Serum Calcium, Phosphorous and Alkaline Phosphatase levels in Different Trimesters of pregnancy

Document Type : Original Article


1 Associate Professor of Orthopaedics, Mashhad University of Medical Siences

2 Assistant Professor of Obstetrics and Gyneocology, Mashhad University of Medical Siences

3 Assistant Professor of Orthopaedics, Mashhad University of Medical Siences

4 Orthopaedist


Introduction:Fetus skeleton is formed during pregnancy and calcium and phosphorous for
this mineralization is provided by mother, so significant changes may occur in the mother’s
skeleton. This study was conducted to evaluate the changes of serum and urinary markers of
ossification and bone absorption during pregnancy.
Material and Methods: In this cross-sectional study, from Oct. 2005 to Jul. 2006, 307
pregnant women, at Imam Reza Hospital in Mashhad, were randomly assessed. Serum
calcium, phosphorous, ALP, 24 hours urinary excretion of calcium and phosphorus were
determined. Data were analyzed by SPSS 9.5 software, ANOVA and Tukey HSD tests.
Results: ANOVA test indicated that, there was no significant difference between dependent
variables (calcium, phosphorous, alkaline phosphatase), 24 hours urinary excretion of
calcium, phosphorous and the age of mother (P=0.057), but there was meaningful
relationship between serum ALP level, 24 hours urinary excretion of phosphorous and
different trimesters of pregnancy (P=0.007). Serum ALP level in the third trimester was
varied, compared to the first and second trimesters. However there was no difference in
these amounts in the first and the second trimesters.
Conclusion: There was no significant alteration in the mean ratio of serum calcium,
phosphorus level and 24 hours urinary excretion of calcium in different trimesters of
pregnancy (P= 0.070). Noticeable correlation observed between mean serum ALP, 24 hours
urinary excretion of phosphorous and different trimesters of pregnancy (P= 0.007, P= 0.025
respectively). Also, differences in the mean serum calcium level, 24 hours urinary excretion
of phosphorous in multiparous and nulliparous patients was very clear.


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