A 54-year-old female takes levothyroxine (Synthroid), 0.125 mg/day, for central hypothyroidism secondary to a pituitary adenoma. The nurse practitioner in your office orders a TSH level, which is found to be 0.1 mIU/mL (N 0.5-5.0).
Which one of the following would you recommend?
Correct Answer C:
Although uncommon, pituitary disease can cause secondary hypothyroidism. The characteristic laboratory findings are a low serum free T4 and a low TSH. A free T4 level is needed to evaluate the proper dosage of replacement therapy in secondary hypothyroidism. The TSH level is not useful for determining the adequacy of thyroid replacement in this case, and the low level would prevent the physician from determining whether the dosage of levothyroxine is appropriate. In the initial evaluation of secondary hypothyroidism, a TRH stimulation test would be useful if TSH failed to rise in response to stimulation. It is not necessary in this case, since the diagnosis has already been made.
A 67-year-old female presents with progressive weakness, dry skin, lethargy, slow speech, and eyelid edema. Of the following medications currently taken by this patient, which one is most likely to be causing her symptoms?
Correct Answer B:
This patient has classic signs of hypothyroidism. Of the drugs listed, only lithium is associated with the development of hypothyroidism. In patients taking lithium, it is recommended that in addition to regular serum lithium levels, thyroid function tests including total free T , and TSH be obtained yearly.
An asymptomatic 55-year-old male visits a health fair, where he has a panel of blood tests done. He brings the results to you because he is concerned about the TSH level of 12.0 mU/L. His free T4 level is normal.
Which one of the following is most likely to be associated with this finding?
Correct Answer D:
With subclinical thyroid dysfunction, TSH is either below or above the normal range, free T4 or T3 levels are normal, and the patient has no symptoms of thyroid disease. Subclinical hypothyroidism (TSH > 10 mU/L) is likely to progress to overt hypothyroidism. Patients with a serum thyroid-stimulating hormone level greater than 10 mU/L have a higher incidence of elevated serum low-density Lipoprotein cholesterol concentrations. Subclinical hyperthyroidism (TSH < 0.1 mU/L) is associated with the development of atrial fibrillation, decreased bone density, and cardiac dysfunction. Neither type of subclinical thyroid dysfunction is associated with diabetes mellitus. There is insufficient evidence of benefit to warrant early treatment of either condition.
Which of the following medications may cause amnesia as a side effect?
Triazolam is a benzodiazepine medications used for sleep disorders. It can be addictive if used improperly. This medication can cause sedation and, because of this, use of triazolam by seniors can contribute to falls and accidents and cause confusion and amnesia.
A 36-year-old white female presents to the emergency department with palpitations. Her pulse rate is 180 beats/min. An EKG reveals a regular tachycardia with a narrow complex QRS and no apparent P waves. The patient fails to respond to carotid massage or to two doses of intravenous adenosine (Adenocard), 6 mg and 12 mg.
The most appropriate next step would be to administer intravenous:
Correct Answer E:
If supraventricular tachycardia is refractory to adenosine or rapidly recurs, the tachycardia can usually be terminated by the administration of intravenous verapamil or a beta-blocker. Verapamil has a longer half-life than adenosine and may help maintain sinus rhythm following the termination of SVT. It is also advantageous for controlling the ventricular rate in patients with atrial tachyarrhythmia. If that fails, intravenous propafenone or flecainide may be necessary. It is also important to look for and treat possible contributing causes such as hypovolemia, hypoxia, or electrolyte disturbances. Electrical cardioversion may be necessary if these measures fail to terminate the tachyarrhythmia. Consider radiofrequency ablation for any patient with symptomatic paroxysmal supraventricular tachycardia in whom long-term medical treatment is not effectively tolerated or desired.
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