|LETTERS TO THE EDITOR
|Year : 2020 | Volume
| Issue : 1 | Page : 166
Response to letter to the editor
Prakas Humar Mandal
DM (Clinical Hematology), Associate Professor of Hematology, Nil Ratan Sircar Medical College and Hospital, Kolkata, West Bengal, India
|Date of Submission||20-Feb-2020|
|Date of Decision||26-Feb-2020|
|Date of Acceptance||28-Feb-2020|
|Date of Web Publication||20-Jun-2020|
Dr. Prakas Humar Mandal
DM (Clinical Hematology), Associate Professor of Hematology, Nil Ratan Sircar Medical College and Hospital, Kolkata, West Bengal
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Mandal PH. Response to letter to the editor. Arch Med Health Sci 2020;8:166
First of all, we want to clarify our position regarding our thyroid function tests as per research methodology undertaken. All tests have been carried out on Access 2 Immunoassay System, Beckman Coulter and strict standards were followed regarding collection of samples and during tests. As per the literature mentioned in TSH IRMA KIT IM3712, IM3713, the following values obtained with healthy subjects are indicative only
- Euthyroid (n = 127) 0.17 - 4.05 mIU/L
- Hyperthyroid (n = 71) ≤ 0.15 mIU/L
- Untreated hypothyroid (n = 58) > 5 mIU/L QUA
It also mentioned that each laboratory can establish their own reference values.
The following grades of hypothyroidism in patients with thalassemia major have been identified:
Sub-biochemical hypothyroidism consists of an exaggerated TSH response to TRH test in the presence of normal TSH and FT4; Sub-clinical hypothyroidism is a combination of high TSH (> 4.2 mIU/L and <10 mIU/L) with normal FT4 levels; Overt (clinical) hypothyroidism is a combination of high TSH (TSH >10 mIU/L) with low FT4. (1)
Normal range of the test assay used in our study as per study by De Sanctis et al:
- TSH is 0.34–4.20 μIU/ml
- FT4 is 0.58–1.64 ng/dl
- T3 is 2.39–6.78 pg/ml
Dr. Pranab Kumar Sahana, DM (Endocrinology), co-author of the present study, was closely involved with the standardization and precision of the thyroid function tests.
Another very pertinent question raised was the issue of thyroid reference values (TRV) used by our study. We have consulted our endocrinologist (Dr. Pranab Kumar Sahana) regarding these issues and he has opined that such reference values for age, sex and ethnicity are not routinely followed in clinical practice; however they are soon to be incorporated after results are harmonized in large clinical trials.
Besides we also want to clarify certain points. If we consider the mean ± SD age of patients was 19.74 ± 7.52 years (range: 12–28 years), there is no restriction for usage of thyroid test values used by us, as the cohort does not have any patients less than ten years or more than sixty years. Onsesveren et al. from his study in paediatric population quoted that, considerable differences exist in the reported reference ranges for childhood TSH and fT4 across and within age ranges and assays.
Next we come to female cohort of Eβ thalassemia patients, first of all we have excluded any patients with pregnancy but an interesting study by Sekhri et al. in from India, has concluded that trimester-specific reference intervals for thyroid tests during pregnancy have been established for pregnant Indian women serially followed during pregnancy using 2.5th and 97.5th percentiles but study population comprised of eighty-six pregnant ladies.
We have come across an interesting study from India by Marwah et al. among four thousand patients which concludes thatthis community based study in Indian adults has established mean reference intervals for FT3, FT4 and TSH for different age groups for both sexes separately using strict exclusion criteria. These can be used as reference norms for Indian adults however their limitations mentioned in their paper suggested that the normal reference ranges may be biased by using the kit reference ranges to exclude subclinical and overt hypo- or hyperthyroidism as was done in the present study. This can be considered a limitation of the study was published.
Based on these heterogeneities and considering our limited available facilities we have adhered to the thyroid function values by the kit provided.
| References|| |
De Sanctis V, Soliman AT, Canatan D, et al
. Thyroid Disorders in Homozygous β-Thalassemia: Current Knowledge, Emerging Issues and Open Problems. Mediterr J Hematology Infect diseases 2019;11:e2019029. doi:10.4084/MJHID.2019.029.
Onsesveren I, Barjaktarovic M, Chaker L, de Rijke YB, Jaddoe VWV, van Santen HM, et al
. Childhood thyroid function reference ranges and determinants: a literature overview and a prospective cohort study. Thyroid 2017;27:1360-9.
Sekhri T, Juhi JA, Wilfred R, Kanwar RS, Sethi J, Bhadra K, et al
. Trimester specific reference intervals for thyroid function tests in normal Indian pregnant women. Indian J Endocr Metab 2016;20:101-7.
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Marwaha RK, Tandon N, Ganie MA, Mehan N, Aparna S, Garg MK, et al
. Reference range of thyroid function (FT3, FT4 and TSH) among Indian adults. Clin Biochem 2013; 46: 341-5. DOI: 10.1016/j.clinbiochem.2012.09.021