INTRODUCTIONSubclinical hyperthyroidism (SH, grade 1, thyrotropin (TSH) ≥0.1 mU/L and grade 2, TSH <0.1 mU/L) is a common disorder with increased prevalence in older subjects. There is evidence for increased morbidities in SH, such as atrial fibrillation and osteoporosis. We aim to study the natural history and comorbidities of SH from patients referred to a tertiary endocrine clinic in Singapore as they are currently unknown.

MATERIALS AND METHODSRetrospective evaluation of SH subjects for natural progression and comorbidities.

RESULTSOne hundred and thirteen SH subjects (male/female: 24/89, mean age: 67.2 years, grade 1/grade 2: 60/53) were identified from the endocrine clinic. The aetiology of SH include 52 multinodular goitre, 15 Graves' disease, 7 toxic adenoma and 39 unclassified. A minority of SH patients (5.3 %) progressed to overt hyperthyroidism while 13% remitted to euthyroid state (1 to 3 years with a mean follow-up of 18 months) in the total cohort. Most of the patients remained in SH state during follow-up (50/60 in grade 1 SH and 42/53 in grade SH). However, no single predictive factor could be identified for progression or remission of SH. The prevalence of morbidities in SH subjects include ischaemic heart disease (16.8%), heart failure (8.9%), tachyarrhythmias (13.3%), any cardiovascular disease (28%), cerebrovascular disease (28%), osteoporosis (28%), and any fracture (15.9%).

CONCLUSIONMost of SH cases in our cohort remain in subclinical state with very few progressing to overt hyperthyroidism. Significant proportion of SH subjects have vascular disease, but this association needs to be confirmed in prospective controlled studies.

Aged ; Disease Progression ; Female ; Humans ; Hyperthyroidism ; complications ; diagnosis ; Male ; Prospective Studies ; Tertiary Care Centers

INTRODUCTION: The impact of noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) on the risk of malignancy (ROM) in fine-needle aspiration cytology (FNAC) per The Bethesda System for Reporting Thyroid Cytopathology has not been well reported in Singapore. METHODS: We retrospectively identified 821 thyroid nodules with preoperative FNAC from 788 patients out of 1,279 consecutive thyroidectomies performed between January 2010 and August 2016 in a tertiary general hospital in Singapore. Possible cases of NIFTP were reviewed for reclassification and the impact of NIFTP on ROM was analysed. RESULTS: The incidence of NIFTP was 1.2% (10 out of 821). If NIFTP is considered benign, ROM in Bethesda I through VI were 8.6%, 3.5%, 26.3%, 20.0%, 87.7%, 97.0% versus 8.6%, 4.2%, 28.1%, 26.7%, 89.2% and 100% if NIFTP is considered malignant. Eight patients with NIFTP had follow-up of 15 to 110 months. One had possible rib metastasis as evidenced by I131 uptake but remained free of structural or biochemical disease during a follow-up period of 110 months. None had lymph node metastasis at presentation, nor locoregional or distant recurrence. CONCLUSION Classifying NIFTP as benign decreased ROM in Bethesda II through VI, but the benignity of NIFTP requires more prospective studies to ascertain. The impact of NIFTP on ROM in our institution also appears to be lower than that reported in the Western studies.
Adenocarcinoma, Follicular/epidemiology* ; Humans ; Prospective Studies ; Retrospective Studies ; Singapore/epidemiology* ; Thyroid Neoplasms/epidemiology*