GRN and periodontitis: <h4>Background</h4>The aim of this study was to study the effect of non-surgical periodontal therapy (NSPT) on gingival crevicular fluid (GCF) and serum progranulin (PGRN) levels in the early healing phases.<h4>Methods</h4>The study included periodontitis (test) (n = 24) and periodontal health (control) (n = 24) groups.