Diffuse Toxic Goiter

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Background

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This condition was first described by the English physician Caleb H. Parry (1755-1822). The disorder is known as Graves disease (after Robert J. Graves) in the English-speaking world and as Basedow disease (after Karl A. von Basedow) in the rest of Europe.

In diffuse toxic goiter, the thyroid gland is diffusely hyperplastic and excessively overproduces thyroid hormone. This results in accelerated metabolism in most body organs. The clinical response and its manifestations are variable in intensity, distribution, and are modified by age, gender, and associated premorbid medical problems. When the diffuse toxic goiter is associated with clinical evidence of oculopathy, or rarely with dermopathy/acropachy, the term Graves’ disease is often applied. Awareness is needed regarding the atypical clinical presentations.

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Pathophysiology

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The thyroid gland is usually enlarged to a variable degree
thyroid follicular cells are hypertrophic and hyperplastic,
Lymphocytes and plasma cells infiltrate into the thyroid gland and may aggregate into lymphoid follicles.

autoimmune disorder whereby the thyroid gland is overstimulated by antibodies directed to the thyroid-stimulating hormone (TSH) receptor on the thyroid follicular cells.
This antibody stimulates iodine uptake, thyroid hormonogenesis and release, and thyroid gland growth.
Although mainly produced within the thyroid gland, these antibodies reach the circulation and can be measured by various assays in most, but not all, cases.

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Epidemiology

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0.2 new cases per 1000 per year.

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Mortality

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Mortality is rare but is due to cardiovascular problems such as heart failure, arrhythmias, or myocardial infarction. Debility and infection may occur. Thyroid storm is rare but may be fatal from dehydration, hyperthermia, and organ failure.

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Morbidity

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increased bone turnover and osteoporosis, especially in postmenopausal women, or from atrial fibrillation and its sequelae, such as thromboembolism, especially in older men. Personality changes and psychopathology, muscular weakness, and systemic symptoms all lead to quality of life changes.

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Symptoms

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• Hypermetabolism with heat generation and protein catabolism - Weight loss with good appetite, heat intolerance, sweating, muscle weakness (proximal more than distal), osteoporosis
• Adrenergic - Palpitations, tremor, emotional lability, insomnia, restlessness, hyperdefecation
• Other - Gynecomastia, lighter menses, insomnia, decreased concentration, fatigue, shortness of breath on exertion, and decreased exercise tolerance
• Goiter - May be mildly tender, may have difficulty swallowing if large
• Associated oculopathy (clinically present in about 25% of cases) - Tearing, pain, puffiness, grittiness, double vision, prominent appearance, rarely visual loss

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Physical

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Hypermetabolism with protein catabolism - Warm hands, often with heat radiation, velvety skin, proximal muscle weakness in the arms and legs compared with distal muscle strength
Hyperadrenergic - Bounding and fast pulse, wide pulse pressure with higher systolic and lower diastolic blood pressure, active precordium and abdominal aorta to palpation; lid retraction (upper eyelid more than halfway from pupil to top of iris) and lid lag or globe lag, tremor of fingers, brisk reflexes
Organ decompensation - Atrial fibrillation, congestive heart failure, jaundice
Oculopathy - Periorbital puffiness, chemosis, conjunctival redness, proptosis (sclera visible below iris), double vision with eye movements, loss of color vision (rare), or papilledema (rare)
Thyroid gland - Mildly enlarged (but may be normal in size, many times normal in size, or difficult to palpate); smooth, rubbery firm in texture; nontender or mildly tender; systolic bruit on auscultation
Miscellaneous - Pretibial myxedema (uncommon), rare may be finger clubbing, diffuse lymphadenopathy, and splenomegaly

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Causes

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Diffuse toxic goiter and its hyperthyroidism are caused by TSH-receptor stimulating antibodies.
genetic lack of suppressor T cells that results in the unregulated production of the antibody
Predisposing factors include genetic susceptibility (including HLA factors); female gender; mental stress; viral infection; surgery; postpartum state; iodine administration; drugs such as lithium and iodine-containing agents, such as amiodarone, interferons and interleukins, and antiretroviral agents.

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Laboratory Studies

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Serum TSH
Serum free thyroxin (T4), or equivalent test, that compensates for any changes in thyroid-binding globulin. If levels are elevated, then hyperthyroidism is diagnosed. Levels will be in the normal range in about 5% of cases.
The presence of ophthalmopathy indicates the diagnosis, and no more diagnostic testing is needed regarding the cause of the hyperthyroidism.

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Hyperthyreose Symptome

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Tachykardie, Palpitation, Vorhofflimmern, hohe RR-Amplitude
Beschleunigte Passage, Durchfall
Wärmeintoleranz, Temperaturerhöhung, Cholesterin erniedrigt
Haut warm, feucht, gut durchblutet
Nervosität, innere Unruhe, Reizbarkeit
Unkonzentriertheit, Rastlosigkeit
Tremor, Reflex-steigerung
Myopathie: Atrophie der proximalen Muskel-gruppen (Schulter-, Beckengürtel)
Einschränkung von Potenz und Fertilität

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Untersuchungen

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Standard
• Anamnese
• Klinische Untersuchung
• TSH, fT4 (fT3)
• Ultraschall
• Serum-Kalzium
• Laryngoskopie
Spezielle Untersuchungen
• Röntgen: Thorax in 2 Ebenen
• Szintigramm (unter Suppressionsbedingung)
• Tracheaziel, Valsalva
• CT, MRT
• Punktionszytologie
• Autoantikörper (TRAK, TAK, MAK)
• Kalzitonin basal + ggf. stimuliert, CEA, Thyreoglobulin

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Operationsvorbereitung bei Hyperthyreose

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Thiamazol (Methimazol) 15-20 mg/d (5 mg) > 6 Wochen
Carbimazol (Thiamazol) 20-40 mg/d (5-10mg) > 6 Wochen
Propylthiouracil 150-300 mg/d (50 mg) > 4 Wochen
Plummerung 3 × 15-30 Tropfen/d 7-10 Tage; nicht über 14 Tage
Betablocker (Propranolol) 120-160 mg/d 5-10 Tage und 5 Tage postop.

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Operative und postoperative Komplikationen

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Eine Operationssterblichkeit (Letalität) besteht heute angesichts schonender Allgemeinnarkose und verlässlicher Vorbereitung bei Hyperthyreose so gut wie nicht mehr. Ausnahmen stellen allenfalls Notfalleingriffe an älteren Menschen mit Erstickungsgefahr infolge Trachealkompression dar.
Mit einer einseitigen Stimmbandlähmung (= Rekurrensparese) ist in ca. 0,2 bis 3% der Fälle zu rechnen. Bei der Operation einer Struma maligna oder Rezidivstruma muss ggf. eine höhere Risikorate in Kauf genommen werden (generell 5- bis 10fach erhöht).
Der Hypoparathyreoidismus (Tetanie) wegen partieller oder totaler Mitentfernung der Epithelkörperchen ist außerordentlich selten und bei weniger als 0,5% der Fälle gutartiger Schilddrüsenoperationen zu erwarten, bei radikaler Thyreoidektomie mit über 3% deutlich häufiger.
Die Risiken für Nebenschilddrüsen und Rekurrensnerven können heute durch operativ-präparatorische Darstellung der Strukturen unter Sichtkontrolle maßgeblich verringert werden.
Mit einer Hypothyreose ist je nach Art der Schilddrüsenerkrankung und Ausdehnung der erforderlichen Resektion in 5 bis über 50% der Fälle zu rechnen. Die postoperative Hypothyreose nach besonders ausgedehnter Resektion ist wie jede andere Schilddrüsenunterfunktion lebenslang mit Schilddrüsenhormon zu substituieren (z.B. 75-150 μg T4 tgl.). Die Hormonverordnung mit Jodbeimengung dient nach beidseitigen Resektionen gleichzeitig der Rezidivprophylaxe. Bei ausreichend erhaltenen Drüsenresten von etwa normaler Größe gewährleistet auch die tägliche Jodeinnahme von 100-200 μg eine normale Funktion und Rückfallverhütung.