Hypothyroidism (myxedema coma), 244.9
Thyroid storm (thyrotoxic crisis), 242.91
HYPERTHYROIDISM (THYROTOXICOSIS)
I. Definition
A condition of excess secretion of thyroxine (T4) and triiodothyronine (T3) resulting from a variety of clinical disorders
II. Etiology/predisposing factors/incidence
A. Graves’ disease—the most common cause; associated with goiter and ocular changes
B. Subacute thyroiditis
C. Thyroid-stimulating hormone (TSH) pituitary tumor
D. Toxic nodular goiter or thyroid carcinoma
E. Other autoimmune causes:
1. Pernicious anemia
2. Diabetes mellitus
3. Myasthenia gravis
F. Most commonly seen between ages of 20 and 40
G. Higher incidence among women; 8:1 female-to-male ratio
H. May also occur in patients on high-dose amiodarone (Cordarone) therapy. Note: High-dose amiodarone therapy may also cause signs of hypothyroidism.
III. Subjective/physical examination findings (thyrotoxic manifestations)
A. Hypermetabolism
B. Heat intolerance
C. Fatigue
D. Anxiety
E. Nervousness
F. Manic behavior
G. Confusion/restlessness
H. Emotional lability
I. Fine tremors
J. Diaphoresis
K. Hyperreflexia of deep tendon reflexes
L. Resting tachycardia/palpitations/atrial fibrillation
M. Exertional dyspnea
N. Low-grade fever
O. Increased appetite
P. Weight loss
Q. Frequent bowel movements
R. Smooth, warm, moist, velvety skin with occasional pruritus
S. Fine/thin hair
T. Exophthalmos
U. Eyelid lag
V. Infrequent blinking
W. Graves’ ophthalmopathy—noted in 20% to 40% of cases
IV. Laboratory/diagnostic findings
A. TSH assay—most sensitive test; levels are low in most cases of hyperthyroidism
B. Serum T3, T4, thyroid resin uptake, and free thyroxine index (FTI) values are elevated. Note: T4 may be normal, but T3 will be elevated.
C. Elevated erythrocyte sedimentation rate
D. Serum antinuclear antibody (ANA) levels are usually elevated without evidence of systemic lupus erythematosus or other autoimmune disease.
E. Hypercalcemia and anemia may be seen on complete blood cell count with decreased granulocytes.
F. For investigating the most common causes of hyperthyroidism, results of thyroid radioactive uptake tests may be used:
1. High iodine uptake is usually indicative of Graves’ disease.
2. Low iodine uptake is usually indicative of subacute thyroiditis.
G. MRI of the orbits is used to assess Graves’ ophthalmopathy, as indicated.
V. Management
A. Physician/endocrinologist consultation for newly diagnosed patients and those with comorbidities
B. Symptomatic relief: propranolol (Inderal), 10 mg PO (may increase dosage to 80 mg) 4 times a day
C. Antithyroid medications are used for mild cases of hyperthyroidism and in patients with small goiters who are afraid of using isotopes. However, a high rate of recurrence of the disease has been reported after 1 year.
1. Methimazole (Tapazole), 30-60 mg every day in three divided doses
2. Propylthiouracil, 300-600 mg every day in four divided doses
D. Radioactive iodine (131I)
1. Used to destroy goiters
2. Usually takes 3 to 4 months for the patient to become euthyroid
E. Thyroid surgery to remove the gland
1. Not a common modality
2. Used in the following cases:
a. Pregnant patients
b. Patients suspected of having cancer
3. Lugol’s solution, 2-3 drops PO every day for 10 days, to reduce the vascularity of the thyroid preoperatively by blocking the release of hormones from the thyroid gland
4. The patient must be euthyroid before the gland is removed.
F. Subacute thyroiditis—best treated with propranolol (symptomatically)
THYROID STORM (THYROTOXIC CRISIS)
I. Definition
A. A deadly, hypermetabolic state caused by inadequately controlled hyperthyroidism
B. This crisis manifests with exacerbated thyrotoxic symptoms.
II. Predisposing factors/incidence/general comments for patients with existing diagnosed or undiagnosed hyperthyroidism
