Bone health and clinical results after hip fracture surgery in patients with subclinical hypothyroidism

Subclinical hypothyroidism is not associated with femoral osteoporosis in individuals aged 50 years or older

BACKGROUND

Thyroid dysfunction and osteoporosis are conditions strongly associated with aging, and the prevalence of both conditions is expected to increase in the coming decades. Thyroid hormones regulate bone metabolism, and the role of subclinical hypothyroidism on bone mineral density (BMD) is still controversial. Hence, this study aims to assess the association of subclinical hypothyroidism with femoral osteopenia and osteoporosis in individuals aged 50 years or older.

METHODOLOGY

This retrospective cohort study was carried out with 864 outpatients having at least one result for TSH levels before the first record of dual-energy X-ray absorptiometry (DXA). The primary endpoints were osteopenia (-2.5 standard deviation (SD) <T-score <-1.0SD) and osteoporosis (T-score ≤-2.5SD). Cox proportional hazards regression assessed the association of subclinical hypothyroidism (TSH ≥4.5 mIU/L) with osteopenia and osteoporosis in unadjusted and covariate-adjusted models. Hazard ratios (HR) and 95% confidence intervals (95%CI) were calculated, and p-values <0.05 were considered statistically significant.

RESULTS

There was no significant association between subclinical hypothyroidism and femoral osteopenia in either unadjusted [HR: 1.149 (0.835-1.580); p=0.394] or fully covariate-adjusted models [HR: 1.069 (0.774-1.477); p=0.687]. Subclinical hypothyroidism was associated with femoral osteoporosis in the unadjusted analysis [HR: 1.981 (1.044-3.757); p= 0.036], but a lack of association occurred and remained after successive covariate-adjustments analyses [HR: 1.392 (0.615-3.152); p=0.428].

CONCLUSION

Subclinical hypothyroidism is not independently associated with either femoral osteopenia or osteoporosis in individuals aged 50 years or older over a four-year follow-up time.

Negative Association of Subclinical Hypothyroidism on Improvement in Patient-Reported Outcomes After Total Knee Arthroplasty

BACKGROUND

The purpose of this study is to analyze the potential influence of subclinical hypothyroidism (SCH) on improvement in patient-reported outcome measures following primary total knee arthroplasty.

METHODS

A prospective, comparative cohort study between 92 SCH and 90 euthyroid patients was performed. Patients were followed up to 5 postoperative years. Patient-reported outcome measure was assessed by the Western Ontario and McMaster Universities Osteoarthritis Index questionnaire. The Knee Society Scores were used for functional evaluation, and 5-point Likert scale for patient satisfaction. The Hospital Anxiety and Depression scale was also used.

RESULTS

All outcome scores significantly improved from preoperative to final follow-up in both groups (P = .001). There were no significant differences between groups in Knee Society Scores (P = .057) at the final follow-up, but Western Ontario and McMaster Universities Osteoarthritis Index scores were significantly lower in the SCH group (P = .015). Likewise, the patient satisfaction rate was significant lower in the SCH group (0.010).

CONCLUSION

SCH patients have a slower functional recovery than euthyroid patients, and trended toward lower improvements in patient-reported scores. Depression was the most important negative factor. The findings of this study can provide the surgeon with an important information for better counseling the SCH patients.

The Influence of Thyroid Pathology on Osteoporosis and Fracture Risk: A Review

Thyroid hormones are important factors that regulate metabolism and cell differentiation throughout the human body. A complication of thyroid pathology is represented by an alteration of the bone metabolism which can lead to osteoporosis and fragility fractures, known to have a high mortality rate. Although there is a consensus on the negative impact of hyperthyroidism on bone metabolism, when referring to hypothyroidism, subclinical hypothyroidism, or subclinical hyperthyroidism, there is no general agreement. The aim of our review was to update clinicians and researchers about the current data regarding the bone health in hypothyroidism, subclinical hypothyroidism, and subclinical hyperthyroidism patients. Thyroid disorders have an important impact on bone metabolism and fracture risk, such that hyperthyroidism, hypothyroidism, and subclinical hyperthyroidism are associated with a decreased bone mineral density (BMD) and increased risk of fracture. Subclinical hypothyroidism, on the other hand, is not associated with osteoporosis or fragility fractures, and subclinical hyperthyroidism treatment with radioiodine could improve bone health.

Effect of subclinical hypothyroidism on the skeletal system and improvement with short-term thyroxine therapy

The purpose of the study was to observe changes in the skeletal system of rats with subclinical hypothyroidism (SCH) and to determine whether L-thyroxine (L-T4) administration suppresses those changes. Sixty male Wistar rats were randomly divided into control, SCH, and SCH+T4 groups. SCH was induced in rats by administration of methimazole (MMI), and rats in the SCH+T4 group were treated with L-T4 after 45 days of MMI administration. The SCH group had higher thyroid-stimulating hormone (TSH) level than the control and SCH+T4 groups. There were no differences in serum thyroid hormone (FT4 and FT3) levels among the three groups. Bone mineral density; serum levels of BALP and TRACP-5b, two bone metabolic markers; and the biomechanical properties of the femurs were lower in the SCH group than in the control group. After L-T4 treatment, serum BALP and TRACP-5b levels and the femur biomechanical properties were higher in the SCH+T4 than the SCH group. Histopathological examination revealed damage to the structure of the femur trabecular bone network in rats with SCH, and L-T4 treatment improved this condition to some extent. These findings demonstrate that L-T4 treatment ameliorates the destructive effects of SCH on the skeletal system in rats.

Thyrotropin serum levels are differentially associated with biochemical markers of bone turnover and stiffness in women and men: results from the SHIP cohorts

In two large German population-based cohorts, we showed positive associations between serum thyrotropin (TSH) concentrations and the Fracture Risk Assessment score (FRAX) in men and positive associations between TSH concentrations and bone turnover markers in women.

INTRODUCTION

The role of thyroid hormones on bone stiffness and turnover is poorly defined. Existing studies are confounded by differences in design and small sample size. We assessed the association between TSH serum concentrations and bone stiffness and turnover in the SHIP cohorts, which are two population-based cohorts from a region in Northern Germany comprising 2654 men and women and 3261 men and women, respectively.

METHODS

We calculated the bone stiffness index using quantitative ultrasound (QUS) at the calcaneus, employed FRAX score for assessment of major osteoporotic fractures, and measured bone turnover markers, N-terminal propeptide of type I procollagen (P1NP), bone-specific alkaline phosphatase (BAP), osteocalcin, and type I collagen cross-linked C-telopeptide (CTX) in all subjects and sclerostin in a representative subgroup.

RESULTS

There was no association between TSH concentrations and the stiffness index in both genders. In men, TSH correlated positively with the FRAX score both over the whole TSH range (p < 0.01) and within the reference TSH range (p < 0.01). There were positive associations between TSH concentrations and P1NP, BAP, osteocalcin, and CTX (p < 0.01) in women but not in men. There was no significant association between TSH and sclerostin levels.

CONCLUSIONS

TSH serum concentrations are associated with gender-specific changes in bone turnover and stiffness.