Ocular myasthenia gravis, Hashimoto's thyroiditis, iron deficiency anemia, and reactive hypoglycemia/Okuler myastenia gravis, Hashimoto tiroiditi, demir eksikligi anemisi ve reaktif hipoglisemi.
Autoimmune diseases (AD) are conditions in which there is a development of antibodies against self cells and/or organs. AD could either be organ-specific or non-organ specific (systemic) in clinical presentation (1). Myasthenia gravis (MG) is an autoimmune disease characterized by impaired neuromuscular transmission due to circulating antiacetylcholine receptor autoantibodies (AchRAb) (2). The clinical expression of MG varies ranging from a mild localized disease, such as ocular, to a severe generalized disease. In epidemiological studies autoimmune thyroid disease (AITD) has been observed in approximately 5-10% of MG patients, and a higher frequency of thyroid antibodies has been observed in ocular myastenia gravis (OMG) compared to generalized myastenia gravis (GMG), whereas a fairly low incidence of MG (0.2%) has been reported in patients with AITD (2,3,4). In our study, we present a patient with ocular myasthenia, Hashimoto's thyroiditis, and iron deficiency anemia who later developed reactive hypoglycemia.
A 25- year-old woman with complaints of fluctuating extraocular muscle weakness, ptosis, and diplopia since 3 years was examined. Physical and the remaining neurological examination were normal. Myasthenia gravis (MG), type I (ocular MG according to Osserman criteria), was confirmed by an elevated titer of anti-acetylcholine receptor antibodies in serum (7 nmol/I, normal <0.6 nmol/I) and a clear improvement in eye muscle weakness a few seconds after the administration of edrophonium. Nerve conduction studies, needle electromyography, repetitive stimulation tests, and mediastinal magnetic resonance imaging were normal. The coexistence of Hashimoto's thyroiditis was diagnosed by the presence of a diffuse thyroid enlargement on thyroid ultrasonography, elevated titers of anti-thyroglobulin antibodies, thyroid peroxidase antibodies, thyroid stimulating hormone, and a decreased titer of free-T4 in blood samples (Table 1) and lymphocytic infiltration on fine needle aspiration biopsy. Hyperlipidemia and iron deficiency anemia were also noted (Table 1). The other biochemical parameters were within normal ranges. The patient was also examined for unusual combination of autoimmune conditions. The computed tomography of the abdomen and pelvis, and transduodenal endoscopic ultrasound were negative for insulinoma. The levels of C-reactive protein, anti-streptolysin O, rheumatoid factor, anti-SLE in blood samples were normal. Diplopia and ptosis have regressed with 180 mg/day pyridostigmine bromide. Hypothyroidism has been treated with L-Thyroxine sodium 0.25 mg/day. Routine hematological and biochemical blood tests were repeated every 2 months. Iron deficiency anemia has been treated with ferroglycerine sulfate 450mg/day for 2 months and 225 mg/day for 4 months, and thyroid function tests were not affected during this treatment.
Eight months later, as autonomic findings like sweating, palpitation and hunger have developed postprandially, oral glucose tolerance test (OGTT) using 75 g of glucose has been applied and her blood sugar was periodically measured every hour. The plasma glucose reached a nadir of 0.48 g/I at the end of the 3rd hour and hypoglycemic symptoms have been examined (Table 2). Fasting insulin level was 6.91 j IU/mL, while the postprandial insulin level has reached a nadir of 87 j IU/mL and reactive hypoglycemia has been diagnosed. The OGTT test has been repeated a month later and the similar results have been detected. The computed tomography of the abdomen and pelvis were normal, and transduodenal endoscopic ultrasound was negative for insulinoma. She was treated by avoidance of sweets and high-sugar foods, and eating meals at regular times. On her follow-up period, at the end of the 24th months, diplopia and ptosis did not recur under the treatment of pyridostigmine bromide and she did not develop generalized muscle involvement. Routine hematological and biochemical tests were also in normal ranges.
Genetic, immune, hormonal, and environmental factors are associated with the multifactorial origin of autoimmunity. When one or more of these factors are altered, a "switch" from one autoimmune condition to another can occur (2). Chronic autoimmune thyroidism (Hashimoto's), as well as immunogenic hyperthyroidism (Graves-Basedow) are frequently associated with autoimmune diseases of other organs, such as: chronic insufficiency of salivary glands (Sjogren's), autoimmune hemolytic anemia, megalocytic pernicious anemia, thrombocytopenia, rheumatoid arthritis, diabetes mellitus (more often type 2, but also type 1), and other autoimmune diseases such as systemic diseases of connecting tissue (Systemic Lupus erythematosus-SLE, Sclerodermia) (1,4).
Autoimmune thyroid disease (AITD) is a multifactorial, genetic disease that is the sequelae of impaired immunoregulation, tolerance and poor recognition of one's own proteins, oligopolysaccharides and polypeptides, due to development of somatic lymphocyte mutations (4). AITD is manifested by different clinical and morphological entities, inter-related by etiopathogenetic association, i.e., all of them are caused by disorder of immune system regulation. Hashimoto's thyroiditis (HT) and MG are infrequently associated, while Graves' disease is a quite frequent phenomenon in MG (5). Though it was suggested that AITD occurs in approximately 5-10% of MG patients, in another study, 46 patients with MG were investigated and it was observed that two (4%) had Graves' disease, five (12%) were euthyroid with autonomously functioning thyroid tissue, the remaining 39 patients had no thyroid disease. One year earlier, the same authors reported a somewhat higher incidence of thyroid disease in a larger series (n=104) of MG patients (6% with thyrotoxicosis, 2% with hypothyroidism, 12% had antithyroglobulin antibodies and 28% had antimicrosomal antibodies) (6). Marino et al found a prevalence of AITD in their MG series as 28.5% (26/91): 4.4% (4/91) with hyperthyroid Graves' disease (GD), 3.3% (3/91) with euthyroid GD, 10.9% (10/91) with euthyroid Hashimoto's thyroiditis (HT), and 9.9% (9/91) with hypothyroid HT or idiopathic myxedema (2).
In some studies, an increased association of autoimmune disorders was found in OMG than GMG, while a higher frequency in GMG compared to OMG was found by others (2). Several hypotheses have been considered for the increased association between OMG and thyroid autoimmunity. First, OMG and GMG might actually represent separate diseases with different spectra of associated diseases, and different pathogenetic mechanisms are responsible for them. Second, as several experimental data suggest that thyroid antigens are present in ocular tissues, an immunological cross-reactivity against epitopes or autoantigens shared by the thyroid and the eye muscles might be the basis of this association. Third, they might share a common peculiar genetic background (7,8,9). Weissel et al have investigated 74 consecutive patients with MG, and found only 1 euthyroid patient on L-thyroxine therapy with HT and another patient with mildly elevated TSH without elevated thyroid antibodies, and they have suggested that autoimmune thyroid disease may be associated with MG, but the occurrence of thyroid dysfunction induced by autoimmunity is a very rare phenomenon in MG (10).
The coexistence of Hashimoto's thyroiditis and myastenia gravis can be diagnosed by the presence of a diffuse thyroid enlargement, anti-thyroglobulin and anti-microsomal antibodies and a lowered thyroidal 131-I uptake (2). Since HT as well as MG has an abnormality of T lymphocyte regulatory function, and the autoimmune process in both diseases is directed against cell membrane receptors, they can be considered as pathogenetically related (8). Unrecognized HT progressively leads to hypothyroidism with hyperlipidemia, blood vessel changes, osteoporosis, deformities, invalidity which substantially reduces the quality of life of the patient and requires medical attention (10).
In the literature there are few cases with MG and HT who also developed an unusual combination of autoimmune conditions. One of these patients with Type 1 diabetes mellitus has developed generalized MG, Addisonian pernicious anaemia, adrenalitis and thyroiditis which did not fit into the Type 1 or Type 2 classical polyendocrine deficiency syndromes (11). Another patient with generalized MG was complicated by sarcoidosis and HT, while one patient was complicated by type 1 DM, autoimmune hepatitis and HT, suggesting that the common underlying immunological abnormalities for these disorders, such as a certain defective cellular immunity, are responsible for the pathomechanism to induce the patient condition (5,12,13).
Several minerals and trace elements, such as iodine and iron, are essential for normal thyroid hormone metabolism. Though patients with AITD have a higher prevalence of vitamin B12 deficiency and pernicious anemia, studies in animals and adults have indicated iron deficiency anemia to be associated with altered thyroid hormone metabolism. Iron deficiency impairs thyroid hormone synthesis by reducing activity of heme-dependent thyroid peroxidase (14). Chen et al have reported the occurrence of megaloblastic anemia in a young woman with chronic autoimmune thyroiditis, who has presented with iron deficiency anemia that has been diagnosed initially (15). Our patient has been diagnosed as ocular myastenia, and during the investigations a coexistence with Hashimoto's thyroiditis was observed. She also had an iron deficiency anemia, and during her follow-up period reactive hypoglycemia has developed. The coexistence of myastenia gravis, Hashimoto's thyroiditis and reactive hypoglycemia was not found in the literature.
In conclusion, we should take into consideration the association and the importance of the recognition of the above-mentioned pathologies with myastenia gravis, and by early diagnosis and multidisciplinary treatment, to take secondary preventive measures, and in that way, to avoid the development of comorbidity and complications. This suggests that the autoantibody, biochemical and haematological screening of affected individuals should be extended to anticipate a wider range of potential autoimmune conditions.
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Fusun Mayda Domac, Handan Misirli, Ece Boylu *, Beratgul Ozer
Haydarpasa Numune Training and Research Hospital, Department of 1st Neurology, Istanbul, Turkey
* GATA Haydarpasa Training Hospital, Department of Neurology, Istanbul, Turkey
Address for Correspondence: Fusun Mayda Domac, MD, Haydarpapa Numune Training and Research Hospital, Department of 1st Neurology, lkkodar, Turkey Phone: +90 216 455 67 58 Gsm: +90 532 282 59 50 E-mail: email@example.com Recevied: 08.04.2009 Accepted: 06.08.2009
Turkish Journal of Endocrinology and Metabolism, published by Galenos Publishing. All rights reserved.
Table 1. Pathological blood parameters Serum levels of the patient Anti-acetylcholine receptor antibody 7 nmol/L [up arrow] Anti-thyroglobulin antibody 211.8 IU/mL [up arrow] Thyroid peroxidase antibody 356.4 IU/mL [up arrow] Thyroid stimulating hormone 8.21 uIU/mL [up arrow] Free-T4 1.03 ng/dL [down arrow] Hemoglobin 10.4 g/dL [down arrow] Iron 18 ng/dL [down arrow] Total iron binding capacity 417 [micro]g/dL [up arrow] Ferritin 7.28 ng/dL [down arrow] Total cholesterol 266 mg/dL [up arrow] Trygliseride 191 mg/dL [down arrow] LDL cholesterol 174mg/dL [up arrow] VLDL cholesterol 38mg/dL [up arrow] HbA1c 5.53 Insulin (postprandial) 87 [micro]U/mL [up arrow] Normal levels Anti-acetylcholine receptor antibody <0.6 nmol/L Anti-thyroglobulin antibody 0-115 IU/mL Thyroid peroxidase antibody 0-34 IU/mL Thyroid stimulating hormone 0.27-4.2 IU/mL Free-T4 1.8-4.6 ng/dL Hemoglobin 11.7-15.5g/dL Iron 25-145 ng/dL Total iron binding capacity 187-395 [micro]g/dL Ferritin 13-150 ng/dL Total cholesterol 110-200 mg/dL Trygliseride <150 mg/dL LDL cholesterol <160mg/dL VLDL cholesterol <30mg/dL HbA1c %<6.0 Insulin (postprandial) 2.6-24.9 [micro]U/mL Table 2. Results of oral glucose tolerance test OGTT g/I Glucose (fasting) 0.86 30 minute 1.37 60 minute 1.21 120 minute 1.09 180 minute 0.46 [down arrow] *
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|Author:||Domac, Fusun Mayda; Misirli, Handan; Boylu, Ece; Ozer, Beratgul|
|Publication:||Turkish Journal of Endocrinology and Metabolism|
|Article Type:||Case study|
|Date:||Jun 1, 2009|
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