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Related Experiment Videos

Black urine

P Altmann, M A Mansell

    Postgraduate Medical Journal
    |December 1, 1980
    PubMed
    Summary
    This summary is machine-generated.

    Alpha-methyldopa treatment can cause urine to darken due to melanin formation. This effect is more noticeable in alkaline urine after correcting hyponatraemic alkalosis.

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    Area of Science:

    • Pharmacology
    • Clinical Chemistry

    Background:

    • Alpha-methyldopa is a medication commonly used to treat hypertension.
    • Melanin is a pigment responsible for various colors in the body.
    • Urine pH can significantly influence chemical reactions and metabolite stability.

    Observation:

    • A patient treated with alpha-methyldopa exhibited spontaneous blackening of their urine.
    • The urine discoloration was attributed to melanin formation.
    • This phenomenon became apparent only after the patient's severe postoperative hyponatraemic alkalosis was corrected.

    Findings:

    • Melanin formation in urine is pH-dependent, occurring more readily in alkaline conditions.
    • Acidic urine significantly slows down the rate of melanin precipitation.
    • The observed urine blackening was a direct consequence of altered urinary pH following medical intervention.

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    Implications:

    • Clinicians should be aware of potential urine color changes with alpha-methyldopa, especially in patients with fluctuating acid-base balance.
    • Monitoring urinary pH may be important in patients experiencing unexpected urine discoloration during alpha-methyldopa therapy.
    • This case highlights the interplay between drug metabolism, urinary pH, and observable clinical signs.