Low hCG and PAPP-A in a Patient with an Autoimmune Disorder
Tuesday, June 09, 2009
Kenneth F. Trofatter, Jr., MD, PhD
Hi! I just got my 1st trimester screening test results today, and would love you thoughts.
I will be 40 years old when I deliver. I was 12 weeks when I did the testing.
NT: 1.5
Nasal Bone present
Free b - HCG: 0.29 MoM
Papp A - 0.34 MoM
Down syndrome risk: 1:1600
Trisomy 18 & 13: 1:50 (normal for my age 1:150)
I have an autoimmune condition, polymyositis that is under control. I am taking 12.5mg prednisone 1xday. I am ANA and Jo-1 positive.
Can you please help me understand these results? I am trying to look at the fact that it is only a 2% chance of the trisomy abnormalities, but it is difficult.
Are there any other reasons that my blood levels would be so low for both? Is there anything I should be precautionary about through the rest of my pregnancy because of this?
Thanks,
WJD
The combination of the low hCG and the low PAPP-A is typically a pattern seen in pregnancies complicated by trisomies 18 and 13 (in contrast to an elevated hCG coupled with a low PAPP-A in Down syndrome – trisomy 21). Both hCG and PAPP-A are produced by the trophoblasts of the placenta and low values could be the result of either a small placental mass or decreased production because of metabolic dysfunction. Both of these factors might be at work in trisomies 18 and 13.
However, in your case, there is also the possibility that your baby is chromosomally normal but has an abnormality of placentation that resulted from your autoimmune disorder. The immune system probably plays a very important role in normal placentation and the presence of certain autoantibodies (e.g., antiphospholipid antibodies, lupus anticoagulants, and anti-beta-2-glycoprotein-1) are thought to be associated with increased risk for abnormalities of placentation resulting from abnormal trophoblast migration and invasion of the maternal spiral arterioles. Indeed, if you have not been screened for these specific autoantibodies, I would recommend that you have that done. Such pregnancies are at increased risk for poor fetal growth (intrauterine growth restriction), fetal loss, pregnancy-induced hypertensive disorders, and early delivery. If you have any of these other autoantibodies, you might also be at increased risk for thromboembolic complications as well.
Whenever we find a pregnancy that has low hCG and PAPP-A levels and a chromosomally normal baby, it is recommended that fetal growth be followed at serial intervals, Doppler flow studies (e.g., umbilical, uterine , and fetal middle cerebral arteries) be done to evaluate impaired placental perfusion from either the fetal or maternal side and evidence of fetal blood flow redistribution (preservation of the brain at the expense of perfusion of ‘nonessential’ organs because of reduced placental transfer), and both mother and baby be monitored carefully for evidence of compromise. Your doctors can give you specific details of what should be done with regard to the latter.
Best of luck to you and please let us know how things turn out.
Dr T
Labels: first trimester screening, hCG, PAPP-A
2 Comments:
At Fri Sep 18, 05:56:00 PM 2009,
Anonymous said…
Hi Dr. T,
Wanted to give you an update, I am the WVD, I have controlled polymyositis, on 12.5mg of Prednisone for the entire pregnancy. My CPK levels have stayed in the normal range. I had low values for both HCG and PAPP-A in the 1st Trimester Screen.
Until now, I have had a very uneventful pregnancy, and have considered myself very blessed!
We chose not to do amnio, but did have ultrasound, at 19 weeks, which confirmed that there were no "markers" visible for the Trisomy chromosome.
At 24 weeks, I began what was to be a monthly ultrasound to keep an eye on the growth of the baby. All was well, and the baby measured in the 59th percentile, weighing in at 1lb10oz.
I just went back at 28 weeks, and they noticed a placental abnormality (what the doctor said). It showed absent diastolic velocity. The baby is in the 50th percentile.
My polymyositis is under control. I do not have gest. diabetes (was just tested). And my blood pressure is great - 94/60 this week...and has been good all along. I have gained pretty close to the recommended amount of weight (about 18 lbs).
The doctor told me I won't be going to full term. I am now going in for weekly ultrasound/dopplers. He is having me keep close eye on the kick counts and call if there is a decline or change.
I am in good hands, I know. But this doesn't stop me from being a bit concerned.
Are there any questions or concerns I should bring up when I see him again next week?
With close monitoring, is this something we can overcome? How fast can things decline? Will it be gradual or can things change in a moment's notice? At what point do they decide to deliver?
Thanks for your input!
At Wed Sep 30, 12:37:00 PM 2009,
Kenneth F. Trofatter, Jr., MD, PhD said…
To anonymous Sep 18: This is NOT something you can overcome! It is related to the abnormality of placentation to which we alluded as a possibility in our original response to your concerns discussed in the post above! Your doctors will keep the baby inside you as long as there is no further evidence of fetal compromise and as long as you remain healthy. They will be looking at the fetal Dopplers (umbilical cord, middle cerebral artery, and perhaps ductus venosus), fetal biophysical profile, and the fetal heart rate patterns. I will leave it to them to discuss what changes they will use to decide that the baby is better off out than in! They will also observe you carefully for any evidence of preeclampsia. The baby's condition may change quite rapidly which is why the increased frequency of visits is justified. Thank you so much for letting us know how you are doing and I wish you the best for the rest of the pregnancy. Let us know how things turn out.
Dr T
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