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Salivary Magnesium as a Non-Invasive Biomarker in Kidney Transplant Recipients Receiving Tacrolimus: A Cross-Sectional Study of Serum-Saliva Correlation
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R Ghanavati1   , MJ Saeedi -Borujeni2 , T Mohammadi Farsani3 |
1- Student Research Committee, Isf.C., Islamic Azad University, Isfahan, Iran
2- Community health research center, Isf.C., Islamic Azad University, Isfahan, Iran
3- Department of Medical Biotechnology, Isf.C., Islamic Azad University, Isfahan, Iran , Taiebeh.mohammadi@iau.ac.ir |
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Abstract: (1337 Views) |
Background & aim: Tacrolimus is the cornerstone immunosuppressant in kidney transplantation but is associated with renal magnesium wasting, predisposing recipients to hypomagnesemia with significant clinical implications. While serum magnesium monitoring is the standard of care, it is invasive and resource-intensive. Saliva, as a non-invasive biofluid, holds promise as a surrogate biomarker. This study aimed to evaluate the correlation between salivary and serum magnesium concentrations in kidney transplant recipients receiving tacrolimus across different post-transplant intervals.
Methods: In this cross-sectional study, 100 adult kidney transplant recipients on tacrolimus maintenance therapy were enrolled. Blood and unstimulated saliva samples were collected at four predefined time points: 1 week, 1 month, 3 months, and 6 months post-transplant. Saliva samples (5 mL) were centrifuged at 3000 rpm for 10 minutes and stored at 4°C. Serum and salivary magnesium concentrations were quantified using a standardized colorimetric spectrophotometric assay (λ = 532 nm; Pars Azmoon kit). The collected data were analyzed using independent t-tests, analysis of variance, and Pearson correlation coefficient.
Results: The incidence of hypomagnesemia peaked at 52% during the third month post-transplant. Mean serum magnesium levels declined from 2.03 mg/dL at week 1 to 1.84 mg/dL at month 3. Similarly, salivary magnesium decreased from 0.145 mmol/L to 0.108 mmol/L over the same period. A statistically significant correlation between serum and salivary magnesium was observed only at week 1 (r = 0.392, p = 0.008). Receiver operating characteristic (ROC) curve analysis indicated acceptable diagnostic accuracy for salivary magnesium in detecting hypomagnesemia exclusively at this early time point (AUC = 0.781, p = 0.006). No significant gender-based differences in magnesium levels were observed. In later phases (months 1, 3, and 6), the correlation weakened, and diagnostic performance diminished.
Conclusion: Salivary magnesium shows potential as a non-invasive surrogate for serum magnesium monitoring exclusively in the early post-transplant period (week 1). However, the correlation weakens significantly in later phases, limiting its utility for long-term monitoring. Further studies with larger cohorts, rigorous control of confounding factors (e.g., calcineurin inhibitor levels, dietary intake), and validation of additional salivary biomarkers are warranted to establish its clinical reliability.
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| Keywords: Tacrolimus, Kidney Transplantation, Salivary Magnesium, Hypomagnesemia, Biomarker, Non-invasive Monitoring. |
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Type of Study: Applicable |
Subject:
Dentistry
Received: 2025/07/30 | Accepted: 2025/12/23 | Published: 2025/12/24
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