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  1. #1
    BioPatel is offline Member
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    Plasma catecholamines are elevated

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    A 35-year-old woman complains to her physician that she has headaches accompanied by heart palpitations. In the physician's office the patient's blood pressure is 120/70 mmHg. However, later in the day, the patient returns to the office when she is symptomatic and she has a pulse rate of 95/min with a blood pressure of 190/140 mmHg. Plasma catecholamines are elevated and a CT scan later demonstrates an adrenal mass. The catecholamines demonstrated in the plasma are derived from which of the following amino acids?

    A. Arginine
    B. Glutamate
    C. Glycine
    D. Tryptophan
    E. Tyrosine

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    Asclepius1 is offline Ultimate Member 537 points
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    E.

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    Asclepius1's Avatar
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    Re: Plasma catecholamines are elevated

    Quote Originally Posted by BioPatel
    A 35-year-old woman complains to her physician that she has headaches accompanied by heart palpitations. In the physician's office the patient's blood pressure is 120/70 mmHg. However, later in the day, the patient returns to the office when she is symptomatic and she has a pulse rate of 95/min with a blood pressure of 190/140 mmHg. Plasma catecholamines are elevated and a CT scan later demonstrates an adrenal mass. The catecholamines demonstrated in the plasma are derived from which of the following amino acids?

    A. Arginine
    B. Glutamate
    C. Glycine
    D. Tryptophan
    E. Tyrosine

    yes the answer must be E since the phenylalanine and tyrosine are precursor of cathecholamines


  4. #4
    BioPatel is offline Member
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    The correct answer is E. This question takes several logic steps to answer. The first thing to figure out is that the patient has an adrenal pheochromocytoma that is causing episodic hypertension (leading to headache) and arrhythmia (leading to palpitations). The next item to know is that the plasma catecholamines that are measured include epinephrine, norepinephrine, and dopamine. The last thing to know is that all three of these are derived from tyrosine (which is, in turn, derived from phenylalanine).
    Arginine (choice A) is the amino acid precursor of the biological messenger nitric oxide (N0).

    Glutamate (choice B) is the amino acid precursor of gamma-amino butyric acid (GABA).

    Glycine (choice C) is a neurotransmitter, not a precursor.

    Tryptophan (choice D) is the amino acid precursor of 5-hydroxytryptophan, serotonin, and melatonin.

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