Evaluation of Total Serum Calcium Levels Across Gestational Trimesters Compared to Non-Pregnant Controls in Wadi Al-Shati, Libya: A Comparative Clinical Biochemical Study
DOI:
https://doi.org/10.65405/nt07bb55Keywords:
Serum Calcium, Gestational Hypocalcemia, Pregnancy Trimesters, Clinical Biochemistry, CPC Method, Wadi Al-Shati, Academic PromotionAbstract
Background: Calcium is an essential divalent physiological cation governing fundamental biological processes, including neuromuscular transmission, muscular excitation-contraction coupling, blood coagulation enzyme complexes, and fetal osteogenesis. Maternal calcium homeostasis is subject to profound hemodynamic and endocrine adaptations during pregnancy.
Objectives: This clinical biochemistry study was conducted to quantitatively evaluate and compare total venous serum calcium concentrations (in mg/dL) across the first, second, and third trimesters of pregnancy against matched non-pregnant healthy controls, and to assess the epidemiological prevalence and clinical severity of gestational hypocalcemia in Wadi Al-Shati district, southwestern Libya.
Materials and Methods: A prospective case-control investigation was performed comprising 199 female participants (149 pregnant women: 50 in first trimester, 50 in second trimester, 49 in third trimester; and 50 age-matched non-pregnant healthy controls). Total venous serum calcium was measured spectrophotometrically using the standard o-cresolphthalein complexone (CPC) photometric method under standardized alkaline conditions (pH 10-12) at 575 nm. Normal laboratory reference boundaries were corrected to 8.5 - 10.5 mg/dL. Statistical analyses were executed via SPSS version 26.0, including independent Student's t-test, One-Way Analysis of Variance (ANOVA), Tukey's Honestly Significant Difference (HSD) post-hoc test, and Pearson's Chi-square (χ²) test of independence.
Results: Pregnant women exhibited a statistically significant overall decrease in mean serum total calcium compared with non-pregnant healthy controls (8.85 ± 1.11 mg/dL vs. 9.48 ± 0.53 mg/dL; t = 3.825, df = 197, p = 0.00018). Trimester-stratified concentrations were 9.04 ± 1.14 mg/dL in the first trimester (T1), dropping to a nadir of 8.69 ± 1.09 mg/dL in the second trimester (T2), and maintaining 8.82 ± 1.09 mg/dL in the third trimester (T3). One-Way ANOVA verified significant variance among the four study cohorts (F = 5.959, p = 0.00066), with Tukey's HSD post-hoc test demonstrating significant decrements between controls and both second (p = 0.0006) and third (p = 0.0069) trimesters. Gestational hypocalcemia (< 8.5 mg/dL) was present in 38.9% of all pregnant women (34.0% in T1, 42.0% in T2, and 40.8% in T3), whereas 100% of controls were eucalcemic (χ² = 37.18, df = 6, p < 0.0001).
Conclusion and Recommendations: Maternal circulating total serum calcium declines significantly during gestation, reaching its lowest levels during the second and third trimesters due to physiological hemodilution, hypoalbuminemia, and rapid fetoplacental bone mineralization. Integrating routine serum calcium and albumin profiling into standardized antenatal panels across health centers in southern Libya and implementing targeted nutritional supplementation are urgently recommended.
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