allows binding to P antigen) and rewarming to 37°C. After rewarming, complement-mediated hemolysis occurs.11


1. Kalfa TA. Warm antibody autoimmune hemolytic anemia. Hematology Am Soc Hematol Educ Program. 2016;2016(1):690-697. doi:10.1182/asheducation-2016.1.690

2. Jäger U, Barcellini W, Broome CM, et al. Diagnosis and treatment of autoimmune hemolytic anemia in adults: recommendations from the First International Consensus Meeting. Blood Rev. 2020;41:100648. doi:10.1016/j.blre.2019.100648

3. Jaime-Pérez JC, Aguilar-Calderón PE, Salazar-Cavazos L, Gómez-Almaguer D. Evans syndrome: clinical perspectives, biological insights and treatment modalities. J Blood Med. 2018;9:171-184. doi:10.2147/JBM.S176144

4. Barcellini W, Giannotta J, Fattizzo B. Autoimmune hemolytic anemia in adults: primary risk factors and diagnostic procedures. Expert Rev Hematol. 2020;13(6):585-597. doi:10.1080/17474086.2020.1754791

5. Mayer B, Bartolmäs T, Yürek S, Salama A. Variability of findings in drug-induced immune haemolytic anaemia: experience over 20 years in a single centre. Transfus Med Hemother. 2015;42(5):333-339. doi:10.1159/000440673

6. Johnson ST, Fueger JT, Gottschall JL. One center’s experience: the serology and drugs associated with drug-induced immune hemolytic anemia–a new paradigm. Transfusion. 2007;47(4):697-702. doi:10.1111/j.1537-2995.2007.01173.x

7. Garratty G. Immune hemolytic anemia associated with drug therapy. Blood Rev. 2010;24(4-5):143-150. doi:10.1016/j.blre.2010.06.004

8. Salama A. Drug-induced immune hemolytic anemia. Expert Opin Drug Saf. 2009;8(1):73-79. doi:10.1517/14740330802577351

9. Beutler E. Glucose-6-phosphate dehydrogenase deficiency: a historical perspective. Blood. 2008;111(1):16-24. doi:10.1182/blood-2007-04-077412

10.    Bhandari J, Awais M, Aeddula NR. Cryoglobulinemia. StatPearls. Updated June 7, 2021. Accessed September 10, 2021.

11. Shanbhag S, Spivak J. Paroxysmal cold hemoglobinuria. Hematol Oncol Clin North Am. 2015;29(3):473-478. doi:10.1016/j.hoc.2015.01.004

Reviewed by Harshi Dhingra, MD, on 9/14/2021.