A woman who may have signs of early or mild
preeclampsia will have her blood tested to detect
additional signs of preeclampsia. A woman who has preeclampsia may have
specific blood tests to help assess her health.
Uric acid. Increased uric acid in the blood is
often the earliest laboratory finding related to preeclampsia. Uric acid is a
waste product formed from the breakdown of some protein-rich foods and the
breakdown of cells in the body. It is normally filtered from the blood by the
kidneys. But if the kidneys have been damaged by preeclampsia, uric acid
levels in the blood may rise.
Hematocrit. A high hematocrit value can be a sign of
preeclampsia. Hematocrit tells the percentage of red blood cells in the blood-a
hematocrit value of 42 means that red blood cells make up 42% of the blood
volume. A normal hematocrit value for a nonpregnant woman is between 36% and
44%. During pregnancy, the hematocrit value normally decreases-the fluid in the
blood (plasma) increases, making red blood cells less concentrated. But
preeclampsia often causes the body's tissues to absorb blood plasma. The blood
becomes more concentrated, resulting in an abnormally high hematocrit value.
Platelets. The number of
platelets in the blood may be measured. Preeclampsia
may cause an abnormally low platelet count.
Partial thromboplastin time (PTT). This is a measure
of the time it takes blood to clot. Preeclampsia can cause problems with blood
clotting that increase the partial thromboplastin time.
Electrolytes. Examples of important electrolytes
include sodium, potassium, magnesium, calcium, and chloride. The amounts of
electrolytes in the body may change if preeclampsia is causing kidney damage or
is causing fluid to leak out of blood vessels into surrounding tissues
Kidney function tests. These tests check the amount
of certain substances found in the blood that are normally removed from the
body by the kidneys. These substances, which include blood urea nitrogen and
creatinine, increase in the blood if the kidneys have been damaged. (For more
information, see the topic Creatinine and Creatinine
Liver function tests. These tests monitor enzymes
that indicate how well the liver is working.