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Arch Intern Med. 2007 Jul 23;167(14):1533-8.

Serum thyrotropin measurements in the community: five-year follow-up in a large network of primary care physicians.

Author information

1
Research & Health Planning Department, Health Planning and Policy Wing, Clalit Health Services, 101 Arlozorov St, PO Box 16250, Tel Aviv 62098, Israel. josephm@clalit.org.il

Abstract

BACKGROUND:

Subclinical thyroid disease is common; however, screening recommendations using serum thyrotropin (TSH) level determinations are controversial.

METHODS:

To study the use of serum TSH by primary care physicians and define populations at risk for having an abnormal TSH level at follow-up, based on initial TSH levels, we conducted an observational study of a large health care database in the setting of a health management organization. All outpatients without thyroid disease or pregnancy or taking medication that may alter thyroid function in whom the TSH level was measured in 2002 and during 5-year follow-up were included in this study. Repeated TSH level determinations were compared with the initial TSH level values.

RESULTS:

In 422 242 patients included, 95% of the initial serum TSH concentrations were within normal limits (0.35-5.5 mIU/L), 1.2% were decreased (<0.35 mIU/L), 3.0% were elevated (>5.5 to <or=10 mIU/L) and 0.7% were highly elevated (>10 mIU/L). In 346 549 patients without thyroid-specific medications, the TSH levels became normal in 27.2%, 62.1%, and 51.2%, whose initial serum TSH level was highly elevated, elevated, and decreased, respectively, and remain normal in 98% of the patients with normal initial TSH levels. When the initial serum TSH level was elevated, patients in the highest quintile of this group, who had a shorter interval between the first and second measurements, had a higher probability of a second highly elevated TSH concentration (P < .001).

CONCLUSIONS:

When the serum TSH level is normal, the likelihood of an abnormal level within 5 years is low (2%). More than 50% of patients with elevated or decreased serum TSH levels have normal levels in repeated measurements.

Comment in

PMID:
17646608
DOI:
10.1001/archinte.167.14.1533
[Indexed for MEDLINE]

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