Bauer D C, Brown A N
Department of Medicine, University of California, San Francisco, USA.
Arch Intern Med. 1996 Nov 11;156(20):2333-7.
The appropriate use of specific thyroid function tests to detect thyroid dysfunction remains controversial; some experts recommend both a sensitive thyrotropin (sTSH) test and a free thyroxine (FT4) test, while others recommend an sTSH test alone.
To determine how often sTSH and FT4 tests are ordered simultaneously, how often the results are discordant, and under what circumstances a single test of thyroid function may be sufficient to rule out thyroid dysfunction.
Retrospective descriptive study of all sTSH and FT4 tests performed on adult outpatients during a 6-month period. If both sTSH and FT4 tests were performed on a single serum specimen, the results were classified as concordant (both tests indicating hypothyroidism, hyperthyroidism, or euthyroidism) or discordant. Chart review was performed on patients with normal sTSH results and abnormal FT4 results.
A total of 6551 sTSH and 3518 FT4 tests were performed during the study period. Both sTSH and FT4 tests were ordered together on 3143 specimens (48% and 89% of the total number of sTSH and FT4 tests ordered, respectively) from 2629 patients. Of the sTSH results, 69.8% were within the normal range, and 92.7% of the FT4 results were normal. The concordance between sTSH and FT4 results was 74.3%. Among the 1835 specimens with normal sTSH results, FT4 level was low in 11 patients (0.6%; 95% confidence interval, 0.3%-0.9%) and high in 24 (1.3%; 95% confidence interval, 0.8%-1.8%). Chart review did not disclose any instances when an abnormal FT4 results contributed to the treatment of an individual with a normal sTSH result.
The sTSH test alone, and not the combination of sTSH and FT4 tests, should be ordered in most outpatients. An FT4 test should not be routinely ordered if the sTSH result is normal; at our institution this approach would obviate the need for at least half of the FT4 tests performed each year.
使用特定的甲状腺功能测试来检测甲状腺功能障碍仍存在争议；一些专家建议同时进行敏感促甲状腺激素（sTSH）测试和游离甲状腺素（FT4）测试，而另一些专家则仅建议进行sTSH测试。
确定sTSH和FT4测试同时进行的频率、结果不一致的频率，以及在何种情况下单一的甲状腺功能测试可能足以排除甲状腺功能障碍。
对6个月期间成年门诊患者进行的所有sTSH和FT4测试进行回顾性描述性研究。如果对单个血清样本同时进行sTSH和FT4测试，则将结果分类为一致（两项测试均表明甲状腺功能减退、甲状腺功能亢进或甲状腺功能正常）或不一致。对sTSH结果正常而FT4结果异常的患者进行病历审查。
在研究期间共进行了6551次sTSH测试和3518次FT4测试。来自2629名患者的3143份样本（分别占sTSH和FT4测试总数的48%和89%）同时进行了sTSH和FT4测试。在sTSH结果中，69.8%在正常范围内，FT4结果的92.7%正常。sTSH和FT4结果之间的一致性为74.3%。在1835份sTSH结果正常的样本中，11名患者（0.6%；95%置信区间，0.3%-0.9%）的FT4水平较低，24名患者（1.3%；95%置信区间，0.8%-1.8%）的FT4水平较高。病历审查未发现任何异常FT4结果有助于治疗sTSH结果正常的个体的情况。
在大多数门诊患者中，应仅进行sTSH测试，而不是同时进行sTSH和FT4测试。如果sTSH结果正常，则不应常规进行FT4测试；在我们机构，这种方法每年至少可避免一半的FT4测试。
