Hyperthyroidism
Definition:
An increase in the circulating thyroid hormones (T3 & T4) due to an increase in its synthesis with a decrease in TSH levels.
Types:
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Primary (caused by conditions related to the thyroid gland).
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Secondary (caused by extra-thyroidal conditions like pituitary gland).
Causes:
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Primary causes: (MOST COMMON)
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Graves disease:
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Most common cause of hyperthyroidism.
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Autoimmunity.
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Caused by thyroid stimulating immunoglobulin (IgG Autoantibody), which binds to the thyroid stimulating hormone receptor (TSH) and induces thyroid hormone synthesis and secretion.
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Nodular goiter:
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Typically in patients over 40 years.
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Enlarged glands with mono or multi nodules.
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If “autonomous” hyperactivity of follicular cells is present → toxic goiter (rare).
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Two types:
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Multinodular (Plummer disease).
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Solitary nodule:
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Thyroiditis
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Viral
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Lymphatic
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Postpartum
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Iodine-induced: excess iodine ingestion from diet, radiographic contrast or medication.
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Secondary causes:
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Pituitary tumor.
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Others:
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Factitious hyperthyroidism:
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Excessive thyroid hormone ingestion (e.g. levothyroxine).
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Seen in patients who attempt suicide or want to lose weight.
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Ovarian tumor (struma ovarii) produce thyroid hormone.
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Metastatic thyroid cancer.
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Symptoms:
All symptoms are mainly caused due to increased basal metabolic rate.
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Nervousness, insomnia, irritability
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Hand tremor, hyperactivity
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Sweating
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Heat intolerance
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Increase in appetite, weight loss
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Palpitation
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Diarrhea
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Proximal muscle weakness
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Menorrhagia # hypothyroidism (oligomenorrhea)
Signs:
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Brisk reflex
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Tremor
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Increase in BP
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Goiter (diffused, non tender → graves | tender → thyroiditis| irregular,
asymmetrical → multinodular| single nodule w\ atrophic thyroid → toxic adenoma) -
Tachycardia, arrhythmia (PVC, Atrial fibrillation)
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Specific signs seen in Graves:
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Proptosis (hallmark of graves), lid lag and retraction
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Pretibial edema
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Carotid bruit
Only Graves’s disease of the hyperthyroidism types has eye and skin abnormalities.


Study guide:
Hyperthyrodism
Exopthalmos & Dermopathy
Diffused Goitter
Diagnosis:
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Best initial/most useful screening test is measuring serum TSH level.

Treatment:

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Antithyroid drugs (ATD):
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Methimazole.
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Propylothiouracel (PTU): can be used in pregnancy.
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Indications:
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Mostly in graves → with pregnant women, children, and those who refuse RAI.
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Side effects:
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Polyarthritis
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Agranulocytosis.
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Immunological hepatitis (with PTU).
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Methimazole is preferred more than PTU in general except in pregnancy.
Agranulocytosis:
patients on anti- thyroid drug should be told to stoptheintakein case of fever or sore throat.
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Radioactive iodine (RAI):
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Indications:
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Treatment of choice in grave’s disease.
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ATD relapses or if the patient develops agranoulocytosis.
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Elderly.
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Multinodular and solitary nodule.
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Cardiac problems: treatment with methimazole first is recommended.
Methimazole should be stopped before starting RAI by 4 days.
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Side effect:
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Hypothyroidism (major complication).
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Could exacerbate proptosis.
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Could cause thyroiditis.
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Contraindication:
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Pregnancy or breastfeeding, if taken avoid pregnancy for 4-8 months.
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Surgery (total removal is preferred):
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Indications:
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Patient < 40 Y/O with toxic nodules.
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Pregnant women and children who cannot tolerate ATD.
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Side effect:
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Hypothyroidism
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Risk of recurrent laryngeal nerve injury.
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Watch for hypocalcaemia → risk of parathyroid gland removal.
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Symptomatic treatment:
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In palpitation: Beta blocker is used with ATD
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Graves ophthalmopathy:
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Steroids are the best initial therapy.
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Follow up:
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ATD:
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Patient on ATD should be monitored every 4-12 weeks until reaching euthyroid. (4-week check-upàcheck T4 b/c TSH ‘short half-life’ will not respond until 6 weeks).
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If euthyroid is accomplished → check every 3-4 months for 12-18 months.
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If medication is ceased → every 3-4 months to look for relapses.
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RAI:
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Every 4-6 weeks for 3 months.
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Then annual visits to check for hypothyroidism.
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References:
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Agabegi S, Agabegi E, Ring A. Step-up to medicine. Philadelphia: Wolters Kluwer/Lippincott Williams & Wilkins; 2013.
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Aafp.org. Thyroid and Parathyroid Disorders - American Family Physician [Internet]. 2015 [cited 23 December 2015]. Available from: http://www.aafp.org/afp/topicModules/viewTopicModule.htm?topicModuleId=67
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Lipsky M, King M. Blueprints family medicine. Baltimore, MD: Lippincott Williams & Wilkins; 2011.
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Sattar H. Fundamentals of pathology. Chicago: Pathoma.com; 2011.
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Kaplan. Kaplan lecture notes, Medicine, 2014.
Written by: Rawan Al-Tuwaijri
Revised by: Jumana AlJohani
Bassam Alghamdi
Format Editor: Adel Yasky
Web publisher: Bayan Alzomaili