Palpitation case 1

A 26-year-old woman presents to her physician's office with multiple complaints for the last few months. She has been feeling very anxious and will sometimes feel that her heart is racing. She also has been feeling really hot despite the fact that it is the middle of winter. She has been feeling very hungry, and has not been able to sleep for more than 3 hours a day. Her last menstrual period was "months ago" and she has been sexually active without using any contraception. Her medical history is significant for an episode of untreated depression 2 years ago. She denies taking any medications. On examination, she appears agitated and is rocking her legs throughout the entire interview. She is talking very rapidly, and interrupts the interviewer frequently. Her blood pressure is 146/80 mm Hg, and her pulse is 103/min. Her examination is significant for some staring and a slightly enlarged and firm thyroid. Routine laboratory studies, a urinary pregnancy test, and an ECG are obtained.

Q1

Which of the following is the most likely preliminary diagnosis?
/ A. Anxiety attacks
/ B. Goiter
/ C. Hyperthyroidism
/ D. Manic episode of bipolar illness
/ E. Supraventricular tachycardia

Q2

Which of the following is the most likely diagnosis?
/ A. Chronic lymphocytic thyroiditis
/ B. Graves disease
/ C. Hashimoto disease
/ D. Subacute thyroiditis
/ E. Toxic multinodular goiter

Q3

Which of the following tests is the best to establish the diagnosis in this patient?
/ A. Radioactive iodine uptake and scan
/ B. Serum antithyroglobulin antibodies
/ C. Serum anti-thyroid peroxidase antibodies
/ D. Serum thyroid stimulating hormone (TSH)
/ E. UItrasound of the neck

Q4

How could a physician differentiate between a patient with this patient's disease and a patient who surreptitiously had ingested thyroid hormones to lose weight?
/ A. Needle aspiration or biopsy of the thyroid
/ B. Radioactive iodine uptake
/ C. Serum free T4 Ievels
/ D. Serum TSH Ievels
/ E. Thyroid scan

Q5

Which of the following will provide the most rapid relief of the patient's cardiac signs and symptoms?
/ A. L-thyroxine
/ B. Methimazole
/ C. Nadolol
/ D. Potassium iodide
/ E. Propylthiouracil
____________________________________________________________________

Palpitation case 1 answers:

A1
The correct answer is C. Hyperthyroidism is suggested by the clinical presentation. Symptoms of hyperthyroidism include anxiety, tremors, insomnia, heat intolerance, and amenorrhea. Patients may or may not have goiters. Suppression of TSH levels and elevation of free thyroxine levels would confirm the likely diagnosis.
Patients with anxiety attacks (choice A) can have similar symptoms as patients with hyperthyroidism, so that ruling out the latter is important in the diagnosis of anxiety disorder. However, the "staring" and thyroid enlargement suggest hyperthyroidism.
Patients with goiters (choice B) can be hyperthyroid, but can be euthyroid, without any symptoms, as well.
Given the patient's history of depression, it is possible that the patient is undergoing the manic phase of bipolar disorder (choice D). Again, hyperthyroidism should be ruled out first prior to further psychiatric evaluation.
Supraventricular tachycardia (choice E) can occur in young women, and can be associated with hyperthyroidism. However, the patient with isolated supraventricular tachycardia without hyperthyroidism would not have the associated positive review of systems (e.g., insomnia, polyphagia, weight loss).
Laboratory studies are significant for a TSH Ievel of 0.02 U/mL and serum
free T4 of 2.5 ng/dL (normaI 0.8-1.45 ng/dL).

A2
The correct answer is B. Graves disease is the most common cause of hyperthyroidism, and occurs mostly in young women. It is an autoimmune disease in which immune cells produce a thyroid-stimulating immunoglobulin (IgG TSI) that binds to and stimulates the thyroid TSH receptor. Graves disease is defined by a triad of signs: hyperthyroidism with a diffuse symmetric goiter, ophthalmopathy (the stare), and dermopathy (pretibial myxedema). Graves disease is associated with an elevated radioiodine uptake scan (RAIU), and elevated thyroglobulin and anti-thyroid peroxidase antibodies.
Chronic lymphocytic thyroiditis/chronic thyroiditis (choice A) is a painless inflammation of the thyroid associated with a transient thyrotoxicosis progressing to a hypothyroid state. It can be differentiated from Graves disease by having a low RAIU.
Hashimoto disease (choice C) is the most common cause of hypothyroidism, and often presents with a multinodular, firm, and asymmetric goiter. Like Graves disease, it is autoimmune in nature and tends to occur in women of the same family. There are associated high titers of antithyroid peroxidase (anti-TPO) antibodies and antithyroglobulin antibodies.
Patients with subacute thyroiditis (choice D) have a characteristically very painful, nodular, and asymmetrically enlarged thyroid gland. This disorder tends to occur after a viral upper respiratory infection. Labs show a low RAIU, but a high erythrocyte sedimentation rate. Like chronic thyroiditis, patients can first present in the thyrotoxic stage prior to becoming hypothyroid, and then euthyroid.
Patients with toxic multinodular goiter (choice E) are also hyperthyroid, but with an enlarged and nodular thyroid. As in Graves disease, the RAIU is increased.


A3
The correct answer is A. Radioactive iodine uptake scan (RAIU) is the main tool to differentiate between the different causes of hyperthyroidism. It is elevated in Graves disease and toxic nodular goiter. It is not used if the patient is hypothyroid.
Antithyroglobulin levels (choice B) are more commonly elevated in Graves disease but they can present in Hashimoto disease as well. They are also used as a marker for thyroid cancer and used as a surveillance agent in treated patients
Elevated anti-thyroid peroxidase antibodies (choice C) are more commonly seen in patients with Hashimoto disease but they can be present in Graves disease too.
Serum TSH levels (choice D) would not distinguish between Graves disease and toxic nodular goiter.
An ultrasound (choice E) is only used to determine if a nodule within a goiter is solid or cystic.


A4
The correct answer is B. Both these patients will have elevated free T4 levels (choice C) and suppressed TSH levels (choice D) regardless of the cause of hyperthyroidism. However, patients taking thyroid supplements will have a low RAIU (choice B) versus a high RAIU in patients with Graves disease.
A thyroid scan (choice E) is a nuclear study that indicates activity in the thyroid nodules; a hot nodule has more active thyroid function than a cold nodule. It is only used on nodular disease


A5
The correct answer is C. Nadolol is a non-cardioselective beta-receptor blocker used to treat the signs and symptoms of hyperthyroidism, such as palpitations, anxiety, tremor, and heat intolerance. Beta-blockers may also partially inhibit the peripheral conversion of T4 to T3. However, they do not reduce thyroid-stimulating antibodies or prevent thyroid storm. These agents will produce a rapid reduction of the patients cardiac signs and symptoms. It is important to note that although methimazole (choice B), potassium iodide (choice D), and propylthiouracil (choice E) are indicated for the treatment of Graves disease, nadolol will produce the fastest reduction of cardiac signs and symptoms.
L-thyroxine (choice A) is indicated for treatment of hypothyroidism. The use of this agent in this patient would worsen the patient's condition.
Methimazole (choice B) and propylthiouracil (PTU) (choice E) act by inhibiting the synthesis of the thyroid hormones. PTU and methimazole do NOT inactivate existing T4 and T3 and PTU is able to inhibit the peripheral conversion of T4 to T3. The full therapeutic effect usually occurs 4 - 8 weeks after the initiation of therapy; the symptoms should be diminished and the thyroid hormones should be back to within normal limits. These agents are indicated for long-term hyperthyroid therapy, which may lead to disease remission, and for short-term treatment before thyroidectomy or radioactive iodine therapy. PTU may also be useful for decreasing mortality due to alcoholic liver disease by reducing the hepatic hypermetabolic state induced by alcohol (unlabeled indication).
Potassium iodide (choice D) was the first therapeutic option for treatment of Graves disease. It inhibits the release of T4 and T3, inhibits the biosynthesis of T4 and T3, and decreases the size and vascularity of the thyroid gland. The therapeutic effects begin to be seen in approximately 2 - 7 days. If used on a chronic basis, the therapeutic effects can be observed for up to 6 weeks. T4 and T3 concentrations may return to normal for a few weeks.