Jack P

Member
10+ Year Member
Jul 19, 2006
49
1
Status
Medical Student
Hi all, I'm new to this forum and in the middle of study for Step 1. Took the form 1 on friday and am going over my answers...I found a bit of a contradiction in a question regarding hereditary angioedema.

The question (paraphrased to protect copyright ;) ): Young girl with an acute onset of facial swelling and dyspnea. Hereditary Angioedema is suspected (C1 esterase inhibitor), what will be found in serum?
1. Decreased serum C4
2. Increased serum properdin
3. Normal C1q
4. Normal C1s
5. Normal C2

In a bit of research I found out that:
Lab Studies:

* Routine laboratory tests are usually normal, although a leukocytosis may occur with gastrointestinal episodes. Elevation of the hematocrit may be observed because of intravascular fluid loss.

* Type I HAE

o C1-INH level is low.

o C4 and C2 levels are low.

o C1q level is normal.

* Type II HAE

o C1-INH level is normal or elevated but dysfunctional.

o C4 and C2 levels are low.

o C1q level is normal.

* Type III HAE

o C1-INH level is normal.

o C1-INH functional assay is normal.

o C4 level may be normal.
So here...answers 1 and 3 could be true? I could be totally off but does anyone have an answer?
 

trudub

Senior Member
7+ Year Member
15+ Year Member
Oct 23, 2003
337
2
37
Nebraska
Visit site
Status
From a basic science standpoint, I would assume the answer is low C4. That makes sense since the C' pathway is uninhibited it uses up the C4. That would also make the C1q levels high. So, without any outside knowledge that is what I assume the answer is. Maybe for some reason the C1q levels are actually normal but the C4 levels should definitely be low.
 
OP
Jack P

Jack P

Member
10+ Year Member
Jul 19, 2006
49
1
Status
Medical Student
Definitely agree on the low C4...just got confused on the normal C1q since I've found examples in the literature that it can be the case. But I guess you have to ask...what is the most common finding? I found the "lab studies" from emedicine which is usually quite a good resource...better than wikipedia anyway!