Diagnostic Accuracy of Salivary Ferritin as a Non-Invasive Biomarker for Iron Deficiency Anaemia: A Comparative Cross-Sectional Study

Abstract

Background: Iron deficiency anaemia (IDA) is the most common micronutrient deficiency globally, particularly affecting populations in low- and middle-income countries. While serum ferritin is the conventional diagnostic marker, its invasive nature and limitations in inflammatory states necessitate alternative non-invasive tools. Salivary ferritin has emerged as a potential biomarker, yet its diagnostic performance remains underexplored.

Objective:

To evaluate the diagnostic accuracy of salivary ferritin for identifying IDA, using serum ferritin as the reference standard.

Methods: This comparative cross-sectional diagnostic accuracy study included 160 participants (80 IDA patients and 80 age- and sex-matched healthy controls) recruited from a tertiary care hospital. Haemoglobin and serum ferritin levels were measured via venous blood, while salivary ferritin was quantified using ELISA from unstimulated whole saliva. Correlation analysis, group comparisons, and ROC curve analysis were performed to assess diagnostic validity.

Results: Salivary ferritin levels were significantly lower in IDA patients (mean ± SD: 3.82 ± 1.48 ng/mL) compared to controls (15.93 ± 3.03 ng/mL, p < 0.001). A diagnostic cut-off of <8 ng/mL yielded 100% sensitivity and specificity within the study sample. Correlation between serum and salivary ferritin was weak (r = –0.175 in IDA group), limiting its quantitative predictability. Frequency analysis confirmed that 79/80 IDA patients had salivary ferritin <10 ng/mL, while all but one control exceeded this threshold.

Conclusion: Salivary ferritin demonstrates high diagnostic accuracy and may serve as a viable, non-invasive screening tool for IDA. Its integration into point-of-care devices could improve early detection, especially in resource-limited settings and vulnerable populations. Further validation in larger, diverse cohorts is warranted.