Usefulness of lactate dehydrogenase in differentiating abnormal cervical lymphadenopathy

Cervical lymphadenopathy is commonly seen in general practice, and its etiology is diverse. Establishing the diagnostic strategy for lymphadenopathy would be desirable to avoid overlooking neoplasms or other critical conditions. This study aims to identify the useful laboratory parameters for cervical lymphadenopathy that require clinical observation or intervention.

The participants were outpatients presenting cervical swelling or cervical lymph node (LN) pain who consulted the General Internal Medicine department from 2010 to 2016. We evaluated the characteristics, physical findings, and laboratory parameters with final diagnoses by multivariate logistic regression analysis. We categorized the final diagnoses as "Clinical Intervention Required Group (CIRG)" including necrotizing lymphadenitis, hematologic neoplasms, metastatic lymphadenopathy, tuberculous lymphadenitis, bacterial infectious diseases, infectious mononucleosis, autoimmune diseases, and other abnormal conditions or "No-CIRG" not requiring further clinical observation or intervention.

We evaluated 409 participants, with 130 (31.8%) diagnosed as belonging to the CIRG. There was an association between CIRG and various parameters: age ≥60 years old (adjusted odds ratio [AOR], 2.70; 95% confidence interval [CI], 1.48-4.90), having a referral (AOR, 1.83; 95% CI, 1.12-3.00), diameter of LN ≥ 2 cm (AOR, 1.91; 95% CI, 1.05-3.48), fixed LNs (AOR, 2.74; 95% CI, 1.02-7.37), and lactate dehydrogenase (LD) ≥400 U/L (AOR, 3.78; 95% CI, 1.46-9.77). Eighty-two percent of LD ≥ 400 cases in the CIRG were infectious mononucleosis or necrotizing lymphadenitis.

Besides the clinical indicators reported previously, we may apply an elevated LD level as a useful indicator of cervical lymphadenopathy that requires further clinical observation or intervention.