carbamazepine levels

[melissalefort]

My daughter (6 months) gets levels drawn about every month. Since she is little and has had blood drawn many times, they have a hard time getting a vein in her arm to give blood and often do a foot prick instead. I've have been told by others at quest that it must be drawn from the arm. Why would this make a difference? Isn't any blood in her body able to measure her levels? If you know the answer, I would really appreciate it. Thanks

[Andrea Lee]

I'm 25 years old and have taken carbamazepine (Tegretol) since I was about 10 (for seizures). I have regular blood tests, but I don't know the specific details about the lab work and/or how they measure the levels. I think this is a question for your daughter's doctor.

[steve s]

Hi,
In addition to the information I sent in reply to your message, it is usual to monitor other haematological and biochemical indicators when a person starts to take carbamazepine, in case there are any adverse effects. This monitoring may be monthly to start with, becoming less frequent in older patients.

Because of the reasons already mentioned, haemolysis, small sample size, contamination with tissue fluid etcetera, these measurements would be unreliable if estimated on a heel-prick. The errors introduced could also make the carbamazepine results inaccurate.

I hope your daughter responds well to her treatment and I wish you both well.
Steve.