Abstract
Objective:To determine the frequency, modes of clinical presentation and indications for replacement therapy in a cohort of patients with subclinical hypothyroidism (SCH).Methods:This study was conducted at the Endocrine and Diabetes Unit of Jinnah Postgraduate Medical Centre from September 2007 – October 2015. This was a retrospective chart analysis of prospectively collected data in whichthe medical records of 4448 patients who had presented to the Endocrine Clinic from 2007 to 2015 were reviewed. A total of 2760 (62.05%) patients were diagnosed withthyroid disorders, whereas 260 (9.42%) patients had SCH. The SCH patients were between the age of 12 to 70 years; TSH was> 4mIU/l with normal levels of FT3 and FT4. Patients were enrolled using a predesigned structured proforma. Those having chronic systemic diseases were excluded from this study. SPSS 13 was used to evaluate the data.Results:Femalepatients comprised93.8% (244 patients) of those with SCH, whereas only 6.2% (16 patients) were male. Common presenting symptoms were, lethargy in 146 patients (56.2%); increase in weight in 102 patients (39.2%) and menstrual irregularities in 90 patients (34.6%). TSH level of < 10mIU/l (4 - 10) was seen in 177 patients (68.1%) and 83 patients (31.9%) had TSH ≥ 10mU/l. Thyroxine was given to 183 (70.4%) of these patients. Common treatment indications were TSH of ≥ 10, which was seen in 83 patients (31.9%), subfertility in 32 patients (12.3%), troublesome symptoms suggestive of hypothyroidism in 31 patients (11.9%) and high titers of antibodies in 23 patients (8.8%).Conclusion:SCH is frequently seen in our population, with most patients complaining of lethargy. The most common treatment indications were a TSH ≥ 10mIU/l, whereas troublesome symptoms of hypothyroidism and subfertility were the common treatment indications in patients who had a TSH of < 10mIU/l.
Highlights
Subclinical hypothyroidism (SCH) is a disorder of the thyroid gland characterized by elevated TSH and normal FT3 and FT4
The Whickham survey reported that a twofold rise in serum TSH would increase the probability of developing overt hypothyroidism from 1to 4%; this risk further increased to 38% if positive for TPO antibodies. These results suggest that if a population is followed, a significant number of subclinical hypothyroidism (SCH) cases may develop overt hypothyroidism.[3]
SCH is frequently seen in our population, but is often asymptomatic or there are vague symptoms leading to the diagnosis being missed
Summary
Subclinical hypothyroidism (SCH) is a disorder of the thyroid gland characterized by elevated TSH and normal FT3 and FT4. The prevalence of SCH is reported to be around 4-10% in the adult population, this varies with different populations, with more cases occurring in iodine sufficient areas.[2,3,4] The prevalence is even higher in people taking thyroid medications.[5] Like other thyroid disorders, SCH is much more common in women as compared to men and increases with age. Around 2-5% of SCH patients are likely to progress to overt hypothyroidism every year.[5,6]
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