Preeclampsia and How It Hurts the Kidneys

High blood pressure during pregnancy could suggest preeclampsia

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Preeclampsia refers to development of high blood pressure in a pregnant woman, typically after 20 weeks of gestation in combination with other signs or symptoms of damage to other organs.  It is a very distinct clinical entity with a specific pathophysiology. The combination of preeclampsia with seizures in a pregnant woman is however called "eclampsia".

Before we go further though, I would like to reiterate that having some sort of organ damage is essential to differentiate preeclampsia from other entities associated with high blood pressure in pregnancy.

 A woman could have pre-existing high blood pressure even before she was pregnant that carries on into pregnancy, or she could develop new onset of high blood pressure without any end organ damage as well. These entities would not be the same as preeclampsia.

So why am I talking about problems of blood pressure in pregnant women on a kidney disease blog? Well, the reason is that the kidney is one of the most commonly affected organ in pregnant women with preeclampsia.


As mentioned above, the hallmark of preeclampsia is a new elevation in blood pressure.  However, the affected pregnant woman will typically have signs of damage to other organs.  

  • Edema  is common.  Swelling is a common feature in normal pregnancies anyway. Preeclampsia will make that worse
  • Signs of "end-organ dysfunction" (low platelet count, elevated serum creatinine, abnormal tests of liver function)

The above symptoms are what I call the "typical" signs/symptoms. Ones that are undoubtedly concerning, but not usually a cause for alarm.

However, if the preeclampsia worsens, it can progress in to what we call "severe eclampsia" which would require immediate intervention from physicians (the actual treatment is discussed in another article). Here are some characteristics of severe preeclampsia (again, not an all-inclusive list):

  • Change in mental status
  • Severe headache 
  • Visual disturbances 
  • Kidney failure
  • Bleeding due to low platelet counts
  • Fluid accumulation in the lungs, or pulmonary edema 


Preeclampsia is thought to develop due to a combination of immunological or genetic factors. Why it only affects some women and not others is still not fully understood, although we have identified certain risk factors. 

These factors through various mechanisms, most of which we are just beginning to understand, lead to abnormal placental structure and function.  One characteristic abnormality that is often seen is abnormal blood vessel development in the placenta.  This leads to deprivation of oxygen in the placenta and consequent production of factors that are harmful to the health of the maternal blood vessels.

These harmful factors make their way in to the maternal blood stream where they cause injury to a specific part of the maternal blood vessel called the endothelium which leads to the signs and symptoms of preeclampsia. Everything that we see in preeclampsia, ranging from headache and visual disturbances to kidney failure and protein loss in the urine can be traced back to this mechanism.

One of the harmful substances produced by the oxygen deprived placenta that is receiving a lot of attention lately is something called SFLT-1 (Soluble fms–like tyrosine kinase-1). Discovery of this factor as a key mediator of development of preeclampsia has opened new doors for treatment of this condition. 

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