The Management of Thyroid Abnormalities in Chronic Heart Failure

Risks of suboptimal and excessive thyroid hormone replacement across ages

BACKGROUND

Hypothyroidism is prevalent at all ages and represents a non-communicable disease with preventable consequences.

METHOD

Narrative review.

REVIEW

In children and adolescents, the most devastating consequences of undertreatment with levothyroxine (LT4) are poor growth and development. Delayed treatment in congenital hypothyroidism can lead to permanent brain damage. In young to middle-aged adults, symptoms are often overlooked, and treatment delayed by many years. The resulting consequences are also at this age group compromised brain and physical function but less severe and partly reversible with treatment. The under-treated condition often results in a higher risk of, e.g., increased cardiovascular disease burden, obesity, hypertension, poor physical capacity, and poor quality of life. Excessive replacement is at all adult age groups associated with increased risk of cardiac death, osteoporosis, loss of muscle function, psychological instability and poor quality of life. In young fertile women, the consequences of undertreatment with LT4 are subnormal fertility, recurrent pregnancy loss, compromised fetal growth, and neurocognitive development. On the other hand, excessive LT4 treatment has been related to gestational hypertension, preeclampsia and preterm birth. In the elderly, care must be given to avoid confusing a slightly high age-related serum TSH with requirement for LT4 treatment in a truly hypothyroid patient. Excessive LT4 treatment in patients of high age is associated with an increased mortality.

CONCLUSION

Suboptimal and excessive LT4 replacement of the preventable non-communicable disease hypothyroidism requires more focus from the healthcare system and from the global political systems to prevent the personally devastating and socioeconomically challenging consequences.

Consequences of undertreatment of hypothyroidism

PURPOSE

To provide an overview of consequences of undertreatment with levothyroxine (LT4) in the common non-communicable disease, hypothyroidism.

METHODS

Narrative review of the literature.

RESULTS

Hypothyroidism is globally very prevalent at all age groups and represents a non-communicable disease in which the risks and consequences are preventable. In children and adolescents, the most devastating consequences of undertreatment are poor growth and development. Lack of early treatment in congenital hypothyroidism can lead to permanent damage of brain function. In young to middle-aged adults, consequences are often overlooked, and treatment delayed by many years. The resulting consequences are also at this age group compromised brain and physical functioning but less severe and partly reversible with treatment. The undertreated condition often results in a higher risk of several secondary devastating diseases such as increased cardiovascular disease burden, obesity, hypertension, poor physical capacity, poor quality of life. In young women of fertile age the consequences of undertreatment with LT4 are subnormal fertility, recurrent pregnancy loss, preeclampsia, compromised fetal growth and neurocognitive development. There is a further risk of 30-50% of developing postpartum thyroiditis. In the elderly population care must be given to avoid confusing a slightly high serum TSH as result of physiological age adaptation with a requirement for LT4 treatment in a truly hypothyroid patient.

CONCLUSION

Undertreatment of the preventable non-communicable disease hypothyroidism requires more focus both from caretakers in the healthcare system, but also from the global political systems in order to prevent the personally devastating and socioeconomically challenging consequences.

Non-thyroidal disease syndrome in patients with systemic lupus erythematosus: relation to disease inflammatory activity

OBJECTIVE

To identify risk factors for the development of non-thyroidal illness syndrome (NTIS) in patients with systemic lupus erythematosus (SLE).

METHODS

A retrospective analysis of 517 SLE patients and 1034 age-and sex-matched healthy population was conducted to compare the prevalence of NTIS in these two groups, and to analyze the laboratory and clinical characteristics of SLE patients with NTIS. Finally Logistic regression analysis was used to determine the risk factors for NTIS in SLE patients.

RESULTS

The prevalence of NTIS in the SLE patients was significantly higher than that in controls (39.7% vs. 1.0%, P < 0.001). In SLE patients, compared with euthyroidism patients, NTIS patients exhibited higher levels of neutrophils, hepatic enzymes, kidney damage markers, inflammatory markers and SLE disease activity index (SLEDAI). They also had a higher incidence of organ insufficiency and positive antibodies such as anti-ds-DNA antibodies and anti-SSA antibodies. However, NTIS patients had lower levels of hemoglobin, lymphocytes, platelets, serum albumin, and complement. Additionally, NTIS patients had a shorter duration of lupus and lower utilization of disease-modifying antirheumatic drugs (DMARDs) (P < 0.05). Logistic regression analysis showed that elevated SLEDAI (OR = 1.060, 95%CI 1.022-1.099, P = 0.002), elevated systemic immune-inflammation index (SII) (OR = 1.003, 95%CI 1.001-1.007, P = 0.026), elevated erythrocyte sedimentation rate (ESR) (OR = 1.019, 95%CI 1.010-1.028, P < 0.001), and hepatic insufficiency (OR = 1.916, 95% CI 1.173-3.131, P = 0.009) were independent risk factors for the development of NTIS in SLE. DMARDs treatment (OR = 0.495, 95% CI 0.306-0.799, P < 0.001) was an independent protective factor for NTIS.

CONCLUSIONS

Inflammatory activity in SLE patients is associated with the development of NTIS. Key Points • Inflammatory activity indexes such as SLEDAI, SII, and ESR are independent risk factors for NTIS in SLE patients.

Triiodothyronine alongside levothyroxine in the management of hypothyroidism?

The current guideline-based management of hypothyroidism recommends monotherapy with levothyroxine (LT4), titrated to maintain the level of thyrotropin within a euthyroid reference range. This has been successful for most people with hypothyroidism, but a substantial minority still report symptoms of hypothyroidism unexplained by a comorbid medical condition. LT4 is essentially a prodrug for triiodothyronine (T3), the thyroid hormone that acts on target tissues in the brain and the periphery. Thyroid hormone replacement with LT4 alone does not restore physiological tissue levels of thyroid hormones, particularly T3. During the last two decades, much interest has focussed on the potential of combinations of LT4 and T3 to provide a superior outcome to LT4 monotherapy for people with hypothyroidism, especially those with residual symptoms despite thyrotropin-optimized LT4. This review seeks to provide an overview of currently available evidence on combination (LT4 + T3) therapy to be used for personalized medicine in patients with hypothyroidism. A number of randomized, controlled trials (RCTs) have failed to demonstrate superiority for the combination therapy approach, largely due to non-physiological T3 doses. However, patients with hypothyroidism are highly heterogeneous in terms of their residual thyroid function, individual set points for optimal thyroid homeostasis and for the presence or absence of polymorphisms in deiodinase enzymes in tissues that activate and deactivate circulating thyroid hormones. Accordingly, these RCTs may have failed to demonstrate benefits of combination therapy in individual hypothyroid phenotypes. The pharmacokinetics of LT4 and T3 also differ, which is a barrier to their co-administration. Future clinical trials using LT4 + T3 tablets better suited for combination therapy will resolve the outstanding research questions relating to the place of LT4 + T3 combination therapy in the management of hypothyroidism.

Levothyroxine Therapy in Elderly Patients With Hypothyroidism

Levothyroxine (L-T4) treatment of overt hypothyroidism can be more challenging in elderly compared to young patients. The elderly population is growing, and increasing incidence and prevalence of hypothyroidism with age are observed globally. Elderly people have more comorbidities compared to young patients, complicating correct diagnosis and management of hypothyroidism. Most importantly, cardiovascular complications compromise the usual start dosage and upward titration of L-T4 due to higher risk of decompensating cardiac ischemia and -function. It therefore takes more effort and care from the clinician, and the maintenance dose may have to be lower in order to avoid a cardiac incidence. On the other hand, L-T4 has a beneficial effect on cardiac function by increasing performance. The clinical challenge should not prevent treating with L-T4 should the patient develop e.g., cardiac ischemia. The endocrinologist is obliged to collaborate with the cardiologist on prophylactic cardiac measures by invasive cardiac surgery or medical therapy against cardiac ischemic angina. This usually allows subsequent successful treatment. Management of mild (subclinical) hypothyroidism is even more complex. Prevalent comorbidities in the elderly complicate correct diagnosis, since many concomitant morbidities can result in non-thyroidal illness, resembling mild hypothyroidism both clinically and biochemically. The diagnosis is further complicated as methods for measuring thyroid function (thyrotropin and thyroxine) vary immensely according to methodology and background population. It is thus imperative to ensure a correct diagnosis by etiology (e.g., autoimmunity) before deciding to treat. Even then, there is controversy regarding whether or not treatment of such mild forms of hypothyroidism in elderly will improve mortality, morbidity, and quality of life. This should be studied in large cohorts of patients in long-term placebo-controlled trials with clinically relevant outcomes. Other cases of hypothyroidism, e.g., medications, iodine overload or hypothalamus-pituitary-hypothyroidism, each pose specific challenges to management of hypothyroidism; these cases are also more frequent in the elderly. Finally, adherence to treatment is generally challenging. This is also the case in elderly patients, which may necessitate measuring thyroid hormones at individually tailored intervals, which is important to avoid over-treatment with increased risk of cardiac morbidity and mortality, osteoporosis, cognitive dysfunction, and muscle deficiency.

Thyroid hormone therapy for subclinical hypothyroidism

Subclinical Hypothyroidism (SCH) is defined as a raised level of serum TSH level in the presence of normal circulating free thyroid hormones. SCH is a highly prevalent condition displaying some peculiarities, both in terms of the diagnostic and therapeutic approach, when specific population and/or concomitant diseases are taken into account. The debate upon whether LT4 therapy should be initiated or not in patients with SCH is a long lasting one and still it remains controversial. Current evidence supports the concept that the clinical consequences of SCH may be profoundly different in relation to several patient-specific characteristics. Aim of the present review is to provide updated indications for SCH treatment in specific clinical settings. These will include the management of SCH in obese and diabetic patients, in pregnant women, and in specific age groups. Treatment modalities, including LT4 doses and recommended follow-up strategy will also be discussed. In the era of "precision medicine" the decision to-treat-not-to-treat SCH should be individualized taking into account risks and beneficial outcomes of LT4 therapy. With this in mind, we reviewed the most relevant studies in the recent literature in order to provide evidence for or against LT4 replacement therapy for SCH in specific clinical settings.

Hypothyroidism: Cardiovascular Endpoints of Thyroid Hormone Replacement

Thyroid dysfunction, either thyrotoxicosis or hypothyroidism, represents an important cardiovascular risk factor. Heart disease is the leading cause of death for men and women in the United States. Cardiovascular disease is multifactorial and many efforts have been made to assess precipitants for optimal guideline-based, primary, and secondary prevention. Thyroid hormone receptors are present in the myocardium and endothelium, and small alterations in its levels could have significant effects in cardiac function. Specifically, overt hypothyroidism is associated with an increased risk for atherosclerotic cardiovascular disease due to metabolic and hemodynamic effects. Several concomitant factors like impaired lipid profile, low-grade chronic inflammatory state, increased oxidative stress and increased insulin resistance enforce this relationship. The last decade has seen a renewed interest on the impact of subclinical hypothyroidism on the cardiovascular system and whether or not it should be treated. The aim of this review is to provide current evidence of the effect of thyroid hormone replacement, either with levothyroxine mono-therapy or in combination with liothyronine, on specific cardiovascular parameters.