Clinical utility of peripheral blood laboratory testing in the diagnostic workup of prurigo nodularis: A multicenter cohort study

BACKGROUND: Prurigo nodularis (PN) is a chronic inflammatory skin disease associated with several systemic comorbidities. However, there is lack of evidence supporting specific laboratory testing in the diagnostic workup of PN patients. OBJECTIVE: To characterize the frequency and severity of clinical laboratory abnormalities in PN patients compared to controls. METHODS: Cross-sectional study of adult patients between October, 2015 and August, 2021 using TriNetX, a global health records database encompassing over 74 million patients. RESULTS: A total of 12,157 PN patients were matched to 12,157 controls. Significantly, greater proportions of PN patients had moderate-to-severely decreased hemoglobin, elevated transaminases, decreased albumin, increased bilirubin, increased serum creatinine, decreased estimated glomerular filtration rate, higher hemoglobin A1c levels, and alterations in thyroid stimulating hormone. LIMITATIONS: Our data identifies associated laboratory abnormalities in PN patients but is unable to support a causal relationship. CONCLUSION: PN patients are more likely to have laboratory abnormalities on renal, hepatic, hematologic, endocrine, and metabolic laboratory testing, demonstrating a role for systemic testing in the diagnostic workup of PN patients.