Thyroid hormones in children with epilepsy during long-term administration of carbamazepine and valproate

Analysis of the action mechanisms and targets of herbal anticonvulsants highlights opportunities for therapeutic engagement with refractory epilepsy

Epilepsy is a neurological disorder characterized by spontaneous and recurring seizures. It poses significant therapeutic challenges due to diverse etiology, pathobiology, and pharmacotherapy-resistant variants. The anticonvulsive effects of herbal leads with biocompatibility and toxicity considerations have attracted much interest, inspiring mechanistic analysis with the view of their use for engagement of new targets and combination with antiseizure pharmacotherapies. This article presents a comprehensive overview of the key molecular players and putative action mechanisms of the most common antiepileptic herbals demonstrated in tissue culture and preclinical models. From the review of the literature, it emerges that their effects are mediated via five distinct mechanisms: (1) reduction of membrane excitability through inhibition of cation channels, (2) improvement of mitochondrial functions with antioxidant effects, (3) enhancement in synaptic transmission mediated by GABAA receptors, (4) improvement of immune response with anti-inflammatory action, and (5) suppression of protein synthesis and metabolism. While some of the primary targets and action mechanisms of herbal anticonvulsants (1, 3) are shared with antiseizure pharmacotherapies, herbal leads also engage with distinct mechanisms (2, 4, and 5), suggesting new drug targets and opportunities for their integration with antiseizure medications. Addressing outstanding questions through research and in silico modeling should facilitate the future use of herbals as auxiliary therapy in epilepsy and guide the development of treatment of pharmacoresistant seizures through rigorous trials and regulatory approval.

Hormonal Changes in Women with Epilepsy

Epilepsy is a prevalent neurological disorder among women globally, often requiring long-term treatment. Hormonal fluctuations in women with epilepsy (WWE) can have reciprocal effects on epilepsy and antiseizure medications (ASMs), posing significant challenges for WWE. Notably, WWE commonly experience endocrine alterations such as thyroid dysfunctions, low bone metabolism, and reproductive hormone irregularities. On the one hand, the presence of hormones in women with epilepsy affects their susceptibility to epilepsy as well as the metabolism of antiseizure medications in various ways. On the other hand, epilepsy itself and the use of antiseizure medications impact the production, secretion, and metabolism of hormones, resulting in low fertility, increased risk of pregnancy complications, negative offspring outcomes, and so on. In order to develop more precise treatment strategies in the future, it is necessary to comprehend the explicit relationships between hormones, epilepsy, and antiseizure medications, as well as to elucidate the currently known mechanisms underlying these interactions.

Thyroid functions as a parameter in monitoring of antiepileptic drugs

INTRODUCTION

Epilepsy is a chronic neurological disorder that is treated with multiple medications that can have significant side effects. This study investigated the potential effects of antiepileptic drugs on thyroid function.

METHODS

The participants in this study were epileptic adults who had been consistently monitored in follow-up care. The effects of antiepileptic drugs on the serum levels of the thyroid stimulating hormone (TSH), free T3 (fT3), and free T4 (fT4) of these patients were investigated retrospectively by comparing laboratory recordings in three defined periods: prior to antiepileptic drug treatment, between 6 months and 1 year of treatment (early stage), and after 1 year of treatment (late stage).

RESULTS

  A total of 300 epileptic patients (F/M: 175/125) were included in the study. Significant differences in TSH and fT4 serum levels in the late stage compared to the pre-treatment stage (p = 0.006 and p = 0.0005, respectively) were found. TSH values in the late stage of treatment were abnormally high in one case and low in five cases; all six of these cases had normal pre-treatment and early-stage TSH values. Patients who received monotherapy with valproic acid, levetiracetam or carbamazepine were evaluated separately and there was no statistically significant difference in TSH and fT3 levels, while fT4 levels were significantly increased during treatment in each treatment group.

CONCLUSIONS

A significant increase in TSH levels was found in epileptic patients on polytherapy. Our results give us the opportunity to highlight the potential unique or cumulative effect of antiepileptic drugs on thyroid hormone levels.

Is the prevalence of thyroid disease higher in children receiving antiepileptic medication? A systematic review and meta-analysis

PURPOSE

Antiseizure medications (ASM) have long been examined for their potential to induce thyroid dysfunction. The aim of this systematic review and meta-analysis was to assess the prevalence of thyroid disease in children up to 16 years receiving monotherapy with valproate (VPA), carbamazepine (CBZ) and levetiracetam (LEV).

METHODS

PubMed/MEDLINE, Cochrane/CENTRAL databases and the gray literature were searched to identify observational studies providing the prevalence of thyroid dysfunction in the target population under VPA, CBZ, or LEV monotherapy schemes. The results were pooled using a random-effects model, and additional subgroup analyses were performed for the three ASM groups.

RESULTS

Fifteen and thirteen studies met inclusion criteria for the qualitative and the quantitative analysis, respectively, with a total of 945 pediatric patients with prevalence data. Only VPA and CBZ were associated with thyroid dysfunction. The overall prevalence of thyroid abnormality was higher in children receiving ASM [odds ratio (OR) 6.82, 95% confidence interval (CI) 3.96-11.75]. In the subgroup analysis, the prevalence of biochemical thyroid abnormality with increased TSH was higher in the VPA (OR 9.54, 95%CI 5.25-17.34) and the CBZ group (OR 4.08, 95%CI 1.84-9.04) compared with controls.

CONCLUSION

This study confirms the higher prevalence of biochemical thyroid abnormality in children under VPA and CBZ monotherapy, whereas no such evidence is present for LEV. In children with a predisposition for thyroid disease, LEV should be considered over VPA and CBZ, if appropriate for seizure type and epilepsy syndrome. More studies are needed to reach a consensus on monitoring and management of thyroid dysfunction in children receiving ASM therapy.

Antiseizure medications and thyroid hormone homeostasis: Literature review and practical guideline

Thyroid hormones play an essential role in central nervous system development, normal physiological brain function, and repair mechanisms. On one hand, thyroid hormone alterations influence cortical excitability, and on the other hand antiseizure medications (ASMs) are associated with alterations in thyroid hormone metabolism. Although this interaction has long been described, and epilepsy is a common and chronic neurological disease, studies describing the interplay are often small and retrospective. We performed a systematic review of the current literature on epilepsy, ASMs, and thyroid hormone metabolism. Forty-seven studies were included. Most studies were retrospective cross-sectional studies (n = 25) and investigated thyroid function alterations in patients on older ASMs such as phenobarbital, phenytoin, carbamazepine, and valproate. Overall, almost one third of patients with epilepsy had thyroid hormone alterations, especially patients on valproate (25%) and carbamazepine (10%-25%). Studies with patients receiving polytherapy are scarce, but reported a higher risk for hypothyroidism in patients with older age (p = .004), female sex (p = .014), longer duration of epilepsy (p = .001), intractable epilepsy (p = .009), and polytherapy. Studies on newer ASMs are also limited, and further studies on an interplay with thyroid hormone homeostasis are essential to improve the care for epilepsy patients. ASMs are associated with alterations in thyroid hormone metabolism. Thyroid function monitoring is indicated in patients on ASMs, especially those with refractory epilepsy and those on polytherapy. We provide a practical guideline for thyroid function monitoring for the clinician taking care of patients on ASMs.

Thyroid Functions in Children on Levetiracetam or Valproic Acid Therapy

The aim of this study was to investigate the thyroid functions in children receiving levetiracetam or valproate monotherapy. We retrospectively reviewed the records of children with controlled epilepsy receiving valproic acid (VPA group) or levetiracetam monotherapy (LEV group) for at least 6 months. Free thyroxine 4 levels (fT4) and thyroid stimulating hormone (TSH) levels were compared between VPA group, LEV group, and age- and gender-matched healthy children (control group). A total of 190 children were included in the study: 63 were in the VPA, 60 in the LEV, and 67 in the control group. Although there was no significant difference regarding average fT4 levels, higher TSH levels were found in the VPA group when compared with the LEV and control groups (p < 0.001 and p < 0.001, respectively). There was no significant difference in terms of fT4 and TSH values in the LEV group when compared with the control group (p = 0.56 and p = 0.61, respectively). Subclinical hypothyroidism (defined as a TSH level above 5 uIU/mL with a normal fT4 level was detected in 16% of patients in the VPA group, none in the LEV and control groups. Our study found that VPA therapy is associated with an increased risk of subclinical hypothyroidism while LEV had no effect on thyroid function tests.

The effect of antiepileptic drugs on thyroid hormonal function: valproic acid and phenobarbital

The aim of this study was to evaluate the thyroid function alterations in a group of epileptic children taking antiepileptic drugs. The study included a total of 183 pediatric epilepsy patients, aged 15 months-16 years, comprising 114 patients treated with valproic acid, 69 patients treated with phenobarbital, and 151 age-matched healthy volunteers as the control group. Serum levels of thyroid hormones were measured before the beginning of the antiepileptic therapy and after 12 months of treatment. Thyroid-stimulating hormone levels were significantly higher in the 12th month of phenobarbital and valproic acid treatment. The level of free triiodothyronine before treatment was higher in epileptic patients than in the control group. Subclinical hypothyroidism at month 12 was determined in 15.2% of the valproic acid group and in 2.9% of the phenobarbital group. When compared with the pre-treatment values, there was a statistically significant difference in the incidence of subclinical hypothyroid in the valproic acid group and no significant difference in the phenobarbital group. Symptomatic hypothyroidism was not detected. It was concluded that the thyroid functions of patients using valproic acid and phenobarbital for a long time should be regularly monitored.

Effect of levetiracetam monotherapy on lipid profiles and thyroid hormones in children with epilepsy: A prospective study

Long-term treatment with some older antiepileptic drugs may lead to dyslipidemia or thyroid disturbances. The effect of levetiracetam (LEV), a newer broad spectrum antiepileptic agent, on cardiovascular risk factors is not yet sufficiently investigated. The purpose of this study was to investigate prospectively the effect of LEV monotherapy on serum lipid profile and thyroid hormones levels in children with epilepsy. The study population consisted of 39 children (21 females, 18 males, mean age 6.8 ± 4,1 years, range 2-15 years) that were treated for new-onset epilepsy with LEV monotherapy. Serum total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), triglycerides (TGs), apolipoprotein A-I (apo A-I), apolipoprotein B (apo B), lipoprotein (a) [Lp(a)], thyroxine (T4), free thyroxine (FT4) and thyrotropin (TSH), were evaluated before and at 6 and 12 (n = 28) months of LEV monotherapy. TGs were significantly decreased at 6 and 12 months of LEV treatment (p = 0.026 and p = 0.001, respectively). TGs/HDL-C ratio was significantly decreased at 6 and 12 months of LEV treatment (p = 0.024 and p = 0.003, respectively), while LDL-C/HDL-C ratio was significantly decreased at 12 months of LEV treatment (p = 0.025). There were no significant alterations in the other parameters during the study. In conclusion, long-term LEV monotherapy does not cause adverse alterations on thyroid hormones and serum lipids in children with epilepsy. More studies are needed to clarify whether LEV monotherapy have a favourable effect on serum lipids and whether LEV may be considered as a safer alternative drug for the prevention of antiepileptic drug-induced cardiovascular complications in adult life.

Antiepileptic drugs are associated with central hypothyroidism

OBJECTIVE

Studies in children have shown an increased frequency of central hypothyroidism (CH) with long-term use of antiepileptic drugs (AEDs). The aim of this study was to search for CH in adults treated with AEDs and find whether the type of AEDs used matters.

MATERIALS AND METHODS

Adult epileptic patients treated at the neurology outpatient clinic at Landspitali University Hospital (LSH) from 1998 to 2011 were included. Patients were invited for a blood test if serum levels for TSH (s-TSH) or free-T₄ (s-fT₄ ) had not already been obtained. CH was defined as s-fT₄ below the reference range (12-22 pmol/L) and normal s-TSH levels (0.30-4.20 mIU/L). Data were analyzed using logistic regression and Mann-Whitney test.

RESULTS

We identified 165 patients (92 women), mean age 45.6 (±15.5, range: 20-92) years. The mean s-fT₄ -level in our group was 14.2 (±2.9, range: 8.1-24.4) pmol/L compared with 16.9 (±6.1) pmol/L in a sample of 13248 measurements at LSH during one year (LSH-group) (P < 0.001). The difference in s-fT₄ -level between men and the LSH-group was significant and also for women (P < 0.001 and P < 0.001, respectively). Thirty-five patients (21%) had CH. A significant association with the use of carbamazepine or oxcarbazepine was found, odds ratio for women 15.0 (95% CI: 4.6-49.5) and 1.8 (95% CI: 0.4-8.3) for men.

CONCLUSION

21% of patients treated with AEDs had CH, more often patients taking carbamazepine or oxacarbazepine, and more often women. The s-fT₄ -level was lower among patients treated with AEDs.

Lipid and thyroid hormone levels in children with epilepsy treated with levetiracetam or carbamazepine: A prospective observational study

Although previous studies have investigated the influence of antiepileptic drugs (AEDs) on lipid profiles and thyroid hormone levels, there is little evidence regarding the effects of levetiracetam (LEV). Therefore, we conducted a prospective longitudinal study to evaluate the effects of LEV and carbamazepine (CBZ) treatment on lipid profile and thyroid hormone levels in patients newly diagnosed with epilepsy. Inclusion criteria were as follows: (a) age between 4 and 15 years, (b) diagnosis of epilepsy with at least two focal seizures within a year, and (c) newly treated with LEV or CBZ monotherapy. Serum lipid profile and thyroid hormone levels were measured before and after 1 and 6 months of AED initiation. Among the 21 included patients (LEV: 13 patients, CBZ: 8 patients), all but one patient in the LEV group continued AED monotherapy during the study period. Although triglyceride (TG) levels tended to be increased in the CBZ group (baseline: 58.3 ± 22.0 mg/dl, 1 month: 63.8 ± 21.6 mg/dl, 6 months: 92.3 ± 63.6 mg/dl, p = 0.22, analyses of variance (ANOVA)), there were no significant changes in total cholesterol (TC), TG levels, high-density lipoprotein cholesterol (HDL-C), or low-density lipoprotein cholesterol (LDL-C) in either group. Serum free thyroxine (fT4) levels were significantly decreased in the CBZ group (baseline: 1.15 ± 0.06 ng/dl, 1 month: 1.00 ± 0.16 ng/dl, 6 months: 0.98 ± 0.14 ng/dl, p = 0.03, ANOVA). In contrast, there were no significant changes in fT4 or thyroid-stimulating hormone (TSH) levels in the LEV group. The results of the present study suggest that LEV monotherapy does not affect lipid profile or thyroid function while CBZ monotherapy may cause thyroid dysfunction.

Maternal carbamazepine alters fetal neuroendocrine-cytokines axis

This study detected the impact of maternal carbamazepine (CBZ) on the fetal neuroendocrine-cytokines axis. 25 or 50mg/kg of CBZ was intraperitoneally administrated to pregnant albino rats from the gestation day (GD) 1 to 20. Both administrations of CBZ caused a hypothyroidism in dams and fetuses whereas the decreases in serum thyroxine (T4) and triiodothyronine (T3) and increases in serum thyrotropin (TSH) levels were highly significant (LSD; P <0.01) at GD 20 compared to untreated control dams. Also, both administrations had undesirable impacts on the maternofetal body weight, litter weight, survival of dams and fetuses, and their food consumption in comparison to the corresponding control. These administrations also elicited a reduction in fetal serum growth hormone (GH), interferon-γ (IFNγ), interleukins (IL-2 & 4) and prostaglandin E2 (PGE2) levels. Also, the elevation in fetal serum tumor necrosis factor-alpha (TNFα), transforming growth factor-beta (TGFβ), and interleukins (IL-1β & 17) levels was observed at embryonic day (ED) 20. Moreover, there were a cellular fragmentation, distortion, hyperemia, oedema and vacuolation in the fetal cerebellar cortex due to both maternal administrations. These developmental changes were dose-dependent. These novel results suggest that CBZ may act as a developmental immunoneuroendocrine disruptor.

Association of antiepileptic drug usage, trace elements and thyroid hormone status

BACKGROUND

Levels of thyroid hormone (TH) and trace elements (copper (Cu) and selenium (Se)) are important for development and function of the brain. Anti-epileptic drugs (AEDs) can influence serum TH and trace element levels. As the relationship between AEDs, THs, and trace elements has not yet been studied directly, we explored these interactions.

METHOD

In total 898 participants, from the Thyroid Origin of Psychomotor Retardation study designed to investigate thyroid parameters in subjects with intellectual disability (ID), had data available on serum Se, Cu, thyroid stimulating hormone (TSH), free thyroxine (FT4), tri-iodothyronine (T3), reverse T3, T4, and thyroxine-binding globulin (TBG); 401 subjects were on AED treatment. Differences in trace elements according to medication usage was investigated using ANOVA, and associations between trace elements and thyroid parameters were analysed using (non-) linear regression models.

RESULTS

Study participants were not deficient in any of the trace elements analyzed. AED (carbamazepine, valproate and phenytoin) usage was negatively associated with serum Se and showed compound-specific associations with Cu levels. After correction for drug usage, Se was positively associated with TSH levels, negatively associated with FT4 levels, and positively with T3 levels. Cu was positively associated with T4, T3, and rT3, which was largely dependent on TBG levels.

CONCLUSION

The subjects with ID did not display profound deficiencies in trace element levels. AEDs were associated with serum Se and Cu levels, while serum Se and Cu were also associated with thyroid parameters. Further studies on the underlying mechanisms and potential clinical importance are warranted.

Endocrine Effects of Valproate versus Carbamazepine in Males with Epilepsy: A Prospective Study

BACKGROUND/AIMS

To prospectively evaluate the long-term impact of valproate (VPA) versus carbamazepine (CBZ) on anthropometric, hormonal, and metabolic parameters in young male patients treated for epilepsy.

METHODS

Of 61 boys with newly diagnosed epilepsy followed up, 24 were excluded from analysis (17 were lost to follow-up and 7 changed therapy within <1 year). Findings were compared by time, treatment (VPA or CBZ), and epilepsy type (generalized or partial) as well as against a matched control group with adequately treated hypothyroidism.

RESULTS

Twenty-four boys were treated with VPA and 13 with CBZ. The weight-standard deviation score (SDS) significantly increased during the first 6 months of treatment (p < 0.001), irrespective of the drug type, but decreased between the first and the last visit (p = 0.01). In patients with generalized epilepsy, there was a slight decrease in height- and weight-SDS between the first and the last visit (p = 0.04 and p = 0.01, respectively). The height-SDS at the last visit was comparable to the parental height-SDS. The mean age at puberty onset was 11.2 and 11.4 years in the study and the control group, respectively (p = 0.08). There were no significant differences in the other parameters by treatment or epilepsy type.

CONCLUSIONS

Long-term therapy with VPA or CBZ has no significant endocrinological or metabolic adverse effect on male children and adolescents with epilepsy.

Antithyroid Antibodies Are Implicated in Epileptogenesis of Adult Patients With Epilepsy

Antithyroid antibodies (Abs) are associated with epilepsy in steroid-responsive encephalopathy, but have been rarely studied in unselected epilepsy patients. This study aimed to characterize the prevalence and associated factors of antithyroid Abs and other auto-Abs in adult patients with epilepsy.Epilepsy patients without autoimmune disorders were surveyed for antinuclear antibody (ANA), anti-β2 glycoprotein 1 antibody (aβ2GP1), anticardiolipin IgG Ab, antimicrosomal antibody (AMA), antithyroglobulin antibody (ATA), and thyroid function test.Of 319 patients, 75 (23.5%) were positive for at least 1 Ab. The most common Ab was anticardiolipin antibody (aCL) (30/319, 9.4%), followed by AMA (24/319, 7.5%), ANA (18/319, 5.6%), aβ2GP1 (18/319, 6.5%), and ATA (6/319, 3.25%). Antimicrosomal Abs were significantly more frequent in patients who were female, older at disease onset, older at the time of study, and had unknown seizure etiology. The presence of aCL was significantly associated with more frequent seizures. Most patients with antithyroid Ab were female and had focal seizures with unknown etiology.The association of different auto-Abs with different factors suggests that they may have different roles in adult patients with epilepsy. Recurrent seizures and certain antiepileptic medications may cause the production of aCL. The role of antithyroid Abs in adult focal epilepsy with unknown cause, especially in females, warrants further evaluation because of the potential implications on treatment.

Atherosclerotic effects of long-term old and new antiepileptic drugs monotherapy: a cross-sectional comparative study

This work aimed to evaluate the metabolic and atherogenic effects of long-term antiepileptic drugs in a group of Egyptian epileptic patients. Sixty-nine epileptic patients on antiepileptic drug monotherapy for at least 2 years and 34 control subjects were recruited in this study. Patients were divided into 5 subgroups according to antiepileptic drugs used (valproate, carbamazepine, lamotrigine, topiramate, and levetiracetam). Fasting lipid profile (total cholesterol, triglyceride, high-density lipoprotein cholesterol, and low-density lipoprotein cholesterol), lipoprotein(a), homocysteine, free thyroxine, thyroid-stimulating hormone, and common carotid artery intima-media thickness were measured for all subjects. Significant higher mean values of low-density lipoprotein cholesterol, low-density lipoprotein / high-density lipoprotein ratio, lipoprotein(a), homocysteine, significantly lower mean value of high-density lipoprotein cholesterol, and significantly larger diameter of common carotid artery intima-media thickness were observed in each drug-treated group versus control group. Our study supports that long-term monotherapy treatment with valproate, carbamazepine, lamotrigine, and topiramate had altered markers of vascular risk that might enhance atherosclerosis, whereas levetiracetam exerted minimal effect.

Interactions between antiepileptic drugs and hormones

Antiepileptic drugs (AEDs) are known to have endocrine side effects in both men and women. These can affect fertility, sexuality, thyroid function, and bone health, all functions of major importance for well-being and quality of life. The liver enzyme inducing antiepileptic drugs (EIAEDs), like phenobarbital, phenytoin, and carbamazepine, and also valproate (VPA), a non-EIAED, are most likely to cause such side effects. AED treatment can alter the levels of different sex hormones. EIAEDs increase sex hormone binding globulin (SHBG) concentrations in both men and women. Over time, this elevation can lead to lower levels of bioactive testosterone and estradiol, which may cause menstrual disturbances, sexual problems, and eventually reduced fertility. VPA can cause weight gain in both men and women. In women, VPA can also lead to androgenization with increased serum testosterone concentrations, menstrual disturbances, and polycystic ovaries. Lamotrigine has not been shown to result in endocrine side effects. The newer AEDs have not yet been thoroughly studied, but case reports indicate that some of these drugs could also be suspected to cause such effects if endocrine changes commence after treatment initiation. It is important to be aware of possible endocrine side effects of AEDs as they can have a major impact on quality of life, and are, at least partly, reversible after AED discontinuation.

Treatment of hypopituitarism in patients receiving antiepileptic drugs

Evidence suggests that there may be drug interactions between antiepileptic drugs and hormonal therapies, which can present a challenge to endocrinologists dealing with patients who have both hypopituitarism and neurological diseases. Data are scarce for this subgroup of patients; however, data for the interaction of antiepileptic drugs with the pituitary axis have shown that chronic use of many antiepileptic drugs, such as carbamazepine, oxcarbazepine, and topiramate, enhances hepatic cytochrome P450 3A4 (CYP3A4) activity, and can decrease serum concentrations of sex hormones. Other antiepileptic drugs increase sex hormone-binding globulin, which reduces the bioactivity of testosterone and estradiol. Additionally, the combined oestrogen-progestagen contraceptive pill might decrease lamotrigine concentrations, which could worsen seizure control. Moreover, sex hormones and their metabolites can directly act on neuronal excitability, acting as neurosteroids. Because carbamazepine and oxcarbazepine can enhance the sensitivity of renal tubules, a reduction in desmopressin dose might be necessary in patients with central diabetes insipidus. Although the effects of antiepileptic drugs in central hypothyroidism have not yet been studied, substantial evidence indicates that several antiepileptic drugs can increase thyroid hormone metabolism. However, although it is reasonable to expect a need for a thyroxine dose increase with some antiepileptic drugs, the effect of excessive thyroxine in lowering seizure threshold should also be considered. There are no reports of significant interactions between antiepileptic drugs and the efficacy of human growth hormone therapy, and few data are available for the effects of second-generation antiepileptic drugs on hypopituitarism treatment.

Evaluation of thyroid hormones in children receiving carbamazepine or valproate: a prospective study

The aim of this study was to determine the alterations in thyroid function during carbamazepine or valproate monotherapy in a prospective study. Forty patients treated with valproate, 33 patients treated with carbamazepine, and 36 control patients, all aged between 2 and 18 years, were enrolled in our study. Serum levels of thyroid hormones were measured before the beginning of the antiepileptic therapy and at 6 and 12 months of treatment. Carbamazepine-treated patients showed mean serum thyroid hormone levels significantly lower than baseline evaluation and the control group. Thyroid-stimulating hormone levels at 6 and 12 months were not significantly different in carbamazepine treated patients. Serum hormone levels did not change during valproate treatment. Thyroid-stimulating hormone levels were significantly higher at the 12th month of valproate treatment. Our data suggest that although carbamazepine causes significant alterations in thyroid hormone levels, these changes do not lead to clinical symptoms at the follow-up period of 12 months.

Adverse drug reactions induced by valproic acid

Valproic acid is a widely-used first-generation antiepileptic drug, prescribed predominantly in epilepsy and psychiatric disorders. VPA has good efficacy and pharmacoeconomic profiles, as well as a relatively favorable safety profile. However, adverse drug reactions have been reported in relation with valproic acid use, either as monotherapy or polytherapy with other antiepileptic drugs or antipsychotic drugs. This systematic review discusses valproic acid adverse drug reactions, in terms of hepatotoxicity, mitochondrial toxicity, hyperammonemic encephalopathy, hypersensitivity syndrome reactions, neurological toxicity, metabolic and endocrine adverse events, and teratogenicity.

The long-term safety of antiepileptic drugs

Antiepileptic drugs (AEDs) are used by millions of people worldwide for the treatment of epilepsy, as well as in many other neurological and psychiatric conditions. They are frequently associated with adverse effects (AEs), which have an impact on the tolerability and success of treatment. Half the people who develop intolerable AEs discontinue treatment early on after initiation, while the majority of people will continue to be exposed to their effects for long periods of time. The long-term safety of AEDs reflects their potential for chronic, cumulative dose effects; rare, but potentially serious late idiosyncratic effects; late, dose-related effects; and delayed, teratogenic or neurodevelopmental effects. These AEs can affect every body system and are usually insidious. With the exception of delayed effects, most other late or chronic AEs are reversible. To date, there is no clear evidence of a carcinogenic effect of AEDs in humans. While physicians are aware of the long-term AEs of old AEDs (the traditional liver enzyme-inducing AEDs and valproate), information about AEs of new AEDs (such as lamotrigine, levetiracetam, oxcarbazepine, topiramate or zonisamide), particularly of their teratogenic effects, has emerged over the years. Sporadic publications have raised issues about AEs of the newer AEDs eslicarbazepine, retigabine, rufinamide, lacosamide and perampanel but their long-term safety profiles may take years to be fully appreciated. Physicians should not only be aware of the late and chronic AEs of AEDs but should systematically enquire and screen for these according to the individual AED AE profile. Care should be taken for individuals with comorbid conditions that may render them more susceptible to specific AEs. Prevention and appropriate management of long-term AED AEs is expected to improve adherence to treatment, quality of life and control of epilepsy.

Impact of early life exposure to antiepileptic drugs on neurobehavioral outcomes based on laboratory animal and clinical research

Epilepsy affects approximately 1% of children under the age of 15, making it a very common neurological disorder in the pediatric population (Russ et al., 2012). In addition, ~0.4-0.8% of all pregnant women have some form of epilepsy (Hauser et al., 1996a,b; Borthen et al., 2009; Krishnamurthy, 2012). Despite the potential deleterious effects of antiepileptic drugs (AEDs) on the developing brain, their use is still required for seizure control in pregnant women (Krishnamurthy, 2012), and they represent the standard approach for treating children with epilepsy (Chu-Shore and Thiele, 2010; Quach et al., 2010; Verrotti et al., 2011). Even when AEDs are effective, there are potential side effects, including cognitive and affective changes or altered sleep and appetite. The consequences of AED exposure in development have been studied extensively (Canger et al., 1999; Modi et al., 2011a,b; Oguni, 2011). Despite intensive study, there is still debate about the long-term consequences of early life AED exposure. Here, we consider the evidence to date that AED exposure, either prenatally or in early postnatal life, has significant adverse effects on the developing brain and incorporate studies of laboratory animals as well as those of patients. We also note the areas of research where greater clarity seems critical in order to make significant advances. A greater understanding of the impact of AEDs on somatic, cognitive and behavioral development has substantial value because it has the potential to inform clinical practice and guide studies aimed at understanding the genetic and molecular bases of comorbid pathologies associated with common treatment regimens. Understanding these effects has the potential to lead to AEDs with fewer side effects. Such advances would expand treatment options, diminish the risk associated with AED exposure in susceptible populations, and improve the quality of life and health outcomes of children with epilepsy and children born to women who took AEDs during pregnancy.

Serum thyroid hormone profile and trace elements in children receiving valproic acid therapy: a longitudinal and controlled study

Valproic acid (VPA) may affect thyroid hormone profile, causing alteration in serum trace elements concentrations. The aim of this study was to prospectively investigate this relationship in children receiving VPA monotherapy for a period up to 6 months. Serum thyrotropin (TSH), free thyroxine (FT4), free triiodothyronine (FT3), thyroxine (T4), triiodothyronine (T3), thyroglobuline (TG), selenium (Se), zinc (Zn), and copper (Cu) levels were evaluated at baseline and at the 6th month in all the patients and in the control group. The mean Cu concentration in the 6th months of VPA therapy was significantly lower than that of the control group. TSH level was significantly increased in the patient group whereas FT4 was significantly decreased. The mean TSH level in the 6th month of VPA therapy was significantly higher than that of the control group, whereas mean T4 level was significantly lower. The Cu level in the 6th months of VPA therapy was positively correlated with T4 level. ΔlogCu and ΔTSH were negatively correlated. This study suggests that the alteration in the serum thyroid hormone profile during VPA therapy may result from the reduction in serum Cu levels.

Evaluation of subclinical hypothyroidism in ambulatory children with controlled epilepsy on valproate monotherapy

There are conflicting reports in the literature about the influence of valproate on thyroid function. A cross-sectional study was performed to determine the prevalence of subclinical hypothyroidism in ambulatory children aged 3 to 15 years with controlled epilepsy receiving valproate monotherapy for at least 6 months. Fifty-seven consecutive children with controlled epilepsy on valproate monotherapy and 52 healthy age- and sex-matched control children were studied. Thyroid-stimulating hormone, free thyroxine, antithyroid peroxidase antibodies, and serum valproic acid levels were measured. There was a significantly high (P = .012) prevalence of subclinical hypothyroidism (26%) in those receiving valproate monotherapy compared with healthy controls (7.7%). Median duration of valproate therapy was significantly higher (P = .039) in the subclinical hypothyroidism group (21 months, range 6-36) compared with those without subclinical hypothyroidism (14 months, range 6-25). Results of the present study suggest higher prevalence of subclinical hypothyroidism in children with controlled epilepsy on long-term valproate monotherapy.

Hypothyroidism is a rare cause of isolated constipation

The prevalence of constipation in children is high and accounts for a large percentage of pediatric and pediatric gastroenterology visits. Thyroid testing is frequently ordered to evaluate constipation and other gastrointestinal complaints in children. We reviewed all of the patients with thyroid testing ordered by our pediatric gastroenterology division during a 5-year period. We found 873 patients on whom thyroid testing was performed, and 56 patients had evidence of hypothyroidism. Nine patients had constipation and clinically significant hypothyroidism in this group; however, only 1 child had constipation as their sole presenting symptom. The contribution of occult hypothyroidism to isolated constipation in children may have been previously overestimated.

Thyroid status in a large cohort of patients with mental retardation: the TOP-R (Thyroid Origin of Psychomotor Retardation) study

OBJECTIVE

Abnormalities in thyroid state may affect development and function of the brain and result in mental retardation (MR). Thyroid parameters have not been systematically investigated in institutionalized MR subjects. The objective is to measure thyroid parameters in a novel cohort of 946 institutionalized subjects.

DESIGN

The TOP-R (Thyroid Origin of Psychomotor Retardation) study is a cross-sectional nation-wide multicentre study.

PATIENTS

Subjects with unexplained MR.

RESULTS

The majority of the MR subjects had thyroid parameters within the reference range used in our laboratory. Antiepileptic drugs (AEDs) use affected thyroid hormones (T4: 102·1 ± 1·2 vs 83·9 ± 1·2 nmol/l, P < 1 × 10(-24) ; FT4: 18·0 ± 0·2 vs 16·1 ± 0·2 pmol/l, P < 1 × 10(-9) ; T3: 1·72 ± 0·02 vs 1·57 ± 0·02 nmol/l, P < 1 × 10(-9) ; and rT3: 0·37 ± 0·01 vs 0·27 ± 0·01 nmol/l, P < 1 × 10(-28) in subjects without vs with AEDs). The prevalence of unrecognized primary hypothyroidism and hyperthyroidism was 5·2% and 2·8%, respectively.

CONCLUSIONS

We report thyroid parameters in a cohort of institutionalized subjects with MR. Our findings substantiate the fact that AEDs affect thyroid hormone levels. Future studies will be employed to investigate genetic causes of MR related to abnormalities in thyroid hormone homeostasis.

Thyroid hormone levels in children receiving carbamazepine or valproate

Antiepileptic therapy is associated with alteration of thyroid hormone levels. We evaluated the effect of valproate and carbamazepine therapy on the thyroid hormone profile of epileptic children. Subjects included children aged 2-12 years receiving therapy for at least 6 months. Free triiodothyronine, free thyroxine, and thyroid-stimulating hormone were measured by electrochemiluminescent assay in 30 children receiving carbamazepine, 34 children receiving valproate, and 30 age- and sex-matched control subjects. Groups were similar for age, body mass index, and duration of therapy. Thyroid-stimulating hormone (mean ± S.D.) was 2.67 ± 1.66, 4.53 ± 1.9, and 3.61 ± 1.75 μ IU/mL in the control, valproate, and carbamazepine group, respectively (P < 0.001). Free thyroxine was 1.39 ± 0.19, 1.40 ± 0.63, 1.11 ± 0.19 ng/dL (P = 0.009). Free triiodothyronine was 4.03 ± 0.74, 4.14 ± 0.94, 3.92 ± 0.68 pg/mL (P = 0.54). When groups were compared 2 at a time, there was no difference in free triiodothyronine (P > 0.05). Free thyroxine levels in the carbamazepine group were significantly different from valproate (P = 0.015) and control (P = 0.027). Thyroid-stimulating hormone increased with both valproate and carbamazepine compared to control but was significant with valproate (P < 0.001). We conclude that carbamazepine and valproate therapy alters thyroid functions by decreasing free thyroxine levels. Compensation by increase in thyroid-stimulating hormone is better with valproate. The need for monitoring and supplementation should be assessed further.

Hypothyroidism caused by iodine deficiency and iodine levels in enteral formulas

BACKGROUND

A 4-year-old female patient was diagnosed with hypothyroidism caused by iodine deficiency. The patient's iodine levels in serum and urine were significantly low. The iodine concentration in the enteral formula was 1.6 µg/100 kcal as measured by inductively coupled plasma mass spectrometry. The patient's iodine intake while receiving the enteral formula was calculated to be 16 µg/day, which is much lower than the recommended dietary reference intake of 80 µg for children aged 3-5 years. The purpose of this study was to assess iodine concentrations in 20 enteral nutritional formulas available in Japan in order to assess whether low iodine concentration is a characteristic of one specific formula or whether it is a more prevalent problem.

METHODS

Iodine concentrations in 20 popular nutritional formulas available in Japan, for which iodine content is not indicated in the ingredient list, were analyzed with inductively coupled plasma mass spectrometry.

RESULTS

Iodine concentrations were less than 5 µg/100 kcal and less than 10 µg/100 kcal in 13 and 18 enteral nutritional formulas, respectively.

CONCLUSIONS

Most of the enteral nutritional formulas analyzed had low iodine concentrations. These findings suggest that iodine deficiency is a likely outcome in patients who receive these formulas for a prolonged period.

Hormonal aspects of epilepsy

The relationships among hormones, epilepsy, and the medications used to treat epilepsy are complex, with tridirectional interactions that affect both men and women in various ways. Abnormalities of baseline endocrine status occur more commonly in people with epilepsy. Abnormalities are most often described for the sex steroid hormone axis, commonly presenting as sexual dysfunction in men and women with epilepsy and lower fertility. Other signs and symptoms in women with epilepsy include menstrual irregularities, premature menopause, and polycystic ovarian syndrome. The evaluation and care of adult patients with epilepsy should include considerations of the common hormonal aberrations that occur in this patient population. Questions about reproductive health disorders, sexual function, symptoms of thyroid disorders, and bone health should be part of the evaluation of all adult patients with epilepsy. Further laboratory or radiologic testing and referral to other specialists to participate in collaborative care may be warranted if underlying disorders are suspected, especially given that many of these hormone abnormalities can result in long-term health risks as well as negatively affect quality of life. AEDs and hormones have a bidirectional interaction that can impair the efficacy of contraceptive hormone treatments and of the AEDs. Endogenous hormones can influence seizure severity and frequency, resulting in catamenial patterns of epilepsy. However, this susceptibility to hormonal influences can be used to develop hormonal strategies to improve seizure control in women with epilepsy with use of cyclic PROG supplementation or alteration of the endogenous hormone release. Additionally, development of the neurosteroid analog ganaxolone provides a novel approach that can potentially be used across both genders and all age groups.

Thyroid function in the critically ill newborn and child

PURPOSE OF REVIEW

Here we review typical thyroid function alterations observed in the critically ill pediatric patient.

RECENT FINDINGS

Abnormalities in the hypothalamic-pituitary-thyroid axis have recently been confirmed to be prevalent in similar proportions in pediatric and adult patients. Significant benefits of therapy have yet to be demonstrated.

SUMMARY

At present, there is no evidence of benefit in giving thyroid hormone to patients with nonthyroidal illness who have low serum T3 or T4 concentrations, including preterm infants and postcardiac surgery patients.

Epilepsy and hormones: a critical review

Especially during growth, puberty, and menopause, profound changes including maturation of the growth hormone, sex steroid, and thyroid axes, as well as alterations in lipid homeostasis, cardiac integrity, and other enzyme systems, occur physiologically. With epilepsy, however, things are often changing, and there may be a complicated interplay between hormones, epilepsy, and antiepileptic drugs (AEDs). On the one hand, epilepsy itself possibly elicits diverse effects on different enzyme systems including sex steroids, the neuro-cardio-endocrine axis, and bone health. On the other hand, different AEDs are known to induce neuroendocrine changes (e.g., lipid metabolism) that may have deleterious consequences on health and well-being later in life. It is important for physicians and epileptologists to have in mind and to consider the endocrine effects induced by epilepsy itself or by a certain AED when starting antiepileptic therapy, especially when it is expected that long-term treatment will be necessary.