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Thyroxine and fetal blood coagulation: a fetal lamb study
C T Kisker1, D Bohlken, W R Clarke
1Department of Pediatrics, University of Iowa College of Medicine, Iowa City 52242.
Journal of Developmental Physiology
|February 1, 1993
Summary
High levels of triiodothyronine (T3) in fetal lambs during the last trimester of pregnancy altered blood coagulation factors. Specifically, T3 significantly decreased Factor V and increased Factor XII activity.
Area of Science:
- Perinatology
- Endocrinology
- Hematology
Background:
- Glucocorticoids are known to accelerate fetal lamb blood coagulation development.
- The role of thyroid hormones, specifically triiodothyronine (T3), in fetal hemostasis remains less understood.
Purpose of the Study:
- To investigate the influence of high levels of triiodothyronine (T3) on the development of blood coagulation in fetal lambs during the third trimester of gestation.
Main Methods:
- Eight twin fetal lambs were studied in the last trimester of pregnancy.
- One twin fetus received intravenous T3 infusion, while the control twin received a dextrose infusion.
- Blood samples were collected to measure prothrombin time (PT), partial thromboplastin time (PTT), thrombin time (TT), fibrinogen, and coagulation factors II, V, VII, VIII, IX, X, XI, and XII.
Main Results:
- Factor V activity significantly decreased in T3-infused lambs compared to controls (P = 0.038).
- Factor XII activity significantly increased in T3-infused lambs (P = 0.004).
- Factor VII showed a trend towards decrease but did not reach statistical significance (P = 0.06).
Conclusions:
- High levels of T3 during the third trimester of fetal lamb development are associated with alterations in blood coagulation.
- Specifically, elevated T3 levels lead to a moderate decrease in Factor V and an increase in Factor XII activity.