'Subclinical hypothyroidism'. Natural course of the syndrome during a prolonged follow-up study

146

Objective: The association between established hypothyroidism and high cholesterol levels is well known. The aim of the present study was to investigate the effect of thyroxine (T 4 ) administration on cholesterol levels in hypercholesterolemic subjects with TSH levels within the normal range ('highnormal' TSH compared with 'low-normal' TSH). Design and Methods: We determined TSH levels in 110 consecutive patients referred for hypercholesterolemia (serum cholesterol >7.5 mmol/l). Those with 'high-normal' TSH (2.0-4.0 mU/ml) as well as those with 'low-normal' TSH (0.40-1.99 mU/ml) were randomly assigned to receive either 25 or 50 mg T 4 daily for two months. Thus, groups A and B (low-normal TSH) received 25 and 50 mg T 4 respectively and groups C and D (high-normal TSH) received 25 and 50 mg T 4 respectively. Serum T 4 , tri-iodothyronine (T 3 ), TSH, free thyroxine index, resin T 3 uptake and thyroid autoantibodies (ThAab) as well as total cholesterol, high and low density lipoprotein cholesterol (HDL, LDL), and triglycerides were determined before and at the end of the two-month treatment period. Results: TSH levels were reduced in all groups. The most striking effect was observed in group D (TSH levels before: 2.77 Ϯ 0.55, after: 1.41 Ϯ 0.85 mU/ml, P < 0:01). Subjects in groups C and D had a higher probability of having positive ThAabs. A significant reduction in total cholesterol (P < 0:01) and LDL (P < 0:01) was observed after treatment only in group D. In those subjects in group D who were ThAab negative, there was no significant effect of thyroxine on cholesterol levels. Conclusions: Subjects with high-normal TSH levels combined with ThAabs may, in fact, have subclinical hypothyroidism presenting with elevated cholesterol levels. It is possible that these patients might benefit from thyroxine administration.

Section: Journal Of Endocrinology (1998) 138mentioning

confidence: 83%

High serum cholesterol levels in persons with 'high-normal' TSH levels: should one extend the definition of subclinical hypothyroidism?

Michalopoulou¹,

Alevizaki²,

Piperingos³

et al. 1998

146

“…With respect to the previous studies on young (3)(4)(5)(6)(7) or old patients (11)(12)(13)(14), our study design is peculiar, in that we have preliminarily excluded all the underlying diseases and the risk factors that are known to be able to affect the natural course of SH (3-7). According to our results, the natural history of TSH serum levels in a pediatric population with idiopathic SH is characterized by their progressive decrease over time, with no concomitant changes in FT 4 values.…”

Section: Discussionmentioning

confidence: 99%

Prospective evaluation of the natural course of idiopathic subclinical hypothyroidism in childhood and adolescence

Wasniewska¹,

Salerno²,

Cassio³

et al. 2009

108

109

Objective: To prospectively evaluate the course of subclinical hypothyroidism (SH) in children and adolescents with no underlying diseases and no risk factors, which might interfere with the progression of SH. Design: Clinical status, thyroid function, and autoimmunity were prospectively evaluated at entry and after 6, 12, and 24 months in 92 young patients (mean age 8.1G3.0 years) with idiopathic SH. Results: During the study, mean TSH levels showed a trend toward a progressive decrease while FT 4 levels remained unchanged. Overall, 38 patients normalized their TSH (group A): 16 patients between 6 and 12 months, and 22 patients between 12 and 24 months. Among the remaining 54 patients, the majority maintained TSH within the baseline values (group B), whereas 11 exhibited a further increase in TSH above 10 mU/l (group C). Baseline TSH and FT 4 levels were similar in the patients who normalized TSH, compared with those with persistent hyperthyrotropinemia. Even in the patients of group C, both TSH and FT 4 at entry were not different with respect to those of groups A and B. No patients showed any symptoms of hypothyroidism during follow-up and no changes in both height and body mass index were observed throughout the observation period. Conclusions: (a) The natural course of TSH values in a pediatric population with idiopathic SH is characterized by a progressive decrease over time; (b) the majority of patients (88%) normalized or maintained unchanged their TSH; and (c) TSH changes were not associated with either FT 4 values or clinical status or auxological parameters.

“…Several investigations have carried out follow-up studies on patients with SH (10,(22)(23)(24)(25)(26), but none of these studies used as short and regular control intervals as the present study. Four-year follow-up of SH patients from the Wickham study showed that 8 out of 48 developed OH.…”

Section: Discussionmentioning

confidence: 99%

Serum TSH and serum thyroid peroxidase antibody fluctuate in parallel and high urinary iodine excretion predicts subsequent thyroid failure in a 1-year study of patients with untreated subclinical hypothyroidism

Karmisholt

Laurberg²

2008

Objective: To explore the possibility of predicting decline or improvement in thyroid function over 1 year, and to investigate the correlations of serum TSH (s-TSH) with hypothyroidism-related symptoms and signs, serum thyroid peroxidase antibody (s-TPO-Ab) and urinary iodine excretion in individual patients with untreated subclinical hypothyroidism (SH). Design: Monthly repeated measurement study without intervention. Methods: Twenty-one patients without former thyroid disease who had been identified with s-TSH between 5 and 12 mU/l and normal serum thyroxine (s-T 4 ) at two occasions were enrolled. Subsequently, 13 monthly measurements of s-TSH, hypothyroidism-related symptoms and signs, serum free T 4 , s-TPO-Ab and urinary iodine excretion were performed. Results: Over the study year, s-TSH increased significantly in 5 patients, 16 had unchanged s-TSH, whereas none improved. From clinical and biochemical inclusion data, it was not possible to predict who would later increase in s-TSH. In individual patients, a highly significant correlation between s-TSH and s-TPO-Ab was found (rZ0.37, P!0.0001) and also between s-TSH and urinary iodine excretion (rZ 0.14, PZ0.034). No correlation between s-TSH and clinical symptoms and signs was observed. Time shift showed best correlation between s-TSH and s-TPO-Ab measured at the same time point, whereas urinary iodine excretion correlated best to s-TSH and s-TPO-Ab obtained 1 month later. Conclusion: At the time of inclusion, it was not possible to identify the 24% of SH patients who would show deterioration in thyroid function over the following year. Impairment in thyroid function varied in parallel with thyroid autoimmunity, whereas high urinary iodine excretion predicted high s-TSH and s-TPO-Ab 1 month later.