Thyrotoxicosis factitia is a rare disorder characterized by elevated levels of plasma thyroid hormones due to increased intake which can be iatrogenic, accidental, or intentional. Symptoms are similar to those in Grave's disease and diagnosis is based on history, examination findings, and by testing thyroid functions.
Presentation
Thyrotoxicosis factitia (TF) is also known as thyroxine addict or metabolic malingerer [1] [2] syndrome. It occurs in patients who are prescribed a very high dose of thyroid hormones as medication (iatrogenic); or those who consume thyroid hormone medication surreptitiously for weight loss or to increase their energy levels or to decrease sleep but deny taking the medication (intentional); or in children (accidental) or adults who consume meat containing thyroid tissue (accidental).
Clinical presentation of TF is identical to thyrotoxicosis except that patients with TF do not have a goiter (thyromegaly) and unlike patients with Grave's disease, they have neither exophthalmos nor myxedema (thickened skin over their shins). Features of thyrotoxicosis like anxiety, hyperactivity, increased perspiration, dyspnea, intolerance to heat, unexplained weight loss, diarrhea, fine tremors, hyperreflexia, tremulousness, palpitations and atrial fibrillation are seen in TF too. Complications like cardiac arrhythmias, hypermetabolism, hyperpyrexia, thyroid storm and myocardial infarction have been reported in TF [3] [4].
Entire Body System
- Goiter
goiter Inclusion term(s): Toxic nodular goiter NOS E05.20 Thyrotoxicosis with toxic multinodular goiter without thyrotoxic crisis or storm E05.21 Thyrotoxicosis with toxic multinodular goiter with thyrotoxic crisis or storm E05.3 Thyrotoxicosis from [icd10coded.com]
E05.00 Thyrotoxicosis with diffuse goiter without thyrotoxic crisis or storm E05.01 Thyrotoxicosis with diffuse goiter with thyrotoxic crisis or storm E05.1 Thyrotoxicosis with toxic single thyroid nodule E05.10 Thyrotoxicosis with toxic single thyroid [healthprovidersdata.com]
[…] elevated serum total and/or free thyroid hormone levels, undetectable serum thyrotropin levels, low/undetectable serum thyroglobulin concentration, normal urinary iodine excretion, low/suppressed thyroidal radioactive iodine uptake (RAIU), absence of goiter [ncbi.nlm.nih.gov]
Physical examination should take into consideration the patient's heart rate, basal metabolic rate, presence or absence of goiter, exophthalmos, and myxedema. [symptoma.com]
Classification of goiter includes simple nontoxic goiter, colloid goiter, MNG, and SNT. Follicular carcinomas, Hurthle cell carcinoma with their treatment are discussed. [jaypeedigital.com]
- Weight Loss
It occurs in patients who are prescribed a very high dose of thyroid hormones as medication (iatrogenic); or those who consume thyroid hormone medication surreptitiously for weight loss or to increase their energy levels or to decrease sleep but deny [symptoma.com]
Classic symptoms of hyperthyroidism tachycardia usually sinus a fib common too sweating/feeling warm poor sleep weight loss possible fine tremor eye signs (Graves only) Causes of these symptoms usually Graves disease in the west toxic multinodular goitre [emergencymedicineireland.com]
Accidental overdose has been reported in people taking weight-loss supplements that contain T3 and T4. Exogenous hyperthyroidism can lead to bone loss and cardiac dysfunction, including arrhythmia, heart failure, and myocardial infarction. [visualdx.com]
Features of MyAccess include: Remote Access Favorites Save figures into PowerPoint Download tables as PDFs Go to My Dashboard Close Sweating, weight loss or gain, anxiety, palpitations, loose stools, heat intolerance, fatigue, menstrual irregularity Tachycardia [accessmedicine.mhmedical.com]
Thyroid hormone abuse should be considered in all patients with unexplained sinus tachycardia, especially in those who take thyroid hormone to promote weight loss. [academic.oup.com]
- Thyroid Nodule
[…] with toxic uninodular goiter E05.10 Thyrotoxicosis with toxic single thyroid nodule without thyrotoxic crisis or storm E05.11 Thyrotoxicosis with toxic single thyroid nodule with thyrotoxic crisis or storm E05.2 Thyrotoxicosis with toxic multinodular [icd10coded.com]
nodule E05.10 Thyrotoxicosis with toxic single thyroid nodule without thyrotoxic crisis or storm E05.11 Thyrotoxicosis with toxic single thyroid nodule with thyrotoxic crisis or storm E05.2 Thyrotoxicosis with toxic multinodular goiter E05.20 Thyrotoxicosis [healthprovidersdata.com]
[…] and metabolic diseases Blocks Disorders of thyroid gland Similars E05.0 - Thyrotoxicosis with diffuse goitre E05.1 - Thyrotoxicosis with toxic single thyroid nodule E05.2 - Thyrotoxicosis with toxic multinodular goitre E05.3 - Thyrotoxicosis from ectopic [icd-code.org]
nodule E05.10 …… without thyrotoxic crisis or storm E05.11 …… with thyrotoxic crisis or storm E05.2 Thyrotoxicosis with toxic multinodular goiter E05.20 …… without thyrotoxic crisis or storm E05.21 …… with thyrotoxic crisis or storm E05.3 Thyrotoxicosis [icd10data.com]
nodule without thyrotoxic crisis or storm; E05.11 - Thyrotoxicosis with toxic single thyroid nodule with thyrotoxic crisis or storm; E05.20 - Thyrotoxicosis with toxic multinodular goiter without thyrotoxic crisis or storm; E05.21 - Thyrotoxicosis with [medicaid.ncdhhs.gov]
- Fever
Fever should not be treated with cooling mattresses, and Tylenol is ineffective. Fever may be controlled with Demerol (25-50 mg intravenously Q 6 hours) and chlorpromazine (25-50 mg intravenously Q 6 hours). [thebigl.co]
In subacute (De Quervain's) thyroiditis symptoms patients may have fever in the initial phase and the thyroid is tender. [jiscmail.ac.uk]
Agranulocytosis occurs in 1 in 300 patients treated with thionamides and presents as a sore throat, mouth ulcers and high fever. [statpearls.com]
It usually causes fever and pain in the neck, jaw or ear. [nhs.uk]
Rarely, methimazole or propylthiouracil may cause fever, sore throat, or other signs of infection. If you develop these symptoms, contact your doctor immediately. [medicinenet.com]
- Heat Intolerance
Signs and symptoms vary between people and may include irritability, muscle weakness, sleeping problems, a fast heartbeat, heat intolerance, diarrhea, enlargement of the thyroid, and weight loss. [dbpedia.org]
Features of MyAccess include: Remote Access Favorites Save figures into PowerPoint Download tables as PDFs Go to My Dashboard Close Sweating, weight loss or gain, anxiety, palpitations, loose stools, heat intolerance, fatigue, menstrual irregularity Tachycardia [accessmedicine.mhmedical.com]
They may include Being nervous or irritable Mood swings Fatigue or muscle weakness Heat intolerance Trouble sleeping Hand tremors Rapid and irregular heartbeat Frequent bowel movements or diarrhea Weight loss Goiter, which is an enlarged thyroid that [icdlist.com]
In Europe, it affects around 1 in 2000 people annually. 1 Although thyrotoxicosis typically presents with weight loss, heat intolerance, and palpitations, there are a large variety of additional features, which manifest more variably with advancing age [doi.org]
Gastrointestinal
- Diarrhea
Features of thyrotoxicosis like anxiety, hyperactivity, increased perspiration, dyspnea, intolerance to heat, unexplained weight loss, diarrhea, fine tremors, hyperreflexia, tremulousness, palpitations and atrial fibrillation are seen in TF too. [symptoma.com]
Signs and symptoms vary between people and may include irritability, muscle weakness, sleeping problems, a fast heartbeat, heat intolerance, diarrhea, enlargement of the thyroid, and weight loss. [dbpedia.org]
They may include Being nervous or irritable Mood swings Fatigue or muscle weakness Heat intolerance Trouble sleeping Hand tremors Rapid and irregular heartbeat Frequent bowel movements or diarrhea Weight loss Goiter, which is an enlarged thyroid that [icdlist.com]
- Increased Appetite
appetite Hyperactivity / irritability Heat intolerance Tremor Sweating Palpitations Diarrhoea Amenorrhoea Alopecia Signs Sinus tachycardia / atrial fibrillation Psychomotor agitation Fine tremor Warm skin Onycholysis Palmar erythema Muscle wasting / [medschool.co]
appetite Hyperkinesia Sweating Heat intolerance Palpitations Tremor Irritability Oligomenorrhoea Infertility Psychosis, panic Lost libido Tall kids Grave's only eye signs pretibial myoedema Grave's demopathy thyroid acropachy extreme cases; soft tissue [alancam.com]
Signs and symptoms of hyperthyroidism include: Nervousness Irritability Increased appetite Heart palpitations Heat intolerance Signs and symptoms of hypothyroidism include: Mental sluggishness Depressed mood Weight gain Decreased heart rate Increased [medicinenet.com]
These can include diarrhoea, weight loss (although around 10% develop weight gain due to increased appetite), shaking or tremor (notably in the hands), sweating, increased heart rate that can be felt by the patient (palpitations), overactivity, agitation [yourhormones.info]
Presentation of thyrotoxicosis Presentation of thyrotoxicosis Symptoms Weight loss despite an increased appetite. Increased or decreased appetite. Irritability. Weakness and fatigue. Diarrhoea +/- steatorrhoea. Sweating. Tremor. [gponline.com]
Cardiovascular
- Tachycardia
Other types of arrhythmias can be sinus tachycardia, ventricular tachycardia, SVT, ventricular fibrillation and rarely cardiac arrest can also happen [Citation13–Citation15]. [tandfonline.com]
Other types of arrhythmias can be sinus tachycardia, ventricular tachycardia, SVT, ventricular fibrillation and rarely cardiac arrest can also happen [13–15]. [ncbi.nlm.nih.gov]
Musculoskeletal
- Muscle Weakness
This case highlights the potential for thyrotoxicosis factitia to exacerbate hypokalaemia and muscle weakness from other causes in bodybuilders presenting with acute severe weakness, irrespective of ethnicity. [edm.bioscientifica.com]
Signs and symptoms vary between people and may include irritability, muscle weakness, sleeping problems, a fast heartbeat, heat intolerance, diarrhea, enlargement of the thyroid, and weight loss. [dbpedia.org]
weakness, muscle cramps, hyperreflexia Tetany (rare) Thyroid Goiter (often with a bruit) in Graves disease Moderately enlarged, tender thyroid in subacute thyroiditis Eye Upper eyelid retraction Stare and lid lag with downward gaze Thyroid associated [accessmedicine.mhmedical.com]
They may include Being nervous or irritable Mood swings Fatigue or muscle weakness Heat intolerance Trouble sleeping Hand tremors Rapid and irregular heartbeat Frequent bowel movements or diarrhea Weight loss Goiter, which is an enlarged thyroid that [icdlist.com]
Psychiatrical
- Mood Swings
They may include Being nervous or irritable Mood swings Fatigue or muscle weakness Heat intolerance Trouble sleeping Hand tremors Rapid and irregular heartbeat Frequent bowel movements or diarrhea Weight loss Goiter, which is an enlarged thyroid that [icdlist.com]
- Denial
We are receiving denials that this provider type may not bill for t... [ Read More ] Are there new CMS CCI edits for billing out 93312, 93320 & 93325 for anesthesiologists. We are getting denials from all insurance providers when we bill for these. [coder.aapc.com]
Neurologic
- Tremor
Features of thyrotoxicosis like anxiety, hyperactivity, increased perspiration, dyspnea, intolerance to heat, unexplained weight loss, diarrhea, fine tremors, hyperreflexia, tremulousness, palpitations and atrial fibrillation are seen in TF too. [symptoma.com]
Sweating Palpitations Diarrhoea Amenorrhoea Alopecia Signs Sinus tachycardia / atrial fibrillation Psychomotor agitation Fine tremor Warm skin Onycholysis Palmar erythema Muscle wasting / weakness Hyperreflexia Alopecia Gynaecomastia Manifestations of [medschool.co]
Access Favorites Save figures into PowerPoint Download tables as PDFs Go to My Dashboard Close Sweating, weight loss or gain, anxiety, palpitations, loose stools, heat intolerance, fatigue, menstrual irregularity Tachycardia; warm, moist skin; stare; tremor [accessmedicine.mhmedical.com]
Classic symptoms of hyperthyroidism tachycardia usually sinus a fib common too sweating/feeling warm poor sleep weight loss possible fine tremor eye signs (Graves only) Causes of these symptoms usually Graves disease in the west toxic multinodular goitre [emergencymedicineireland.com]
They may include Being nervous or irritable Mood swings Fatigue or muscle weakness Heat intolerance Trouble sleeping Hand tremors Rapid and irregular heartbeat Frequent bowel movements or diarrhea Weight loss Goiter, which is an enlarged thyroid that [icdlist.com]
- Irritability
Signs and symptoms vary between people and may include irritability, muscle weakness, sleeping problems, a fast heartbeat, heat intolerance, diarrhea, enlargement of the thyroid, and weight loss. [dbpedia.org]
If you are thyrotoxic, you may feel nervous or irritable, because all of your body’s functions are speeding up. [virginiamason.org]
They may include Being nervous or irritable Mood swings Fatigue or muscle weakness Heat intolerance Trouble sleeping Hand tremors Rapid and irregular heartbeat Frequent bowel movements or diarrhea Weight loss Goiter, which is an enlarged thyroid that [icdlist.com]
iodine Pregnancy-related - hyperemesis gravidarum, hydatidiform mole Struma ovarii Congenital hyperthyroidism Secondary TSH-secreting pituitary tumour Manifestations Clinical Features Symptoms Weight loss despite increased appetite Hyperactivity / irritability [medschool.co]
- Hyperreflexia
Features of thyrotoxicosis like anxiety, hyperactivity, increased perspiration, dyspnea, intolerance to heat, unexplained weight loss, diarrhea, fine tremors, hyperreflexia, tremulousness, palpitations and atrial fibrillation are seen in TF too. [symptoma.com]
Hyperactivity / irritability Heat intolerance Tremor Sweating Palpitations Diarrhoea Amenorrhoea Alopecia Signs Sinus tachycardia / atrial fibrillation Psychomotor agitation Fine tremor Warm skin Onycholysis Palmar erythema Muscle wasting / weakness Hyperreflexia [medschool.co]
and testicular malignancies may cause hyperthyroidism Heat intolerance, sweating Palpitations Pruritus Frequent bowel movements Weight loss (or gain) Menstrual irregularities Nervousness, fine resting tremor Fatigue Muscle weakness, muscle cramps, hyperreflexia [accessmedicine.mhmedical.com]
Her physician found no obvious tremors, hyperdynamic apex, or hyperreflexia on physical exam. To rule out laboratory error from the second set of tests, her physician ordered yet another round of blood work. [mdedge.com]
- Lethargy
Definition - Dry skin - Cold intolerance - Weight gain - Constipation - Weakness - Lethargy - Fatigue - Muscle cramps - Myalgia/stiffness - Lack of ambition or energy - In children, growth retardation Physical signs: coarse skin/hair, cold/dry skin, periorbital [flashcardmachine.com]
S. no Author Age /Se x Presentation T3, T4, TSH Comorbids EKG Echo Treatment Outco me FU 1 Bacci V et al [4] 63/F Lethargy, Unconsciou sness T4 1.2 ug/dL Hypothyroidism NSST LV dilatation Resuscitation Death N/A 2 Hack JB et al [5] 34/M Vomiting, Diaphoresis [ncbi.nlm.nih.gov]
- Stupor
Because of her stuporous mental state and acute respiratory failure, she was intubated and treated in the intensive care unit. [unboundmedicine.com]
Apathy, stupor and coma may occur. Laboratory evaluation of thyrotoxicosis begins with a measurement of TSH. If TSH is suppressed ( Figure 1. [ocw.tufts.edu]
Workup
The initial diagnosis of TF is based on clinical suspicion. A detailed history is essential to determine medicine intake, diet, the degree of symptom progression and underlying psychiatric issues. Physical examination should take into consideration the patient's heart rate, basal metabolic rate, presence or absence of goiter, exophthalmos, and myxedema. Laboratory biochemical tests are required to determine total triiodothyronine (T3), total thyroxine (T4), thyroid-stimulating hormone (TSH), TSH receptor, and thyroglobulin level. An elevated free thyroxine index (ratio of T-4 to T-3) [5], diminished thyroglobulin level [6] with an increased basal metabolic rate are diagnostic of TF. Patients with a positive TSH receptor and hyperthyroidism can be misdiagnosed as Grave's disease [7]. To distinguish TF from other causes of thyrotoxicosis, fecal thyroxine levels can be obtained with elevated levels confirming the diagnosis of TF [8].
An imaging study like color doppler ultrasonography is also useful to diagnose TF as it demonstrates the lack of thyroid blood flow [9]. If a patient has an elevated free thyroid hormone level with low TSH levels but is not able to provide a history of ingesting thyroid hormones, a radioactive iodine I-123 uptake is indicated and a low uptake is suggestive of TF [10].
A psychiatrist referral must be considered to exclude Munchausen syndrome [11] and other psychiatric disorders.
Other Test Results
- Increased Basal Metabolic Rate
Physical examination should take into consideration the patient's heart rate, basal metabolic rate, presence or absence of goiter, exophthalmos, and myxedema. [symptoma.com]
[…] hormone affects almost every tissue and organ system in the body by increasing basal metabolic rate and tissue thermogenesis. [statpearls.com]
ACTIONS OF THYROID HORMONE • Increases oxygen consumption • Increases carbohydrate and lipid catabolism • Stimulates protein synthesis • Increases basal metabolic rate • Increases thermogenesis • Increases expression of the low-density lipoprotein (LDL [quizlet.com]
Treatment
This chapter will focus on the prevalence, consequences and the treatment of the thyrotoxicosis factitia, as a complication of inappropriate L- thyroxine treatment for obesity, following the ingestion of beef contaminated with thyroid gland and after [iris.unina.it]
There is controversy about the treatment of mild (subclinical) hypothyroidism. Generally, benefits of treatment are clearest in younger populations. [accesspharmacy.mhmedical.com]
Radio Active Iodine treatment – RAI Rx. 4. Thyroidectomy – Subtotal or Total 5. NSAIDs and Corticosteroids – for SAT 12. www.drsarma.in Symptom Relief 1. [slideshare.net]
Treatment of iodine-induced thyrotoxicosis is complex because an iodine-enriched thyroid makes treatment with 131I unfeasible for several weeks and reduces the efficacy of ATD treatment. [scielo.br]
Prognosis
Historical Perspective Classification Pathophysiology Causes Differentiating Thyrotoxicosis factitia from Other Diseases Epidemiology and Demographics Risk Factors Screening Natural History, Complications, and Prognosis Natural History Complications Prognosis [wikidoc.org]
After defining the dysfunction or disease, the text presents the epidemiology, etiopathogenesis, clinical features, first and second level tests for diagnosis, first and second line therapies, prognosis, and recommendations for follow-up. [books.google.com]
Exams and Tests Blood tests used to diagnose factitious hyperthyroidism include: Free T4 Radioactive iodine uptake Thyroglobulin Total T3 Total T4 TSH Outlook (Prognosis) Factitious hyperthyroidism will clear up on its own when you stop taking or lower [health.firstlighthealthsystem.org]
Etiology
Certain conditions have both an underlying etiology and multiple body system manifestations due to the underlying etiology. [icd10coded.com]
These findings well correlate with the etiology of thyrotoxicosis factitia and may represent an additional, useful tool to confirm the diagnosis. [ncbi.nlm.nih.gov]
Etiology In the United States and most western countries, Graves disease is the most common cause of hyperthyroidism. As Graves disease is autoimmune in etiology, this form of hyperthyroidism tends to manifest itself in younger populations. [statpearls.com]
Etiology, Pathogenesis, and Pathology 20. [slideshare.net]
Epidemiology
After defining the dysfunction or disease, the text presents the epidemiology, etiopathogenesis, clinical features, first and second level tests for diagnosis, first and second line therapies, prognosis, and recommendations for follow-up. [books.google.com]
Historical Perspective Classification Pathophysiology Causes Differentiating Thyrotoxicosis factitia from Other Diseases Epidemiology and Demographics Risk Factors Screening Natural History, Complications, and Prognosis Natural History Complications Prognosis [wikidoc.org]
Epidemiology 1% of the population peak incidence 30-50y F>M Most common cause of endogenous hyperthyroidism Aetiology Unknown Genetic predisposition: HLA-DR3, -B8, DR2 CTLA-4 polymorphisms Potentially environmental factors: viral or bacterial infection [alancam.com]
Pathophysiology
من الصفحات Werner & Ingbar’s The Thyroid: A Fundamental and Clinical Text, 10th Edition has been extensively revised and streamlined to deliver the most comprehensive coverage of the thyroid including anatomy, development, biochemistry, physiology, pathophysiology [books.google.com]
University of Thessaloniki Hipokratio Hospital, Thessaloniki, Greece Summary Clinical nuclear medicine has been developed in parallel with thyroidology, providing sophisticated diagnostic and therapeutic methods and a deep insight into thyroid physiology and pathophysiology [nuclmed.gr]
Historical Perspective Classification Pathophysiology Causes Differentiating Thyrotoxicosis factitia from Other Diseases Epidemiology and Demographics Risk Factors Screening Natural History, Complications, and Prognosis Natural History Complications Prognosis [wikidoc.org]
912 páginas Werner & Ingbar’s The Thyroid: A Fundamental and Clinical Text, 10th Edition has been extensively revised and streamlined to deliver the most comprehensive coverage of the thyroid including anatomy, development, biochemistry, physiology, pathophysiology [books.google.es]
Prevention
Categories M.D.C MDC Category Not Assigned For This ICD Code E05.4 Medicare Severity-Diagnosis Related Groups MS-DRG MS-DRG Category Not Assigned For This ICD Code E05.4 Clinical Classifications Software CCS CCS Category Not Assigned For This ICD Code E05.4 Prevention [medicbind.com]
Iatrogenic hyperthyroidism may be intentional (e.g., patients with thyroid cancer who have clinicopathologic parameters that warrant thyroid-stimulating hormone suppression to prevent cancer recurrence) or inadvertent (e.g., an excessive dose of thyroid [aafp.org]
This indicates that thyroid suppression with thyroid hormone may be ineffective in preventing this disease. Two patients were treated by subtotal thyroidectomy because of recurrent or prolonged episodes of SRH. [jamanetwork.com]
Rapidly find the answers you need with separate sections on diseases and disorders, differential diagnosis, clinical algorithms, laboratory results, and clinical preventive services, plus an at-a-glance format that uses cross-references, outlines, bullets [books.google.com]
Natural History, Complications, and Prognosis Natural History Complications Prognosis Diagnosis Diagnostic Criteria History and Symptoms Physical Examination Laboratory Findings Imaging Findings Other Diagnostic Studies Treatment Medical Therapy Surgery Prevention [wikidoc.org]
References
- Harvey RF. Thyroxine ‘‘addicts.’’ Br Med J (Clin Res Ed). 1973;2:35–36.
- Gorman CA, Wahner HW, Tauxe WN. Metabolic malingerers: patients who deliberately induce or perpetuate a hypermetabolic or hypometabolic state. Am J Med. 1970;48:708–714.
- Yoon SJ, Kim DM, Kim JU, et al. A case of thyroid storm due to thyrotoxicosis factitia. Yonsei Med J. 2003;44 :351–354.
- Locker GJ, Kotzmann H, Frey B, et al. Factitious hyperthyroidism causing acute myocardial infarction. Thyroid. 1995;5:465–467.
- Pearce EN. Diagnosis and management of thyrotoxicosis. BMJ. 2006 Jun 10; 332 (7554): 1369 -1379
- Mariotti S, Martino E, Cupini C, et al. Low serum thyroglobulin as a clue to the diagnosis of thyrotoxicosis factitia. N Engl J Med. 1982;307:410–412.
- Jahagirdar VR, Strouhal P, Holder G, Gama R, Singh BM. Thyrotoxicosis factitia masquerading as recurrent Graves’ disease: Endogenous antibody immunoassay interference, a pitfall for the unwary. Ann Clin Biochem. 2008; 45: 325-7
- Bouillon R, Verresen L, Staels F, Bex M, De Vos P, De Roo M. The measurement of fecal thyroxine in the diagnosis of thyrotoxicosis factitia. Thyroid. 1993;3:101–103.
- Bogazzi F, Bartalena L, Vitti P, Rago T, Brogioni S, Martino E. Color flow Doppler sonography in thyrotoxicosis factitia. J Endocrinol Invest. 1996;19: 603–606.
- Braverman LE. Evaluation of thyroid status in patients with thyrotoxicosis. Clin Chem. 1996;42:174–178
- Mittra ES, Niederkohr RD, Rodriguez C, et al. Uncommon causes of thyrotoxicosis. J Nucl Med 2008; 49:265-278