TPO antibody test : what’s wrong and how can we make it right?
I am not a big fan of measuring TPO antibodies. For starters, we can’t treat it. Secondly, even if it can be used for prognostication — what good is knowing what will happen if we can’t do much about it? There is hardly any evidence to suggest there is a lead time advantage with measuring these antibodies.
On the other hand, increasingly endocrinologists have to interpret the anti TPO antibody levels, which they themselves didn’t advise. This is particularly common in young women, who are either planning pregnancy or are already pregnant.
The typical scenario is a patient who seems scared because — her anti TPO antibody level has been reported to be in hundreds. Say 800. Obviously they may not know the signficance of the test, but they can see the lab cut offs which are printed in the report. This is a much smaller number. Naturally they think something is very wrong with them, and they get scared.
This leads us to a fundamental question
Does reporting of anti TPO antibody test as a number offer any advantage over reporting it as positive/negative?
The answer can’t be universal. The number may be helpful if we suspect Hashimoto’s encephalopathy in a patient. It may not be very useful in a young anxious woman planning pregnancy.
Several options exist
- Print a disclaimer that the number is nothing to be alarmed about. This is meant to reassure patients (and non-specialist doctors too)
- Use branching logic to report
If patient pregnant → check if antibody > predetermined cutoff → if yes, report as positive. If not report as negative.
This leads to another question — what is the “predetermined cutoff”?
These things are, in my opinion, duct-taping — trying kludgy solutions to solve a problem that shouldn’t exist in the first place
Prevention is better than cure. We need to educate doctors not to order tests unless there is a real need.