Ultrasound thyroid screening targets patients on lithium

Ultrasound is more accurate than conventional screening for detecting goiter in patients on long-term lithium therapy, according to a recent study from Germany. Lithium therapy inhibits normal function of the thyroid, but clinical inspection and palpation missed goiter in some patients in whom it was detected with ultrasound.

Dr. Michael Bauer and colleagues with the International Group for the Study of Lithium Treated Patients published the results of their study in the Journal of Affective Disorders in March. They recruited 96 consecutive patients from the Berlin Lithium Clinic. Some had been diagnosed with bipolar, major depressive, and schizoaffective diseases. As these patients often have trouble reliably taking their prescriptions, only those with adequate serum lithium levels documented continuously for at least six months were entered into the study.

As a control, exams for goiter were also performed on 96 subjects matching the gender and age of the lithium patients. Patients in both groups were at least 18 years old and residents of Berlin and surrounding areas.

Clinical inspection and palpation detected goiter in 24 of the lithium-treated patients, but ultrasound exams found 53 cases of goiter. This means that 54% of cases were overlooked by clinical inspection and palpation. In the control group, ultrasound detected 19 cases of goiter, while clinical inspection and palpation found 12 cases, so only 36% of cases were missed in this group.

A subgroup of the 96 patients on long-term lithium treatment were already taking levothyroxine, a thyroid hormone prescribed to treat hypothyroidism and goiter. Yet goiter was detected in 37% of patients in this subgroup. All patients who were not taking levothyroxine had significantly higher thyroid-stimulating hormone basal levels than did normal controls - a warning sign of thyroid disease.

This study did not control for other factors that might affect the prevalence of goiter, such as dietary issues, smoking, or iodine intake, and the patients on lithium were also being treated with additional psychotropic medications. The researchers concluded, however, that all patients on long-term lithium treatment should be regularly screened using ultrasound, to improve the early detection of goiter. Their study pointed out that other methods for detecting goiter are not sufficient for patients taking lithium long-term.