Every patient with hair loss needs blood tests. Surprisingly, some blood tests reveal more information than you might imagine!
For example- a complete blood count (CBC) provides counts of red cells, white cells, and platelets and we can tell if a patient has various issues – like anemia.
But there are some interesting information that might also be hidden in test results. Let’s talk about inflammatory indices such as the neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR). Higher values generally reflect a shift toward systemic inflammation. The exact cutoffs and significance is still being studied by researchers but NLR ratios above 3 seems to be concerning and PLR ratios that rise for a given patient over time may also be concerning (although exact cutoff values are less clear)
In alopecia areata (AA), several case-control and cross-sectional studies report higher NLR and PLR in patients vs controls. More interestingly, some studies show stepwise increases with disease burden—patients with extensive disease (e.g., higher SALT scores, alopecia totalis/universalis) tend to have higher NLR and PLR than those with patchy AA. A few reports also link higher baseline NLR with longer disease duration and greater activity (e.g., positive hair-pull test), suggesting these ratios may reflect ongoing immune activation.
There are also early signals on prognosis and treatment response. Small cohorts have found that lower baseline NLR may be associated with better response to therapies (including corticosteroids and JAK inhibitors), whereas persistently elevated NLR & PLR can track with refractory disease. However, these findings are inconsistent across studies and often lose significance after adjusting for confounders.
Importantly, evidence comes almost entirely from small, observational studies with variable cutoffs and methods. There are no validated thresholds and no randomized trials confirming clinical utility. For now, NLR and PLR are best viewed as adjunctive, research-level markers—useful for understanding systemic inflammation in AA, but not reliable standalone tools for diagnosing, staging, or guiding treatment decisions.
