The Pregnant Kidney Patient: An Interview with Madeleine V. Pahl, MD
Madeleine Pahl, MD
Focusing on nephrology patients who become pregnant may seem to be a niche business, but as specialist Madeleine Pahl, MD, tells Renal & Urology News, this population is increasing. In an interview with Delicia Honen Yard, Dr. Pahl, who is Professor of Medicine and Director of the Fellowship Training Program in the Division of Nephrology and Hypertension at University of California, Irvine, in Orange, Calif., explains the unique considerations for nephrologists who treat pregnant dialysis or post-transplant patients.
How did you come to study the effects of pregnancy in kidney disease?
Dr. Pahl: No one has asked me that in a very long time. But years ago, when I was a fellow, I had to take care of a patient on dialysis who became pregnant, and it piqued my interest. It's something that not too many people know about. I started to do a lot more reading and became involved in the care of those patients.
Do you have an even more specific area of interest within this?
Dr. Pahl: You might say dialysis patients who become pregnant.
What is the typical diagnosis of your patients?
Dr. Pahl: Overall, 50% of dialysis patients in the United States are diabetic, but not in this case. But about 40% of dialysis patients of childbearing age who do become pregnant have glomerular nephritis (GN) or lupus. Chronic GN has been reported in the literature around 29%, and the lupus around 9.6%.
How big a segment of the CKD population does this group represent?
Dr. Pahl: I haven't seen that literature, but there have been more than 1,000 live births among kidney transplant patients reported in the literature. That's a lot more than in the dialysis population.
Between 1% and about 7% of dialysis patients of childbearing age have become pregnant, depending on what part of the world you're looking at. In the U.S., the pregnancy rate among these patients used to be reported around 1.5%, but a U.S. registry was set up in 1997 or so, and they reported in 2003 that approximately 2.4% of women of childbearing age in the United States on dialysis have become pregnant. Saudi Arabia reported about 5% in the late 1990s, but I believe it has risen to 7.5%.
What factors are driving these increases?
Dr. Pahl: I think some of the women may be receiving better care, better dialysis. They're more likely to have normal periods than they did before because they're better dialyzed, and because of that they have become fertile.
What are the special concerns for nephrologists in treating pregnant women?
Dr. Pahl: One of the challenges to community nephrologists and to outside dialysis centers is that most experts recommend increasing the dialysis prescription for pregnant women, meaning many of these women should go on dialysis six days a week. That makes it a challenge for the patients and a challenge for the dialysis center to schedule them; these patients now basically take up two spots.
You have to ensure that you carefully monitor the dry weight of these patients, because you have to start increasing dialysis as their pregnancy progresses and they gain weight. Sometimes EPO [erythropoietin] management becomes a little more challenging. You have to monitor phosphorus and calcium. Nutrition is an issue. We don't reuse the dialyzer; you don't want to expose [the fetus] to formaldehyde.
But the biggest concern is that these women have a much higher incidence of preeclampsia, and recent literature has shown that the outcomes are much worse in pregnant women on dialysis than in pregnant women not on dialysis. So it's a challenge: You have to watch for the symptoms and signs of preeclampsia, which might be difficult to determine in dialysis patients.
When the dialysis patient is pregnant, does the nephrologist “outrank” the obstetrician?
Dr. Pahl: If one of our nephrology patients becomes pregnant, she is immediately referred to the high-risk obstetrician, and then we're in constant communication with that specialist—we probably talk to each other about every two weeks. Both our nephrologists and the obstetrician see the patient frequently in the dialysis center, and we work very closely with the obstetrician. If there are any issues, the woman is admitted to the obstetrics service.
I guess if you were going to try to set up some kind of regional management area, the obstetrician may be in charge of ensuring that the pregnancy is progressing adequately, whereas we try to manage the dialysis prescription, which becomes altered in this setting.
In your experience, have these been planned pregnancies?
Dr. Pahl: No. As a rule, women who are on dialysis have classically not thought that they were going to be able to get pregnant, particularly because many had abnormalities of their menstrual periods. But as some of their gynecological issues get controlled, we are seeing pregnant people, but they didn't plan it.
If a nephrologist does have the opportunity to discuss pregnancy ahead of time, what points should be addressed?
Dr. Pahl: In the past, women who had received a kidney transplant were told not to conceive for at least two years post-transplantation, until they were stable. But most recently, I think since 2005 or 2006, that has changed to one year after transplant because outcomes have been relatively good
For the women with chronic kidney disease, you have to counsel them for the potential for adverse risks, which may include worsening hypertension and exacerbation of their disease, such as lupus. They could have adverse obstetric outcomes much more than the general community.
Preeclampsia and preterm labor are the big issues. The big problem with newborns in the renal arena has been “small for gestational age.”
If a woman has a genetic kidney condition, does the nephrologist now have to provide genetic counseling?
Dr. Pahl: There are some diseases for which you can do genetic counseling—for example, polycystic kidney disease. Tuberous sclerosis, all the obvious genetic predispositions, diseases that are autosomal-dominant that can occur in the baby…we give the simple sort of genetic information, and then we have the patient go to counseling. We're fortunate here at UC Irvine to have an excellent genetic counseling group.
So, when pregnant women come to us, we'll send them to the obstetrics service to understand the obstetrics issues, and we'll send them to genetic counseling.