Serum thyrotropin concentration as a novel predictor of malignancy in thyroid nodules investigated by fine-needle aspiration.
BACKGROUND
Thyroid nodules and goiter are common, and fine-needle aspiration biopsy (FNAB) is the first investigation of choice in distinguishing benign from malignant disease.


OBJECTIVE
The objective of the study was to assess whether simple clinical and biochemical parameters can predict the likelihood of thyroid malignancy in subjects undergoing FNAB.


METHODS
The design was a prospective cohort.


METHODS
The study was conducted at a single secondary/tertiary care clinic.


METHODS
One thousand five hundred consecutive patients without overt thyroid dysfunction (1304 females and 196 males, mean age 47.8 yr) presenting with palpable thyroid enlargement between 1984 and 2002 were evaluated by FNAB of the thyroid.


METHODS
There were no interventions.


METHODS
Goiter type was assessed clinically and classified as diffuse in 183, multinodular in 456, or solitary nodule in 861 cases. Serum TSH concentration at presentation was measured in a sensitive assay in patients presenting after 1988 (n = 1183). The final cytological or histological diagnosis was determined after surgery (n = 553) or a minimum 2-yr clinical follow-up period (mean 9.5 yr, range 2-18 yr).


RESULTS
The overall sensitivity and specificity of FNAB in predicting malignancy were 88 and 84%, respectively. The risk of diagnosis of malignancy rose in parallel with the serum TSH at presentation, with significant increases evident in patients with serum TSH greater than 0.9 mU/liter, compared with those with lower TSH. Binary logistic regression analysis revealed significantly increased adjusted odds ratios (AORs) for the diagnosis of malignancy in subjects with serum TSH 1.0-1.7 mU/liter, compared with TSH less than 0.4 mU/liter [AOR 2.72, 95% confidence interval (CI) 1.02-7.27, P = 0.046], with further increases evident in those with TSH 1.8-5.5 mU/liter (AOR 3.88, 95% CI 1.48-10.19, P = 0.006, compared with TSH < 0.4 mU/liter) and greater than 5.5 mU/liter (AOR 11.18, 95% CI 3.23-8.63, P < 0.001, compared with TSH < 0.4 mU/liter). Males (AOR 1.8, 95% CI 1.04-3.1, P = 0.04), younger patients (AOR 1.1, 95% CI 1.01-1.15, P = 0.025), and those with clinically solitary nodules (AOR 2.53, 95% CI 1.5-4.28, P = 0.001) were also at increased risk. Based on these findings, a formula to predict the risk of the diagnosis of thyroid malignancy in individual patients, taking into account their gender, age, goiter type determined clinically, and serum TSH, was calculated.


CONCLUSIONS
The risk of malignancy in a thyroid nodule increases with serum TSH concentrations within the normal range. In addition to patient's gender, age, and goiter type, the serum TSH concentration at presentation is an independent predictor of the presence of thyroid malignancy. We propose that these simple clinical and biochemical factors can serve as an adjunct to FNAB in predicting risk of malignancy.
Boelaert
K
K
Division of Medical Sciences, University of Birmingham, Queen Elizabeth Hospital, Edgbaston, Birmingham B15 2TH, United Kingdom. k.boelaert@bham.ac.uk
Horacek
J
J
Holder
R L
RL
Watkinson
J C
JC
Sheppard
M C
MC
Franklyn
J A
JA
D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D044963:Biopsy, Fine-Needle / Q000379:methods*; D002277:Carcinoma / Q000175:diagnosis / Q000453:epidemiology; D002648:Child; D015331:Cohort Studies; D005260:Female; D006044:Goiter, Nodular / Q000175:diagnosis / Q000601:surgery; D006801:Humans; D008297:Male; D008875:Middle Aged; D011230:Precancerous Conditions / Q000175:diagnosis*; D011379:Prognosis; D011446:Prospective Studies; D015203:Reproducibility of Results; D012307:Risk Factors; D012680:Sensitivity and Specificity; D012727:Sex Characteristics; D013964:Thyroid Neoplasms / Q000175:diagnosis / Q000453:epidemiology; D016606:Thyroid Nodule / Q000175:diagnosis / Q000601:surgery*; D013972:Thyrotropin / Q000097:blood*
D013972:Thyrotropin