Serum heat-stable alkaline phosphatase activity in normal pregnancy.

Objective: To determine the reference values for heat-stable alkaline phosphatase in apparently healthy non-pregnant and in normal pregnant females and to assess the suitability of this parameter as a measure of placental function and indirectly as a measure of foetal survival.

Design: A prospective study.

Setting: Ante-natal clinic, University of Nigeria Teaching Hospital, Enugu, Nigeria.

Participants: Ninety eight apparently normal pregnant females in various gestational ages and 47 apparently healthy non-pregnant females.

Main Outcome Measures: The serum heat-stable alkaline phosphatase activity.

Results: Variability in values exists between individuals in the same gestational age. The mean and standard deviation of serum heat-stable alkaline phosphatase was found to be 0.79 +/- 1.54 iu/L in the control group. No significant difference was found (p < 0.05) between this and the mean and standard deviation of serum alkaline phosphatase of 0.98 +/- 1.28 iu/L found in the first eight weeks of gestation. However the means and standard deviations of first trimester, second and third trimester were significantly higher than the controls.

Conclusion: In the face of worsening economic situation in third world countries this simple method could be used in urban and some rural hospitals in assessing placenta insufficiency.