WARNING:  This is a very controversial subject and if you are a patient you must contact your doctor for guidance.  The workup of a thyroid nodule is rapidly changing and the information provided below should be considered out of date at the time it is posted.   

Incidence of Thyroid Nodules:  At the time of their death, 30% to 60% of individuals have at least one thyroid nodule.     View Article 1997 Annals of Internal Medicine

Patient Examination:  The age, sex of the patient, along with the size of nodule are important.    The older the patient the more malignant are the cancers.   Males tend to have more aggressive tumors than females.   In addition, larger tumors which are found to be cancers are more likely to spread.

Hoarseness or dysphasia (trouble swallowing) may indicate a malignancy.  A benign thyroid goiter, even if huge,  seldom causes these symptoms. 

Evaluation and Management:   The only definitive diagnostic test and treatment is removal of the thyroid lobe.   However, this procedure has significant risks (see Thyroidectomy Page) and cannot be performed on half the population.     

Thus, how do you workup the patient and who do you operate on?      GO TO AHRQ - National Guideline Clearinghouse

If a true vocal cord paralysis, suspicious neck nodes, distant spread or a hard and fixed mass is present, excision should be strongly considered because the likelihood of malignancy is very high. 

The procedure of choice in the evaluation of a thyroid nodule is a fine needle biopsy.   It is far more accurate than thyroid scans and has largely replaced thyroid scans for this indication.   Using a fine needle biopsy has a false-negative rate of 1% to 11% and a false-positive rate of 1% to 8%.  View Article 1993 Annals of Internal Medicine    However, this test is highly dependent upon the skill of the administrator and pathologist.   This technique also has difficulty distinguishing between  a benign and malignant follicular lesion - see below. 

Now, let's look at thyroid cancers.  There are in general two types.  Those which are low-grade (papillary or follicular) and those which are very very deadly – analplastic or undifferentiated thyroid carcinoma.   Patients with the later diagnosis almost universally have a rapid and progressive downhill course.   The low-grade malignancies can still be dangerous.  However, in patients under the age of 45 the survival rate is 100% despite the extent or spread of the disease (see Thyroid Cancer Survival Page )

Fine needle aspiration can fairly accurately distinguish between benign and malignant, papillary, medullary and anaplastic/undifferentiated lesions.   Those lesions suspicious of cancer should be excised.  The problem arises when one is dealing with a follicular neoplasm.  Some recommend excision of Hurthle cell neoplasms (a type of well-differentiated follicular lesion.  (Note:  Fine needle aspiration of patients with thyroiditis can be confused with Hurthle cell neoplasms.  Thyroid antibodies should always be obtained to help in this differential diagnosis.)   In follicular lesions, I sometimes use size, sex and age of the patient to help in management decisions.   However one needs to remember that if a follicular neoplasm is found on needle biopsy that some studies have found an incidence of carcinoma as high as 25% in these patients.  View Abstract
  
NOTE:  A needle biopsy which shows benign follicular cells may be followed conservatively.  However, if a follicular neoplasm is found, one cannot reliably tell benign verses malignant. 
 
Thus, if one is under the age of 45, female, and has a small follicular nodule, less than 2 cm, then one may elect to suppress the patient’s thyroid and observe with serial ultrasound examinations.  If the nodule increases in size, then it needs to be removed.   Remember, under the age of 45, a follicular cancer has a 100% survival rate regardless of the size and spread.  If the patient has a larger nodule, is a male, or is over the age of 45, then removal may be necessary.    

Patients with a positive needle biopsy need to have a total thyroid lobectomy for diagnosis and further management if a cancer is found.  Patients with a negative needle biopsy can be followed with serial ultrasounds to measure any change in size of the nodule.  Thyroid suppression therapy is controversial and AHRQ recommends against the routine use for benign nodules.  

Thyroid suppression has been implicated in the development of osteoporosis.  Although some studies have failed to find a relationship.  View Abstract 1998 Gynecol Endocrinol ,   View Abstract 1995 Thyroid , View Article 1994 Clinical Endocrinology & Metabolism , View Article 1995 Hormone Metabolic Research     

It is prudent to be on Vitamin-D and calcium and to perform bone scans for the development of osteoporosis.   Other studies have shown that this is a significant clinical problem.   Mohammadi, et al., recommends checking a bone scan after six months of therapy.  View Abstract 2007 Theoretical Biology & Medical Modelling    Other articles support the view that thyroid suppression can cause osteoporosis.   View Article 1990 British Medical Journal   Prevention of bone loss from thyroid suppression therapy  View Article 1996 J Clinical Endocrinology & Metabolism   Some researches even found non-suppressive therapy may cause osteoporosis   View Article 2000 European Journal of Endocrinology 

Exceptions:   Patients at high risk for thyroid malignancy are those with a history of head and neck irradiation, a positive PET Scan, patients with familial adenomatous polyposis, a family history of medullarly carcinoma or a male over the age of 60 with a thyroid nodule.   These patients need to be worked up aggressively for consideration of thyroid lobectomy.     

Incidentalomas.  Thyroid nodules found on CT or PET scans when looking for other disease are called Incidentalomas.    Those found by CT scan have the same risk of malignancy as those found on ultrasound or physical exam.    Workup for very small tumors less than 1.0 cm is often watchful waiting since they often cannot be accurately needle biopsied even with ultrasound guidance.    

However, those found on PET scan are felt to have a hyper-metabolic rate and  thus may have a higher risk of being cancer.  Further workup followed by possible operative intervention of these nodules is necessary.    View Article 2008 Surgical Rounds     View Abstract 2007 Annals of Surgical Oncology