Of all the laboratory tests performed on pregnant women, monitoring the level of albumin (protein found in the urine) is arguably one of the most important. Indeed, it makes it possible to detect a serious complication of pregnancy: preeclampsia. We take stock with Professor Cyril Huissoud, secretary general of the CNGOF, head of the Obstetric Gynecology Service of Croix-Rousse.
What is albuminuria?
During pregnancy, the pregnant woman is required to perform monthly examinations, including laboratory biological tests. One of them is to measure the level of albumin in the urine, or in other words protein. This is because proteins pass into the blood, and it is the filtered blood that makes up the urine. " A small part of the protein passes in the urine. Normally, it should not exceed 150 mg per 24 hours. But during pregnancy, we accept an albuminuria of 300 mg per 24 hours (or 0.3 g), but no more », Explains Professor Huissoud. Beyond this quantity, the doctor therefore considers that the kidneys filter poorly the proteins which are found in too large a quantity in the urine. This occurs in 3 to 4% of pregnancies.
How to screen for albuminuria?
Each month, a dosage is performed, most often in the laboratory through a urine analysis (first visit to the toilet in the morning). A drop of urine is taken to measure the concentration of albumin. This is a screening test. A test done with a dipstick is also possible at home, but it will be less precise. When a cross appears, you should go to the laboratory to check. If the rate is indeed higher than the normal thresholds, the doctor will ask for a test over 24 hours which will make it possible to make the diagnosis. " It often happens that the screening tests are false positive, which is why the 24-hour laboratory test is the most important », Says the specialist.
How to interpret the results?
If the result of the albuminuria test is positive in early pregnancy, there is a high risk that the causes are pre-existing to the pregnancy. " On the other hand, after 20 weeks of amenorrhea, a pathology related to the pregnancy is suspected. This is why it is important to have referrals early in pregnancy », Observes Professor Huissoud.
Preeclampsia, the main risk
If the sample is positive and the mother-to-be did not have a weak renal filter before the pregnancy, the doctor will suspect preeclampsia (formerly called toxemia of pregnancy). This is characterized by significant proteinuria and arterial hypertension beyond the 5th month of pregnancy. But the difficulty is that not all of the symptoms appear simultaneously. Preeclampsia occurs in 1 to 3% of pregnancies, with a higher rate in first-time mothers. " It is a potentially serious pathology because it is one of the leading causes of maternal and fetal mortality and morbidity in France. This is a real public health problem », Warns the obstetrician-gynecologist.
Note that if the hypertension is not found directly, the doctor may tend to have nephropathy of pregnancy, but this pathology is rarer.
What are the risks for mom and baby?
Preeclampsia puts both the mother and baby at risk. This is because the fetus may suffer from intrauterine growth retardation due to an abnormality in the formation of the blood vessels in the placenta, the organ allowing exchanges between the mother and the fetus. Often the baby is born prematurely in order to protect the mother. In very rare cases (percentage?), The baby may die in utero.
For the mother, the disease can spread to the mother's body. First in the kidneys, which can lead to high blood pressure. " Note that hypertension can come before or after the increase in the level of albumin in the urine », Observes the doctor. Ultimately, it is the mother's brain that can become the site of edema associated with hypertension and proteinuria. " A pregnant woman may suffer from potentially serious seizures (eclampsia). In France, 1,200 women are affected by eclampsia each year », Reports Professor Huissoud.
Depending on the albumin level: several degrees of severity
Depending on the level of protein found in the urine, the pathology will be considered more or less severe.
Proteinuria greater than 3g per 24 hours is considered severe, but not necessarily serious. " If we are early in the pregnancy, we will try to save time for the baby. This means that the preeclampsia is not bad enough to decide to deliver the baby right away. », Continues the specialist.
In contrast, the occurrence of HELLP syndrome is an imminent sign of clinical worsening. It results in the destruction of the constituent cells of the liver. This can then lead to bleeding disorders with in very rare cases liver bleeding, requiring a transplant.
The other signs of severity are strong headaches, abdominal pain, eye problems … They can be the warning sign of a seizure attack: it is eclampsia.
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What treatment for high albuminuria?
" Unfortunately, there is no treatment to control proteinuria, other than the birth of the baby since it is a malfunction of the placenta that is involved », Says Professor Huissoud. However, the obstetrician-gynecologist may prescribe anti-hypertensive treatment in order to limit the risks of neurological complications in the mother. Monitoring of the mother will be strengthened, either in hospital or on an outpatient basis, with more ultrasounds to monitor the baby's growth. An injection of corticosteroids may also be decided in order to accelerate the maturation of the fetus and limit the risks for the baby in the event of a premature birth. Moreover, " the mother must remain at rest and avoid the stresses of everyday life. She will be able to walk and do her shopping, but will certainly be stopped if she is working », Continues the doctor.
In the context of a future pregnancy, the mother may be advised to take aspirin at an anti-pleasing dose to halve the risk of developing preeclampsia again.
From a dietary point of view, it is not advisable to adopt a salt-free diet because it is necessary to ensure a good perfusion of the uterus with good blood pressure. However, it should not be abused in order to limit hypertension either. Alcohol, already contraindicated during pregnancy, should also be avoided completely.