How does a doc test for thyroid problems?

Tests . Usually severa ways -- good history and exam always comes first. Lab tests usually follow including tests for function and antibodies. It may stop there or an ultrasound may be necessary. In some cases if ultrasound shows large nodules, a fine needle biopsy would be the next. Radio-active iodine scans are usually reserved for hyper functioning nodule detection.
+blood, u/s, scans. A thorough history and physical is the first step, then some simple blood test if thyroid dysfunction is suspected. If you have some lump/bump (nodule) on your thyroid, you may need to get an u/s or cat-scan etc..Depending on the finding, a biopsy, or nuclear-scan may be needed to see if it function normally or suspect of cancer etc..Consult doc if you have concerns. Good luck.