Common Patterns of Thyroid Function Tests and Their Reasonable Request

Thyroid disorders including hypothyroidism and hyperthyroidism are common condition in the world and the right diagnosis and treatment are important. Now a days screening for thyroid dysfunction recommend only in a specific situation, thus unnecessary tests could have undesirable outcomes such as improper sampling and costs related to long-term follow-up which could affect patients and health system. (5-10. Except for cases of inappropriate doing thyroid function tests, it should be noted that TSH measurement alone has a high sensitivity for the initial investigation and diagnosis of thyroid diseases (7, 10) so, in context of abnormal TSH it is necessary to measure other thyroid hormones. It is worth mentioning that in the case of hospitalized patients, thyroid laboratory disorders are more common without the presence of thyroid gland homeostasis disorder (11), which shows the necessity of paying more attention to the target population in requested examinations. Therefore, according to the importance of the subject, the present study investigated the request patterns of thyroid function tests and the logical cases of their request in Tehran's Firouzgar Hospital affiliated to Iran University of Medical Sciences, during the second 6 months of 2017. In this cross-sectional study, 484 inpatients for whom each of the Thyroid function tests was requested selected as a sample by census and included in the study. The samples included in the study were evaluated by clinical evaluation and history taking with the aim of finding the indications for thyroid test request, and if it is possible to diagnose thyroid function disorders in the next stage of the requested tests in terms of compliance with the algorithms and instructions The existing one was checked. Finally, if the laboratory tests lead to the final diagnosis, the proportionality of the requested functional test with the final diagnosis is checked.

In this study, the definition of essential thyroid tests included the patients who have a known thyroid disease based on previous history or hospital records and clinical examinations, or there is a high clinical suspicion for their thyroid disease, it is reasonable to perform TSH & T4 & T3RU or TSH & FT4 tests. SPSS version 24 software was used for statistical analysis of data.

The average age of the participants in the study was 54.2 years with a standard deviation of 17 years and 59.4% were female. In total requested tests the most patients 101 (20.7%) were hospitalized in the neurology department and the least patients 2 (0.4%) were from the toxicology ward. Out of a total of 488 patients for whom thyroid tests were requested, only 259 patients were found to have a specific reason for requesting these types of tests based on the clinical records, history or clinical examination, and 99 patients (38.2%) were hypothyroid. TSH was requested for 477 patients, and the mean TSH was 3.583. Out of a total of 69 patients whose treatment status changed, 27 patients (39.1%) had an increase in the treatment dose. The most patients whom TSH was requested without indication, most cases (26.3%) were admitted to the neurology department. The most common pattern of requesting thyroid tests in people participating in our study was the combination of TSH, T3, T4. In this study, 69 patients out of 488 patients for whom thyroid tests were performed treatment was changed. Out of 194 patients who had a logical reason to request thyroid tests based on their previous history of thyroid diseases or current examination and history, only 54 patients, equivalent to 27.83%, have undergone treatment change.

The purpose of this study was to examine the patterns of requests for thyroid function tests and to determine the logical cases of their requests in Firozgar Hospital in a period of 6 months. Considering that hypothyroidism and hyperthyroidism have a significant prevalence in the world and also due to the high prevalence of iodine deficiency in our country, thyroid diseases are also common. Since the symptoms of thyroid diseases are mostly non-specific and shared with other diseases, it is better to avoid unnecessary sampling and related problems, including high cost, the need for long follow-up and the patient's and family's concern about the results. As a result of the tests, the measurement of thyroid function tests should be used only in reasonable cases and with a suitable pattern. There is no need to check thyroid tests in all hospitalized patients who are unrelated to thyroid diseases. In general, it seems that the measurement of thyroid tests in logical cases and with the correct pattern has positive results for the patient and health system. In the current study, thyroid tests were requested for 488 patients, compared to the study of Small et al., it can be said that the sample size of our study was slightly smaller than that study. (11) About 60% of the studied patients were women, which can indicate that thyroid tests are more common in women than in men, regardless of whether the request is reasonable or unreasonable. In terms of average age, it can be stated that thyroid tests are performed at different ages of people, although the average age in this study was 54 years, but a wide standard deviation of 17 years was also observed among patients. Regarding the frequency of unnecessary requests, T3 with 99.2%, TSH with 60.6%, and T4 with 59.4%, T3RU with 59%, and Anti TPO Ab with 38% had the highest to lowest amount respectively. It should be noted that all requests for fT3 and fT4 tests were unnecessary. In our study, the most number of cases for whom thyroid tests were requested were hospitalized in the departments of neurology, endocrinology, neurosurgery, and neurology ICU, respectively. It seems that this amount can be reduced if endocrinologists are consulted about the indication of requesting thyroid tests. The most common request patterns for thyroid function tests were TSH&T4&T3 with 69.87% and TSH&T4 with 15.57% respectively. In the study of Roti et al., the most common requested pattern with 56% was the combination of TSH, T3, T4, and for this reason, the two studies are similar (10). was requested, 27.83% of them had a change in their treatment procedure, which is higher compared to the study of Mr. Small et al., where only 2% of patients had a change in treatment (11). In our study, among the patients whose test results were in favor of changing the treatment or starting of thyroid medication or increasing the dose of drugs was the most common case with 39.1%. In this study, among patients who had a history of thyroid problems, TSH and T4 tests were reported as the most frequently performed tests among these people.In general, based on the obtained results, it seems that requesting all thyroid indicators at the same time is a common finding. It can also be added that the unusual patterns of requesting thyroid function tests, multiple cases of requesting thyroid function tests, and the non-optimal contractual TSH threshold level cause unnecessary requests for thyroid function tests. One of the most important limitations of this type of study is that the algorithms and instructions are different in different field of medicine and the way of requesting thyroid function tests may be different between two medical specialties. Another limitation of this study is the lack of sufficient previous studies. One of the final suggestions can be the point that cases of inappropriate requests for thyroid hormones in free hormones are taken at the same time as taking total hormone levels, which are the most suitable places for intervention to reduce cases of inappropriate requests for thyroid function tests. It is also suggested that studies with a larger sample size and a longer follow-up period be conducted in the future.