Wednesday, April 27, 2005

The Absent Thyroid Lobe or Thyroid Hemiagenisis

The last blog about a patient born with only half of a thyroid, was followed by questions of why, from emailers ?
Well, there are some 100 cases of failure to produce a thyroid lobe.Usually it is in a female, and 75% on the left lobe.There is a high degree of disease in the opposite lobe. The most common disease is Hyperthyroid Graves'. Absent thyroid lobe was found in less than 0.01% of 24,000 screened children. There is an even rarer type, that includes the isthmus. My patient had absent isthmus and left lobe. She also had a nodular cystic goiter in the remaining lobe. The past work up included thyroid scans before and after Bovine TSH Stimulation. Now the ultrasound allows early definitive diagnosis. Failure to know about this can cause patients to become hypothyroid after unilateral lobectomy. If the lobe is absent, the patient needs thyroid hormone therapy. Usually, if the lobe is normal, and present, the patient may not need thyroid hormone after lobectomy.


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