Altered amino acid homeostasis in subjects affected by fibromyalgia

Effect of menopause on circulating amino acid concentrations in women with fibromyalgia and healthy women

OBJECTIVES

Fibromyalgia is a complex syndrome that appears more frequently during menopause. No previous studies have investigated the effect of menopause on amino acids in women with fibromyalgia. Therefore, we have examined serum amino acid concentrations in premenopausal and postmenopausal women with fibromyalgia and healthy women.

STUDY DESIGN

A case-control study was carried out in 28 premenopausal and 46 postmenopausal healthy women and in 16 premenopausal and 52 postmenopausal women with fibromyalgia. This study adheres to STROBE guidelines.

MAIN OUTCOME MEASURES

Amino acid content was assayed using high-performance liquid chromatography.

RESULTS

Significant differences were found in concentrations of several amino acids (aspartic acid, glutamic acid, histidine, glycine, alanine, leucine, and taurine) between healthy premenopausal women and premenopausal women with fibromyalgia and between healthy postmenopausal women and postmenopausal women with fibromyalgia. Concentrations of other amino acids (aminoadipic acid, asparagine, threonine, arginine, 5-methyl-histidine, valine, methionine, isoleucine, phenylalanine, ornithine, branched-chain amino acids, large neutral amino acids, essential amino acids, non-essential amino acids, basic amino acids, and arginine/ornithine ratio) were found to differ between healthy postmenopausal women and postmenopausal women with fibromyalgia, but not between healthy premenopausal women and premenopausal women with fibromyalgia. No significant differences were found in serum amino acid concentrations between premenopausal and postmenopausal healthy women or between premenopausal and postmenopausal women with fibromyalgia.

CONCLUSIONS

Our results show, for the first time, that the association between menopause and fibromyalgia may increase the risk of metabolic disorders by disrupting amino acid homeostasis to a greater extent than menopause or fibromyalgia alone.

The Effectiveness of the Low-Glycemic and Insulinemic (LOGI) Regimen in Maintaining the Benefits of the VLCKD in Fibromyalgia Patients

Background: Fibromyalgia (FM) is a chronic disorder that causes damage to the neuro-muscular system and alterations in the intestinal microbiota and affects the psychological state of the patient. In our previous study, we showed that 22 women patients subjected to a specific very low-carbohydrate ketogenic therapy (VLCKD) showed an improvement in clinical scores as well as neurotransmission-related and psychological dysfunctions and intestinal dysbiosis. Furthermore, NMR metabolomic data showed that changes induced by VLCKD treatment were evident in all metabolic pathways related to fibromyalgia biomarkers. Methods: Based on this evidence, we extend our investigation into dietary interventions for fibromyalgia by evaluating the impact of transitioning from a VLCKD to a low-glycemic insulinemic (LOGI) diet over an additional 45-day period. Therefore, participants initially following a VLCKD were transitioned to the LOGI diet after 45 days to determine whether the improvements in FM symptoms and metabolic dysfunctions achieved through VLCKD could be sustained with LOGI. Results: Our findings suggested that while VLCKD serves as an effective initial intervention for correcting metabolic imbalances and alleviating FM symptoms, transitioning to a LOGI diet offers a practical and sustainable dietary strategy. This transition preserves clinical improvements and supports long-term adherence and quality of life, underscoring the importance of adaptable nutritional therapies in chronic disease management. Control patients who adhered only to the LOGI diet for 90 days showed only modest improvement in clinical and psychological conditions, but not elimination of fibromyalgia symptoms. Conclusions: In conclusion the LOGI diet is an excellent alternative to maintain the results obtained from the regime VLCKD.

Early Diagnosis of Fibromyalgia Using Surface-Enhanced Raman Spectroscopy Combined with Chemometrics

Fibromyalgia (FM) is a chronic muscle pain disorder that shares several clinical features with other related rheumatologic disorders. This study investigates the feasibility of using surface-enhanced Raman spectroscopy (SERS) with gold nanoparticles (AuNPs) as a fingerprinting approach to diagnose FM and other rheumatic diseases such as rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), osteoarthritis (OA), and chronic low back pain (CLBP). Blood samples were obtained on protein saver cards from FM (n = 83), non-FM (n = 54), and healthy (NC, n = 9) subjects. A semi-permeable membrane filtration method was used to obtain low-molecular-weight fraction (LMF) serum of the blood samples. SERS measurement conditions were standardized to enhance the LMF signal. An OPLS-DA algorithm created using the spectral region 750 to 1720 cm-1 enabled the classification of the spectra into their corresponding FM and non-FM classes (Rcv > 0.99) with 100% accuracy, sensitivity, and specificity. The OPLS-DA regression plot indicated that spectral regions associated with amino acids were responsible for discrimination patterns and can be potentially used as spectral biomarkers to differentiate FM and other rheumatic diseases. This exploratory work suggests that the AuNP SERS method in combination with OPLS-DA analysis has great potential for the label-free diagnosis of FM.

Nutrition and Chronobiology as Key Components of Multidisciplinary Therapeutic Interventions for Fibromyalgia and Associated Chronic Fatigue Syndrome: A Narrative and Critical Review

Fibromyalgia (FM) is often accompanied by chronic fatigue syndrome (CFS). It is a poorly understood disorder that mainly affects women and leads to chronic pain, fatigue, and insomnia, among other symptoms, which decrease quality of life. Due to the inefficiency of current pharmacological treatments, increasing interest is being directed towards non-pharmacological multicomponent therapies. However, nutrition and chronobiology are often overlooked when developing multicomponent therapies. This narrative and critical review explore the relevance of nutritional and chronobiological strategies in the therapeutic management of FM and the often-associated CFS. Reviewed literature offers scientific evidence for the association of dietary habits, nutrient levels, body composition, gut microbiota imbalance, chronobiological alterations, and their interrelation with the development and severity of symptoms. This review highlights the key role of nutrition and chronobiology as relevant and indispensable components in a multidisciplinary approach to FM and CFS.

Predictive Ability of Serum Amino Acid Levels to Differentiate Fibromyalgia Patients from Healthy Subjects

BACKGROUND

Fibromyalgia is a complex illness to diagnose and treat.

OBJECTIVES

To evaluate a broad range of circulating free amino acid (AA) levels in fibromyalgia patients as well as the ability of the AAs to differentiate fibromyalgia patients from healthy subjects.

DESIGN

We carried out a case-control study to evaluate AA levels in 62 patients with fibromyalgia and 78 healthy subjects. This study adheres to the STROBE guidelines.

METHODS

AAs content was assayed by HPLC in serum samples. The predictive value of AA levels in fibromyalgia was determined by receiver operating characteristic (ROC) curve and forward binary logistic regression analyses.

RESULTS

Fibromyalgia patients showed higher serum levels of aspartic acid, glutamic acid, aminoadipic acid, asparagine, histidine, 3-methyl-histidine, 5-methyl-histidine, glycine, threonine, taurine, tyrosine, valine, methionine, isoleucine, phenylalanine, leucine, ornithine, lysine, branched chain AAs (BCAAs), large neutral AAs, essential AAs (EAAs), non-essential AAs (NEAAs), basic AAs, EAAs/NEAAs ratio, phenylalanine/tyrosine ratio, and global arginine bioavailability ratio than the controls. Serum alanine levels were lower in patients than in controls. According to ROC analysis, most of these AAs may be good markers for differentiating individuals with fibromyalgia from healthy subjects. Results of logistic regression showed that the combination of glutamic acid, histidine, and alanine had the greatest predictive ability to diagnose fibromyalgia.

CONCLUSIONS

Our results show an imbalance in serum levels of most AAs in patients with fibromyalgia, which suggest a metabolic disturbance. The determination of serum levels of these AAs may aid in the diagnosis of fibromyalgia, in combination with clinical data of the patient.

Metabolomics analysis of plasma samples of patients with fibromyalgia and electromagnetic sensitivity using GC-MS technique

Fibromyalgia (FM) is a chronic and systemic condition that causes widespread chronic pain, asthenia, and muscle stiffness, as well as in some cases depression, anxiety, and disorders of the autonomic system. The exact causes that lead to the development of FM are still unknown today. In a percentage of individuals, the symptoms of FM are often triggered and/or exacerbated by proximity to electrical and electromagnetic devices. Plasma metabolomic profile of 54 patients with fibromyalgia and self-reported electromagnetic sensitivity (IEI-EMF) were compared to 23 healthy subjects using gas chromatography-mass spectrometry (GC-MS) coupled with multivariate statistical analysis techniques. Before the GC-MS analysis the plasma samples were extracted with a modified Folch method and then derivatized with methoxamine hydrochloride in pyridine solution and N-trimethylsilyltrifuoroacetamide. The combined analysis allowed to identify a metabolomic profile able of distinguishing IEI-EMF patients and healthy subjects. IEI-EMF patients were therefore characterized by the alteration of 19 metabolites involved in different metabolic pathways such as energy metabolism, muscle, and pathways related to oxidative stress defense and chronic pain. The results obtained in this study complete the metabolomic "picture" previously investigated on the same cohort of IEI-EMF patients with ¹H-NMR spectroscopy, placing a further piece for better understanding the pathophysiological mechanisms in patients with IEI-EMF.

Fibromyalgia: Pathogenesis, Mechanisms, Diagnosis and Treatment Options Update

Fibromyalgia is a syndrome characterized by chronic and widespread musculoskeletal pain, often accompanied by other symptoms, such as fatigue, intestinal disorders and alterations in sleep and mood. It is estimated that two to eight percent of the world population is affected by fibromyalgia. From a medical point of view, this pathology still presents inexplicable aspects. It is known that fibromyalgia is caused by a central sensitization phenomenon characterized by the dysfunction of neuro-circuits, which involves the perception, transmission and processing of afferent nociceptive stimuli, with the prevalent manifestation of pain at the level of the locomotor system. In recent years, the pathogenesis of fibromyalgia has also been linked to other factors, such as inflammatory, immune, endocrine, genetic and psychosocial factors. A rheumatologist typically makes a diagnosis of fibromyalgia when the patient describes a history of pain spreading in all quadrants of the body for at least three months and when pain is caused by digital pressure in at least 11 out of 18 allogenic points, called tender points. Fibromyalgia does not involve organic damage, and several diagnostic approaches have been developed in recent years, including the analysis of genetic, epigenetic and serological biomarkers. Symptoms often begin after physical or emotional trauma, but in many cases, there appears to be no obvious trigger. Women are more prone to developing the disease than men. Unfortunately, the conventional medical therapies that target this pathology produce limited benefits. They remain largely pharmacological in nature and tend to treat the symptomatic aspects of various disorders reported by the patient. The statistics, however, highlight the fact that 90% of people with fibromyalgia also turn to complementary medicine to manage their symptoms.

Metabolomics and psychological features in fibromyalgia and electromagnetic sensitivity

Fibromyalgia (FM) as Fibromyalgia and Electromagnetic Sensitivity (IEI-EMF) are a chronic and systemic syndrome. The main symptom is represented by strong and widespread pain in the musculoskeletal system. The exact causes that lead to the development of FM and IEI-EMF are still unknown. Interestingly, the proximity to electrical and electromagnetic devices seems to trigger and/or amplify the symptoms. We investigated the blood plasma metabolome in IEI-EMF and healthy subjects using ¹H NMR spectroscopy coupled with multivariate statistical analysis. All the individuals were subjected to tests for the evaluation of psychological and physical features. No significant differences between IEI-EMF and controls relative to personality aspects, Locus of Control, and anxiety were found. Multivariate statistical analysis on the metabolites identified by NMR analysis allowed the identification of a distinct metabolic profile between IEI-EMF and healthy subjects. IEI-EMF were characterized by higher levels of glycine and pyroglutamate, and lower levels of 2-hydroxyisocaproate, choline, glutamine, and isoleucine compared to healthy subjects. These metabolites are involved in several metabolic pathways mainly related to oxidative stress defense, pain mechanisms, and muscle metabolism. The results here obtained highlight possible physiopathological mechanisms in IEI-EMF patients to be better defined.

Nutritional Interventions in the Management of Fibromyalgia Syndrome

Fibromyalgia (FM) is a multifactorial syndrome of unknown etiology, characterized by widespread chronic pain and various somatic and psychological manifestations. The management of FM requires a multidisciplinary approach combining both pharmacological and nonpharmacological strategies. Among nonpharmacological strategies, growing evidence suggests a potential beneficial role for nutrition. This review summarizes the possible relationship between FM and nutrition, exploring the available evidence on the effect of dietary supplements and dietary interventions in these patients. Analysis of the literature has shown that the role of dietary supplements remains controversial, although clinical trials with vitamin D, magnesium, iron and probiotics' supplementation show promising results. With regard to dietary interventions, the administration of olive oil, the replacement diet with ancient grains, low-calorie diets, the low FODMAPs diet, the gluten-free diet, the monosodium glutamate and aspartame-free diet, vegetarian diets as well as the Mediterranean diet all appear to be effective in reducing the FM symptoms. These results may suggest that weight loss, together with the psychosomatic component of the disease, should be taken into account. Therefore, although dietary aspects appear to be a promising complementary approach to the treatment of FM, further research is needed to provide the most effective strategies for the management of FM.

Comparison between Acupuncture and Nutraceutical Treatment with Migratens® in Patients with Fibromyalgia Syndrome: A Prospective Randomized Clinical Trial

OBJECTIVES

Fibromyalgia syndrome (FMS) is a chronic clinical condition characterized by pain, fatigue, altered sleep, and cognitive disturbances. The purpose of this study was to compare two alternative treatments (nutraceutical and acupuncture) in FMS patients through a randomized clinical trial.

RESEARCH METHODS

A total of 60 FMS female patients were randomized for treatment with a nutritional combination containing coenzyme Q10, vitamin D, alpha-lipoic acid, magnesium, and tryptophan (Migratens® Group) or acupuncture treatment (Acupuncture Group) performed according the principles of traditional Chinese medicine (TCM), both for 3 months. Changes in pain and in quality of life (QoL) measured with a Fibromyalgia Impact Questionnaire Score-Revised (FIQ-R) and the Fibromyalgia Severity Scale (FSS) were performed at 1, 3, and 6 months after the start of treatments.

RESULTS

A total of 55 patient completed the study (21 in the Migratens® Group and 34 in the Acupuncture Group). Migratens® treatment shows a statistically significant reduction of pain 1 month after the start of therapy (T1, p = 0.025), strengthened after 3 months with maintenance of treatment (p = 0.012). The efficacy in reducing pain was apparent in the Acupuncture Group at all post-treatment determinations and at follow-up (T1 and T2 p = <0.001). Regarding QoL, improvement in FIQ-R and FSS values was revealed in both groups.

CONCLUSION

The nutraceutical approach with Migratens® seems to be an effective option to for patients with FMS. Our experience confirmed also the validity of acupuncture in these patients. Considering the complexity of the management of FMS patients, our results suggest a cyclical and sequential, or even concurrent treatment with different approaches, to improve the efficacy and the compliance of patients to long-term treatment.

Tryptophan in health and disease

Tryptophan (TRP), an essential amino acid in mammals, is involved in several physiological processes including neuronal function, immunity, and gut homeostasis. In humans, TRP is metabolized via the kynurenine and serotonin pathways, leading to the generation of biologically active compounds, such as serotonin, melatonin and niacin. In addition to endogenous TRP metabolism, resident gut microbiota also contributes to the production of specific TRP metabolites and indirectly influences host physiology. The variety of physiologic functions regulated by TRP reflects the complex pattern of diseases associated with altered homeostasis. Indeed, an imbalance in the synthesis of TRP metabolites has been associated with pathophysiologic mechanisms occurring in neurologic and psychiatric disorders, in chronic immune activation and in the immune escape of cancer. In this chapter, the role of TRP metabolism in health and disease is presented. Disorders involving the central nervous system, malignancy, inflammatory bowel and cardiovascular disease are discussed.

Metabolomic Differentials in Women With and Without Fibromyalgia

A nontargeted plasma metabolomic analysis was conducted to compare differentially expressed metabolites in women with and without fibromyalgia (FM) using data and samples collected from two parent studies in women with FM (n = 20) and comparative data collected from newly recruited age‐matched women (n = 20). Blood plasma samples were analyzed for metabolite content using liquid chromatography mass spectrometry. Consolidation of positive and negative ion mode metabolomics data with fold change (>2 or <0.5) and variable importance of projection scores ≥1 revealed statistically significant metabolites comparing samples from women with and without FM. Metabolite profiles in patients with FM differed from the comparison group in energy, lipid and amino acid metabolites reflecting heightened oxidative stress, inflammation, and tryptophan degradation in patients with FM. Study results may contribute to further identification of unique metabolomic profiles enhancing understanding of the pathophysiology of FM and for the development of effective therapeutic options.

The gadolinium hypothesis for fibromyalgia and unexplained widespread chronic pain

Fibromyalgia (FM) is a chronic, painful, heterogeneous, and common disorder carrying a substantial socio-economical burden. It lacks effective cures and its aetiology is still unknown. There exists evidence for central and peripheral neurological contribution to the symptoms but grasping the real source of abnormal nervous system sensitization remains an ongoing challenge. There exists an association between an injury/trauma and the onset of the symptoms, but a causal relationship has not been yet sufficiently supported by scientific evidence. I postulate a role for gadolinium-based contrast agents and retention of gadolinium in the body. This conjecture breaks the hypothesis of a direct role for a physical injury/trauma per se in favour of an indirect one by the subsequent diagnostic procedures. It creates a new link between retention of gadolinium in the body and painful conditions as FM and unexplained chronic widespread pain reported after a trauma, surgery, or medical illness. Experimental evidence demonstrates possible retention of gadolinium species in human body, still lacking conclusive answers on their pathological consequences. Notwithstanding, there exist some initial data that report unexplained chronic widespread pain and symptoms of FM in those patients: they are suggestive for pathological consequences associated with gadolinium retention. Besides clear compelling symptoms overlapping, biochemical findings are provided to sustain the hypothesis of a role for gadolinium in the disease process focusing on neurotransmitters, endogenous metal cations, cytokines, and muscle tissue. Experimental findings strongly support the hypothesis of impairment at the cellular, intracellular, and systemic levels in FM. And these data are highly compatible with collateral effects associated with the interference of the gadolinium ion and its pharmaceutical chelates into biochemical pathways in vivo. The hypothesis presented in this article, along with the support of scientific evidence, links FM and unexplained chronic widespread pain reported after a trauma, surgery, or medical illness to retention of gadolinium in the body. If the hypothesis is confirmed, it could improve diagnosis and prevention, while providing a ground for development of new treatments.

Fibromyalgia Syndrome: A Case Report on Controlled Remission of Symptoms by a Dietary Strategy

A 34-year-old woman suffered from significant chronic pain, depression, non-restorative sleep, chronic fatigue, severe morning stiffness, leg cramps, irritable bowel syndrome, hypersensitivity to cold, concentration difficulties, and forgetfulness. Blood tests were negative for rheumatic disorders. The patient was diagnosed with Fibromyalgia syndrome (FMS). Due to the lack of effectiveness of pharmacological therapies in FMS, she approached a novel metabolic proposal for the symptomatic remission. Its core idea is supporting serotonin synthesis by allowing a proper absorption of tryptophan assumed with food, while avoiding, or at least minimizing the presence of interfering non-absorbed molecules, such as fructose and sorbitol. Such a strategy resulted in a rapid improvement of symptoms after only few days on diet, up to the remission of most symptoms in 2 months. Depression, widespread chronic pain, chronic fatigue, non-restorative sleep, morning stiffness, and the majority of the comorbidities remitted. Energy and vitality were recovered by the patient as prior to the onset of the disease, reverting the occupational and social disabilities. The patient episodically challenged herself breaking the dietary protocol leading to its negative test and to the evaluation of its benefit. These breaks correlated with the recurrence of the symptoms, supporting the correctness of the biochemical hypothesis underlying the diet design toward remission of symptoms, but not as a final cure. We propose this as a low risk and accessible therapeutic protocol for the symptomatic remission in FMS with virtually no costs other than those related to vitamin and mineral salt supplements in case of deficiencies. A pilot study is required to further ground this metabolic approach, and to finally evaluate its inclusion in the guidelines for clinical management of FMS.

Fibromyalgia Syndrome: A Metabolic Approach Grounded in Biochemistry for the Remission of Symptoms

Fibromyalgia syndrome (FMS) is a chronic, complex, and heterogeneous disorder of still poorly understood etiopathophysiology associated with important musculoskeletal widespread pain, fatigue, non-restorative sleep, and mood disturbances. It is estimated to afflict 2–3% of the worldwide population, with clean prevalence among women. The objective of this paper is to propose a novel treatment for symptomatic remission of FMS, grounded in biochemistry and consisting in the withdrawal from the diet of molecules that can indirectly trigger the symptoms. The hypothesis develops from the evidence that low serotonin levels are involved in FMS. Serotonin is synthesized starting from the essential amino acid tryptophan. The presence of non-absorbed molecules in the gut, primarily fructose, reduces tryptophan absorption. Low tryptophan absorption leads to low serotonin synthesis that triggers FMS symptoms. Moreover not-absorbed sugars could also produce a microbiota deterioration activating a positive feedback loop: the increasing microbiota deterioration reduces the functionality of absorption both of fructose and tryptophan in the gut, entering a vicious circle. The therapeutic idea is to sustain serotonin synthesis allowing the proper tryptophan absorption. The core of the cure treatment is the exclusion from the diet of some carbohydrates and the marked reduction of some others. The main target is the limitation of total dietary fructose as marked as possible. It could be an effective strategy to get the remission of symptoms acting on the impaired biochemical pathways. The straying from the treatment is expected to cause the reappear of the symptoms.

Free amino acids in fibromyalgia syndrome: relationship with clinical picture

The objectives of our study were to evaluate free amino acid (FAA) concentrations in the serum of patients affected by fibromyalgia syndrome (FMS) and to determine the relationships between FAA levels and FMS clinical parameters. Thus, serum amino acid concentrations were quantified (HPLC analysis) in 23 females with fibromyalgia (according to the American College of Rheumatology classification criteria) and 20 healthy females. The results showed significantly higher serum concentrations of aspartate, cysteine, glutamate, glycine, isoleucine, leucine, methionine, ornithine, phenylalanine, sarcosine, serine, taurine, tyrosine and valine in FMS patients vs. healthy controls. Patients with higher Fibromyalgia Impact Questionnaire (FIQ) scores showed increased levels of alanine, glutamine, isoleucine, leucine, phenylalanine, proline and valine. In conclusion, our results indicate an imbalance in some FAAs in FMS patients. Increased Glu is particularly interesting, as it could explain the deficit in monoaminergic transmission involved in pain.

Plasma amino acids changes in complex regional pain syndrome

Complex regional pain syndrome (CRPS) is a severe chronic pain condition that most often develops following trauma. Blood samples were collected from 220 individuals, 160 CRPS subjects, and 60 healthy pain-free controls. Plasma amino acid levels were compared and contrasted between groups. L-Aspartate, L-glutamate, and L-ornithine were significantly increased, whereas L-tryptophan and L-arginine were significantly decreased in CRPS subjects as compared to controls. In addition, the L-kynurenine to L-tryptophan ratio demonstrated a significant increase, whereas the global arginine bioavailability ratio (GABR) was significantly decreased in the CRPS subjects. The CRPS subjects demonstrated a significant correlation between overall pain and the plasma levels of L-glutamate and the L-kynurenine to L-tryptophan ratio. CRPS subjects also showed a correlation between the decrease in plasma L-tryptophan and disease duration. This study shows that CRPS subjects exhibit significant changes in plasma levels of amino acids involved in glutamate receptor activation and in amino acids associated with immune function as compared to healthy pain-free controls. A better understanding of the role plasma amino acids play in the pathophysiology of CRPS may lead to novel treatments for this crippling condition.

A Brief Historic Overview of Clinical Disorders Associated with Tryptophan: The Relevance to Chronic Fatigue Syndrome (CFS) and Fibromyalgia (FM)

Last century there was a short burst of interest in the tryptophan related disorders of pellagra and related abnormalities that are usually presented in infancy.1,2 Nutritional physiologists recognized that a severe human dietary deficiency of either tryptophan or the B group vitamins could result in central nervous system (CNS) sequelae such as ataxia, cognitive dysfunction and dysphoria, accompanied by skin hyperpigmentation.3,4 The current paper will focus on the emerging role of tryptophan in chronic fatigue syndrome (CFS) and fibromyalgia (FM).

RP-LC of phenylthiocarbamyl amino acid adducts in plasma acetonitrile extracts: use of multiple internal standards and variable wavelength UV detection

The measurement of physiological amino acids in body fluids and circulating cells can be relevant in the search for biological correlates of neuropsychiatric, neurological, body weight, and pain diseases. Several techniques are available for the quantitative analysis of free amino acids, including UV detection after precolumn derivatization. These systems have low specificity due to possible interferences at the analytical wavelength. Another problem linked to these methods is variations potentially occurring during extraction, derivatization, and chromatography of amino acids in biological matrices. We present here a modified reversed-phase LC of phenylthiocarbamyl amino acids in plasma deproteinated by the organic solvent acetonitrile. Specificity was monitored by UV-photodiode array detection and accuracy was controlled by a plasma spiking procedure with three internal standards. A dual-wavelength spectrophotometry (254, 283 nm) was used to quantify coeluting ornithine and tryptophan adducts. The method is simple and economical and enables the measure of most plasma amino acids for clinical research, also during therapeutic drug monitoring. Dual UV-fluorimetric detection solutions can improve its sensitivity.

Thyroid autoimmunity may represent a predisposition for the development of fibromyalgia?

In our previous study, we observed that the presence of autoimmune thyroid disease worsens fibromyalgia (FM) symptoms. The aims of this study are to evaluate whether there is a predisposition for the development of FM in patients with Hashimoto's thyroiditis (HT) with or without subclinical hypothyroidism (SCH) and in patients with SCH alone and what is the weight of antithyroid antibody positivity and SCH on FM comorbidity. Fifty-two patients, 39 affected by HT with or without SCH and 13 by SCH, were matched with 37 patients affected by FM and 25 healthy subjects. Blood samples were collected from all study subjects for the determination of serum TSH, free triiodothyronine, free thyroxine, antithyroperoxidase antibody (TPOAb), antithyroglobulin antibody (TgAb) and non-organ-specific autoantibodies. Clinical assessment of patients and controls included the "Fibromyalgia Impact Questionnaire" (FIQ), while pain severity was evaluated using a visual analogue scale (VAS). Patients and controls were also characterized by the presence of diffuse pain, fatigue, paresthesiae, muscle spasms, non-restful sleep, tension headache and presence of mood disorders. FM comorbidity resulted in twelve HT subjects (31%) and none in SCH patient. In particular, FM comorbidity in HT patients without SCH was 33.3% and in HT patients with SCH was 28.5%. Based on our data, we speculate that maybe there is more than a hypothesis regarding the cause-effect relation between thyroid autoimmunity and the presence of FM, thus suggesting a hypothetical role of thyroid autoimmunity in FM pathogenesis.