# Association Between Serum Fluoride and Urine Fluoride Levels and Hemoglobin Levels in Pregnant Women: A Cross-Sectional Study in Rural Telangana, India

## TL;DR

This study explores the relationship between fluoride levels in blood and urine and hemoglobin levels in pregnant women in rural India.

## Contribution

The study introduces the urine-to-serum fluoride ratio as a potential biomarker for systemic fluoride burden in pregnant women.

## Key findings

- The urine-to-serum fluoride ratio was significantly higher in high-fluoride villages compared to low-fluoride villages.
- Non-anemic pregnant women had significantly higher hemoglobin levels compared to anemic individuals.
- Fluoride distribution and excretion patterns may influence hemoglobin levels more than total systemic fluoride concentration.

## Abstract

Background

Anemia affects a substantial proportion of the global population, with pregnant women being particularly vulnerable. In regions with high fluoride levels in drinking water, fluoride exposure is known to impair nutrient absorption, potentially exacerbating anemia.

Objective

This study aimed to assess the correlation between serum and urinary fluoride levels and hemoglobin concentration in pregnant women, while controlling for other known causes of anemia.

Methods

A cross-sectional observational study was conducted on 98 pregnant women (gestational age <12 weeks) from high-fluoride villages (fluoride >4 ppm) and low-fluoride villages (fluoride ≤1.5 ppm) in the Yadadri Bhuvanagiri District of Telangana, India. Serum and urine fluoride levels were measured using an ion-selective electrode, and hemoglobin was analyzed using a three-part hematology analyzer. Statistical analyses included Pearson’s correlation, multivariate linear regression, and principal component analysis.

Results

Mean hemoglobin levels were slightly lower in the high-fluoride group (HFG: 11.80 ± 1.46 g/dL) than in the low-fluoride group (LFG: 11.98 ± 1.46 g/dL), with a higher prevalence of anemia in the HFG (24.48%) compared to the LFG (14.28%), though these differences were not statistically significant. Urine fluoride levels were higher in the HFG (1.28 ± 0.81 ppm) than in the LFG (1.09 ± 0.89 ppm; p > 0.05), while serum fluoride levels were marginally lower in the HFG (0.37 ± 0.24 ppm) compared to the LFG (0.41 ± 0.25 ppm; p > 0.05). The urine-to-serum fluoride ratio was significantly higher in the HFG (4.42 ± 3.47) than in the LFG (2.36 ± 1.40; p < 0.001). Non-anemic individuals had significantly higher hemoglobin levels (β = 2.51 g/dL, 95% CI: 1.96-3.07; p < 0.001).

Conclusion

Our findings suggest that the pattern of fluoride distribution and excretion, rather than total systemic fluoride concentration, may play a more critical role in influencing hemoglobin levels. The urine-to-serum fluoride ratio may serve as a reliable biomarker for estimating systemic fluoride burden and may be useful in monitoring fluoride exposure in vulnerable populations.