Make the Diagnosis: Goiter
The prior probability of a goiter is affected by many variables, including the patient's body surface area, sex, and regional variations associated with the endemic iodine deficiency. Two recent European studies of thyroid volume among community samples of healthy adults give us insight into the prevalence of goiter in the non–iodine-deficient area: 4% of patients in Spain (95% confidence interval [CI], 3%-6%)8 and 10% of patients in France (95% CI, 9%-11%)9 had palpable goiters. Unfortunately, the thyroid volume was not confirmed for patients with palpable goiters. Nonetheless, we can make some inferences that give us good starting points. The WHO defines an iodine-deficient area by the prevalence of goiter in school-aged children. According to normative population values, children who live in a non–iodine-deficient area should have a goiter prevalence of less than 5%.1 Adults might have palpable thyroid glands for reasons other than iodine deficiency, so prevalence values slightly higher make sense. A starting point of 5% to 10% for healthy adults makes sense for the prior probability of a palpable thyroid.
Population for Whom a Goiter Disease Should Be Considered
Symptoms of hyperthyroidism or hypothyroidism
Children, especially those in endemic iodine deficiency locales
Pregnant and lactating women
Patients with excessive radiation exposure
Patients with Down syndrome
Detecting the Likelihood of a Goiter
Because examining children is different from examining pregnant women for thyroid disease, we cannot combine the data (see Table 21-10). The techniques for examination, however, are similar. We have no data for the results of thyroid palpation in non-pregnant adults because epidemiologic studies of normal adults’ thyroid volume exclude those with palpable enlargement.
Table 21-10.Likelihood Ratios for a Palpable Thyroid Gland Indicating a Goiter |Favorite Table|Download (.pdf) Table 21-10. Likelihood Ratios for a Palpable Thyroid Gland Indicating a Goiter
|Palpable Thyroid With Both Lobes > the Volume of the Subject's Distal Thumb (1994 criteria) vs Not Palpable ||LR+ (95% CI) ||LR– (95% CI) |
|Children ||3.0 (2.5-3.5) ||0.30 (0.24-0.37) |
|Pregnancy ||4.7 (3.6-6.0) ||0.08 (0.02-0.27) |
Palpating thyroid tissue in both lobes of a volume greater than the volume of the patient's distal thumb phalanx increases the likelihood of a goiter, but there will be false-positive results.
In epidemiologic research, urinary iodine studies are evaluated along with thyroid palpation.
Original Article: Does This Patient Have a Goiter?
How Large Are These Thyroid Glands?
For each of the following patients, assessment of thyroid size is an important part of ...