What are the laboratory findings in DRESS (Drug Reaction with Eosinophilia and Systemic Symptoms) syndrome?

From the Guidelines

DRESS syndrome laboratory evaluation should include a complete blood count with differential, comprehensive metabolic panel, urinalysis, and inflammatory markers, as recommended by the most recent guidelines 1. When evaluating a patient with suspected DRESS syndrome, it is essential to consider the following laboratory tests:

• Complete blood count (CBC) with differential to assess for leukocytosis, eosinophilia, and atypical lymphocytosis
• Comprehensive metabolic panel to evaluate liver and kidney function
• Urinalysis to assess for nephritis or other renal involvement
• Inflammatory markers, such as C-reactive protein and erythrocyte sedimentation rate, to assess the severity of the reaction Additional tests may be necessary based on the patient's clinical presentation, such as:
• Creatine kinase to assess for muscle involvement
• Coagulation studies to evaluate for bleeding disorders
• Blood cultures to rule out infectious causes
• Specific organ-targeted tests, such as chest X-ray for pulmonary involvement or cardiac enzymes for myocarditis
• Viral studies, including HHV-6, HHV-7, EBV, and CMV, as viral reactivation is common in DRESS syndrome These laboratory tests help confirm the diagnosis, assess the severity of the reaction, and guide management decisions for this potentially life-threatening condition 1. It is crucial to note that the management of DRESS syndrome involves a comprehensive approach, including the withdrawal of the offending drug, supportive care, and close monitoring of the patient's condition 1. In terms of specific laboratory findings, the CBC typically shows leukocytosis with marked eosinophilia (>500 cells/μL or >10% of white blood cells) and possible atypical lymphocytosis 1. Liver function tests often reveal elevated transaminases (AST, ALT), alkaline phosphatase, and bilirubin, indicating liver involvement 1. Renal function tests may show elevated creatinine and BUN if kidney involvement is present 1. The most recent guidelines recommend a thorough evaluation, including a biologic checkup, to assess for associated nephritis and other possible etiologies 1.

From the Research

DRESS Syndrome Laboratory Findings

• Laboratory results for DRESS syndrome typically reveal leukocytosis, atypical lymphocytes, eosinophilia, and alterations of liver and kidney function tests 2.
• Eosinophilia is a key laboratory finding in DRESS syndrome, with an eosinophil count above 6000 × 10^3/μL indicating a poor prognosis 2.
• Other laboratory abnormalities may include thrombocytopenia, pancytopenia, leukocytosis, and coagulopathy, which are associated with a poor prognosis 2.

Organ Involvement in DRESS Syndrome

• The kidneys are the second most affected organ in DRESS syndrome, with renal involvement ranging from acute kidney injury to chronic renal disease 3.
• Liver involvement is also common in DRESS syndrome, with fulminant hepatitis and liver necrosis being major causes of mortality 2.
• Other organs that may be involved in DRESS syndrome include the lungs, pancreas, and heart 4, 5.

Diagnostic Criteria for DRESS Syndrome

• The RegiSCAR scoring system is commonly used to diagnose DRESS syndrome, with a score system based on clinical and laboratory findings 4, 2, 6.
• A skin biopsy and patch testing may also be helpful in the diagnostic process 2.
• A thorough clinical history, including all suspected medications, is essential for identifying the culprit drug and establishing a diagnosis of DRESS syndrome 2.