IVIG

Lucas came home Saturday afternoon with ANC 360 -- low but stable.   I took him for finger poke CBC today and the oncology phone nurse told me his IGG results together with the CBC result.

ANC is 890 and we will restart chemo with oral MTX 2pills/week on Tuesdays, and 6MP 1/4 pill/day, 6 days a week.  So essentially 45% on MTX, and 25% 6MP.

The bigger question is for IVIG.  His IgG level is 221.

The concept of low ANC is neutropenia, which is different from low immunoglobulin G.

For low IgG, he can receive a blood product called IVIG to boost his IgG level, which in turn helps with his immune system.

I called our oncologist today and got some questions answered:

Q: How often do kids under chemotherapy need IVIG?
A: It depends.  For infant or Down Syndrome ALL patients, it's quite common for them to need IVIG.  For the rest, it's not very common.  Usually doctors don't test IgG level unless a patient gets sick often and needs to have chemo hold often.
My interpretation: I really pushed for the test.  I know I'm the kind of parent who does lots of reading and probably get too much information if there's such a thing.  A lot of ALL parents never heard of IgG or IVIG.  IVIG is expensive (about $10k per dose depending on the size of patients) and the doctors need to prove to insurance company that it's needed.  IVIG also has its risks (mostly allergic reaction).  Some people with low IgG do not get sick often.  Quoting a parents on ALL LIST: "Even if his IgG levels are low, unless he's getting sick from it, they aren't going to give him IVIG (a blood product) unless he really needs it.  IVIG comes with its own set of risks  and issues -- no blood product is risk free.  And it's not really the number of antibodies (IgG, etc.) in the body that's important, it's how well they function.  Someone can have very low IgG numbers and not get sick as they are functioning well, whereas someone else with higher IgG numbers can be very sickly because theirs don't function properly.  "

Q: How often is IVIG given and how long will the regimen last?
A: It's usually given every 4 weeks (schedule sync with Vincristine).  IgG level will be monitored and the schedule might become every 8 weeks.  For some kids, IVIG needs to be given a few months after the chemo ends.

Q: How soon will IVIG start to work?
A: Within a day that it's given, it will start to work to boost immunity.

Q: You suggested us to wait for two weeks to get IVIG together with our once-every-four-weeks Vincristine and Pentamidine.  I feel we should act now since we know he is low on IgG.  Do you feel the urgency?
A: Unless you absolutely feel that you can't wait for two weeks, I don't see the urgency.  His IgG is 221 so he has some immunity.
My own take: If he gets it on 10/29, he will be ready for the flu season.  We will be extra cautious until then.

Q: Will one develop dependency on IVIG?
A: Not likely.  Chemo is what's suppressing the IgG level.  As soon as the drug gets out of his system, his IgG level will improve.