SCH treated by L-thyroxine leads to a significant improvement in CV risk factors and symptoms of tiredness. The CV risk factor reduction is related to the increased level of achieved free T(4) concentration.

SCH is associated with increased IHD (both prevalence and incidence) and cardiovascular mortality only in subjects from younger populations. These data suggest that increased vascular risk may only be present in younger individuals with SCH.

BACKGROUND Subclinical hypothyroidism (SCH) has been associated with ischemic heart disease (IHD); however, it is unknown whether treatment of SCH with levothyroxine sodium will reduce the risk of IHD. The aim of this study was to investigate the association between levothyroxine treatment of SCH with IHD morbidity and mortality. METHODS We used the United Kingdom General Practitioner Research Database to identify individuals with new SCH (serum thyrotropin levels of 5.01-10.0 mIU/L and normal free thyroxine levels) recorded during 2001 with outcomes analyzed until March 2009. All analyses were performed separately for younger (40-70 years) and older (>70 years) individuals. Hazard ratios (HRs) for IHD events (fatal and nonfatal) were calculated after adjustment for conventional IHD risk factors, baseline serum thyrotropin levels, and initiation of levothyroxine treatment as a time-dependent covariate. RESULTS Subclinical hypothyroidism was identified in 3093 younger and 1642 older individuals. For a median follow-up period of 7.6 years, 52.8% and 49.9% of younger and older patients with SCH were treated with levothyroxine, respectively. There were 68 incident IHD events in 1634 younger patients treated with levothyroxine (4.2%) vs 97 IHD events in 1459 untreated individuals (6.6%) (multivariate-adjusted HR, 0.61; 95% CI, 0.39-0.95). In contrast, in the older group there were 104 events in 819 treated patients (12.7%) vs 88 events in 823 untreated individuals (10.7%) (HR, 0.99; 95% CI, 0.59-1.33). CONCLUSIONS Treatment of SCH with levothyroxine was associated with fewer IHD events in younger individuals, but this was not evident in older people. An appropriately powered randomized controlled trial of levothyroxine in SCH examining vascular outcomes is now warranted.

GH deficiency is associated with increased cardiovascular morbidity, which may be determined by alterations in vascular risk factors. We report the effect of partially treated hypopituitarism and subsequent GH replacement (mean dose, 0.2 IU/kg.week) on putative cardiovascular risk factors in 22 nondiabetic hypopituitary subjects in a 6-month, double blind, controlled study (active/placebo ratio, 11:11). All patients were subsequently treated with GH for a further 6 months. Total fat, percent body fat, and central fat were measured by dual energy x-ray absorptiometry. The hypopituitary patients had increased percent fat (P = 0.03) and central fat (P < 0.01) compared with body mass index-matched controls. Before GH treatment, fasting (total) and specific insulin positively correlated with body mass index (P = 0.02 and P < 0.001, respectively), waist/hip ratio (P = 0.05 and P = 0.01), and central fat (P = 0.03 and P = 0.003). Specific insulin and insulin sensitivity (IS), calculated by homeostatic model of assessment, were related to total fat (P < 0.001 and P = 0.02). GH treatment for 6 months led to a reduction in total fat (P < 0.02), percent fat (P = 0.002), central fat (P = 0.012), waist/hip ratio (P < 0.05), total cholesterol (P = 0.03), and apolipoprotein-B (P = 00001), as well as a decrease in the IS from 36.9% (range, 12-100%) to 25% (range, 2.5-55%; P = 0.0002). This was paralleled by a rise in fasting (total) and specific insulin (P = 0.016 and P = 0.002). The degree of correlation among indices of IS, body composition, and fat distribution increased after GH treatment. Fasting plasma glucose rose significantly, but was within the reference range. During 12 months of GH therapy, a significant increase in serum lipoprotein-(a) was observed (P < 0.05). Although GH has beneficial effects on central adiposity and lipid fractions, it is also associated with a decrease in IS; these effects may vary between individuals.