Fm 5 Flashcards
Signs and Symptoms of Hyperthyroidism (under 50 and over 70)
Hyperthyroidism presents with multiple symptoms that vary according to the age of the patient, the duration of the illness, the magnitude of hormone excess, and presence of comorbid conditions. Symptoms are related to the thyroid hormone’s stimulation of catabolism, and enhancement of sensitivity to catecholamines.
In patients under the age of 50, the most common signs and symptoms of hyperthyroidism are:
Heat intolerance (92%)
Tachycardia (96%) due to increased adrenergic tone and heightened conduction
Fatigue (84%)
Weight loss (50%) due to increased calorigenesis and gut motility causing hyperdefecation and malabsorption.
Tremor (84%)
Increased sweating (96%)
Exertional dyspnea caused by O2 consumption, CO2 production, and respiratory muscle weakness
Depression and hyperreflexia are less common but can be present.
Diarrhea and light periods can also occur with hyperthyroidism.
Many of the typical symptoms of hyperthyroidism are absent in patients older than age 70.
Patients who are older than 70 may present with sinus tachycardia (71%) and/or fatigue (56%), but they can also present with atrial fibrillation or weight loss, and no other symptoms.
Eye findings that can suggest hyperthyroidism 2
Exopthalmos (also called proptosis) is the forward projection or bulging of the eye out of the orbit. This is most commonly seen in Graves disease and can be either bilateral or unilateral.
How to Elicit Lid Lag
Ask the patient to follow your finger with their eyes; then move your finger slowly from their upper to lower field of vision. In lid lag, the upper eyelid lags behind the upper edge of the iris as the eye moves downward. Be careful when performing this maneuver; if your finger is moved too quickly, the diagnosis may be missed.
Causes of Enlarged Thyroid (Goiter) 7
Lack of iodine
Worldwide, the lack of iodine is the most common cause of goiter. In fact, iodine deficiency is the most common, yet easily preventable cause of developmental delay and mental retardation in the world. Areas that are the most affected are in northern Africa and Pakistan. Iodized salt is the easiest and least expensive way to supplement iodine.
Hypothyroidism
Hashimoto disease, which causes hypothyroidism, is a common cause of goiter.
Hyperthyroidism
Graves disease, which causes hyperthyroidism, also causes goiter. In fact, an enlarged thyroid can be seen in patients with too much, normal amounts or not enough thyroid hormone.
Nodules
Nodules, either single or multiple, can also cause an enlarged thyroid.
Thyroid cancer
Thyroid cancer is usually detected by palpating an enlarged, nodular thyroid.
Pregnancy
Pregnancy can occasionally cause a slight enlargement in the thyroid.
Thyroiditis
Thyroiditis can also cause an enlarged, often tender, thyroid gland.
Common Causes of Hyperthyroidism 5
Most common cause
Toxic diffuse goiter
Toxic diffuse goiter (Graves disease) accounts for the majority (60-80%) of hyperthyroidism.
Is an autoimmune disease caused by an antibody that acts at the thyroid-stimulating hormone (TSH) receptor and stimulates the gland to synthesize and secrete excess thyroid hormone.
Hypervascularity of the thyroid may result in a bruit or thrill upon auscultation that is not present in other etiologies of hyperthyroidism.
Exophthalmos is characteristic.
Pretibial myxedema, a rare finding, is most common in Graves disease and is caused by the deposition of hyaluronic acid in the dermis and subcutaneous tissues.
Toxic nodular goiter
Causes about 5% of cases of hyperthyroidism.
Thyroid nodules are common, but most are not symptomatic, and only 4% to 5% are cancerous.
Thyroid nodules are more common in patients over 40.
These older patients more often have multi nodular disease, whereas, solitary nodules are seen more often in younger patients and can be associated with iodine deficiency.
Evaluation:
Thyroid ultrasound and fine needle aspiration (FNA) biopsy of the nodules. Ultrasound-guided aspiration improves the diagnostic accuracy of the FNA.
Thyroiditis
Thyroid hormone leaks from an inflamed thyroid.
Happens after a viral illness or pregnancy.
Excessive iodine ingestion
Drug induced hyperthyroidism
Excessive iodine can occur through diet or a medication such as amiodarone, which can induce thyroiditis.
Studies to Determine the Etiology of Hyperthyroidism 2
Other studies
radioactive iodine taken up by the thyroid in the 24 hours following ingestion of a set dose. Normal RAIU uptake is 15% to 30% of the ingested dose. The various etiologies of hyperthyroidism can be differentiated as conditions that manifest as high RAIU (>30%) or low RAIU (<15%). For example, excess circulating thyroid hormone which occurs in Graves disease as a result of increased creation of thyroid hormone results in increased radioactive iodine uptake used to synthesize the thyroid hormone. Conversely, excess circulating thyroid hormone in subacute thyroiditis occurs as a result of the gland leaking excess hormone, so radioactive iodine uptake is low in this case, as more thyroid hormone is not synthesized. High RAIU (>30%)(every other dx is this) Low RAIU (<15%) Graves disease Sub-acute thyroiditis Multi-nodular goiter Silent thyroiditis Toxic solitary nodule Iodine induced TSH-secreting pituitary tumor Exogenous L-Thyroxine HCG secreting tumor Struma ovarii Amiodarone
Nodules that cause hyperthyroidism are hyperfunctioning and caused increased radioactive iodine uptake.
“Cold” (non-thyroxine producing) nodules can be caused by cancer although typically in that case hyperthyroidism is not present.
Diffuse increased uptake suggests Graves disease whereas a nodular pattern indicates a single nodule or multi nodular disease.
Anti-thyrotropin releasing antibodies (TRAb) are the pathologic mechanism for Graves disease and can be detected in the vast majority of patients with this condition. In patients with undiagnosed causes of hyperthyroidism, third-generation assays for TRAb are 97% sensitive and 99% specific for Graves. These antibodies are to be distinguished from anti-thryroid peroxidase (TPO) antibodies, which are elevated in 90% of patients with Hashimoto thryroiditis and 75% of patients with Graves.
Studies not used to determine the etiology of hyperthyroidism:
A thyroid ultrasound is used in the evaluation of thyroid nodules and thyroid enlargements but not hyperthyroidism. Ultrasound characteristics of a nodule can be used to stratify risk of malignancy and ultrasound can guide the fine needle aspiration of nodules that are not easily palpated. Ultrasound is starting to be used to differentiate Graves disease from other causes of hyperthyroidism when RAI scanning is not available or is contraindicated. Some experts predict that color-flow Doppler ultrasound may replace RAI scanning since it has similar accuracy but is safer, less costly and easier to administer.
An MRI of the thyroid gland is not necessary to diagnose hyperthyroid disease.
Eye Involvement in Graves Disease
The most common manifestations of Graves ophthalmopathy (eye problems) are eyelid retraction and exophthalmos.
Primary symptoms of the eye manifestations of Graves disease are related to corneal irritation from eyelid retraction.
While most of the time the eye signs and symptoms are bilateral, they can be unilateral.
While 50% of patients with Graves have some eye involvement by MRI, only about 20% to 30% of those are clinically relevant. In up to 10% the eye manifestations can happen when the patient is euthyroid or even hypothyroid. Treatment of hyperthyroidism does not affect the eye manifestations. In fact, some patients who get radioactive iodine will experience worsening symptomatology.
Treatment of Graves Disease 2
Medication to suppress thyroid hormone production:
1. Methimazole is the most commonly used medication to suppress thyroid hormone production.
Side effects are rare, but less than 1% of people who take methimazole have a serious side effect known as agranulocytosis in which the bone marrow stops producing white blood cells. This leaves patients vulnerable to serious infections. Contraindication in pregnancy.
It takes up to three months to suppress thyroid production, although patients usually start to notice improvement in their symptoms after one month.
Patients typically need to stay on medications for several years. More than half of patients return to hyperthyroidism if they try stopping medications.
The appropriate dose of medication fluctuates over time and people on medication need to come in for blood work often for adjustments. People on medication are more likely to have symptoms because fluctuations are hard to predict.
2. Oral dose of radioactive iodine:
Alternative to thyroid hormone suppressant medication. More commonly used in the United States.
Iodine concentrated in the thyroid and has very few side effects.
During the course of a few months the iodine destroys most of the overactive thyroid cells and the level of thyroid hormone falls and the thyroid gland shrinks in size.
Eventually most people who have this treatment start having too little thyroid in their bloodstream so that they need to start taking small doses of thyroid hormone to replace it.
Low thyroid is relatively easy to manage once you have found a dose where the patient feels normal and the TSH is in the normal range. Blood levels usually need to be drawn once or twice yearly and the dose of thyroid replacement usually stays about the same.
Contraindications:
Pregnancy and breast feeding are absolute contraindications.
May damage the fetal/infant thyroid.
Women are advised not to get pregnant for six months after a treatment and men are advised to not father children for four months after treatment.
Breast feeding should be discontinued permanently or until the next pregnancy.
Administration:
Patients with severe disease or younger patients may need more than one dose of RAI.
Patients with eye disease may get worsening of their eye disease with RAI. This can be prevented with administration of oral steroids after treatment.
Patients with severe hyperthyroidism should be treated with an antithyroid drug before and after RAI to prevent worsening of disease, and rarely thyroid storm.
Symptomatic tx of hyperthyroidism
Propranolol
Common Symptoms of Hypothyroidism 5
Weight gain, cold intolerance, pedal edema, heavy periods, and fatigue all arise from slowed metabolism. Fatigue is common to both hyper- and hypothyroidism.
