Simple lithium measurement in capillary dried plasma microsamples collected with the HealthID PSD device

Monitoring serum lithium concentrations is essential during bipolar disorder treatment. This study aimed to develop and validate a simple approach for estimating serum lithium concentrations using dried plasma spots (DPS) obtained from the HealthID PSD device after application of capillary blood.

A clinical comparison study was performed using paired serum samples and DPS from 40 patients undergoing lithium therapy. Linearity was demonstrated from 0.1–2.5 mmol/L. Extraction yields were 93.2–95.7 %, and chloride correction significantly improved imprecision. Hematocrit (30–50 %) and applied volume (160–240 µL) showed minimal influence on corrected concentrations. Lithium remained stable for 21 days.

Lithium can be reliably quantified in DPS generated with the HealthID PSD device using a routine colorimetric assay.