What is Protein S?
Protein S is a type of protein closely associated with vitamin K and clotting. The protein, or specifically glycoprotein, works hand-in-hand with Protein C. If a patient has experienced deep vein thrombosis or thromboembolism, tests are ordered to measure the percentages of Protein S and Protein C, along with other relevant blood elements. The tests need to be run within the first 10 days after the clotting event has taken place. There are three types of Protein S deficiency:

  • Type I is associated with decreased free, functional and total Protein S.
  • Type II is associated with decreased functional, but normal free and total Protein S.
  • Type III is associated with decreased functional and free, but normal total Protein S.

Normal Value Range

  • Negative Pregnancy Adult: 70 to 140 percent
  • Pregnancy Trimester One: 39 to 105 percent
  • Pregnancy Trimester Two: 27 to 101 percent
  • Pregnancy Trimester Three: 33 to 101 percent

While high levels of Protein S are not typically associated with a medical condition or concern, low levels can be life-threatening. Too little Protein S can lead to abnormal clotting activity that can lead to vein blockage and/or decreased blood flow.

< Laboratory Values During Pregnancy

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