Abstract
BackgroundSubclinical hypothyroidism is an elevation in serum thyroid-stimulating hormone above the upper limit of the reference range (0.45–4.5 mIU/L) with normal serum TT4 and TT3 concentration. The most important implication of subclinical hypothyroidism is high likelihood of progression of clinical hypothyroidism.MethodsInstitution-based cross-sectional study was conducted on medical records of patients referred at endocrine clinic Tikur Anbesa Specialized Hospital, Addis Ababa from 2010 to 2016. This study was conducted from normal ambulatory patients who have come in the hospital outpatient department since they experienced abnormality on their health status. During the study period, patients were complaining about their clinical symptoms. A total number of 9000 patients were included. Patients’ card was retrieved by using standard extracted formats to collect socio-demographic and clinical information and laboratory measurements. Serum TSH, TT4, and TT3 levels were determined by electro-chemiluminescence immunoassay method on ECLIA 2010 fully automatic analyzer at TASH nuclear medicine. SPSS 20 version software was used for analysis, and chi-square test was used to check the association between dependent and independent variables.ResultsThe overall prevalence of subclinical hypothyroidism evaluated to be 582 (6.47%), 4.6% in females and 1.9% in males. Four hundred and thirty-one (74%) patients had serum TSH levels between 5 and 10 mIU/L, and the average TSH level of subclinical hypothyroid patients whose age was ≥ 40 differ significantly from that of subclinical hypothyroid patients whose age was < 40. The average TSH level among female patients whose age are ≥ 40 differed significantly from their counterparts. Subclinical hypothyroidism patients more often reported having dry skin, poor memory, fatigue, cold intolerance, constipation, and hoarseness.ConclusionThe overall prevalence of ScHt was 6.5% where females showed higher level than males. Age ≥ 40 became independent factor of subclinical hypothyroidism. The higher prevalence of subclinical hypothyroidism in this study could become a predictor for overt hypothyroidism, so screening for subclinical hypothyroidism prevents the later development of complicated overt hypothyroidism.
Highlights
Subclinical hypothyroidism is an elevation in serum thyroid-stimulating hormone above the upper limit of the reference range (0.45–4.5 mIU/L) with normal serum Total thyroxine (TT4) and TT3 concentration
Since no data is available on Sub-clinical hypothyroidism (ScHt), this study provides a preliminary understanding of magnitude of ScHt and age and sex impact on its level of [22]
A total of 9000 patients included in this study, of which 582 study subjects were identified with subclinical hypothyroidism with a prevalence rate of 6.47%
Summary
Subclinical hypothyroidism is an elevation in serum thyroid-stimulating hormone above the upper limit of the reference range (0.45–4.5 mIU/L) with normal serum TT4 and TT3 concentration. Sub-clinical hypothyroidism (ScHt) is a commonly encountered laboratory finding in clinical practice, defined biochemically as the finding of a raised serum thyroid-stimulating hormone (TSH ≥ 4.5 mIU/L) above the reference range from normal circulating levels of total thyroxine (T4) and triiodothyronine (T3) (TT4 = 62–141 nmol/L and TT3 = 1.1–3.2 nmol/L). Subclinical hypothyroidism is the most prevalent thyroid disorder affecting 3–12% of the adult population [3,4,5,6,7,8,9,10,11], and the incidence of subclinical thyroid diseases or their progression is baseline TSH level, old age, female sex, and the presence of thyroid autoantibody [12]. Its prevalence among men over the age of 74 years (16%) was almost as high as it was in women of the same age (21%) [8]
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