Black urine

Introduction Black urine is relatively rare, often occurring in patients with acute intravascular hemolysis, such as falciparum malaria, medically known as black urine fever, is one of the most serious complications of falciparum malaria. The patient's plasma contains a large amount of free oxygen, hemoglobin and oxyhemoglobin, which are dark red or black in urine. A small number of patients who take levodopa, cresol, benzoquinone, etc., will also cause black urine, which will disappear after stopping the drug. According to foreign reports, patients with paroxysmal myoglobinuria will also explode brown-black urine after exercise, accompanied by muscle weakness, which can gradually develop into dysentery. In addition, black urine can also be seen in phenol poisoning, black tumor, and urinary acidosis.

Cause

The patient lacks urinary acid oxidase and thus cannot decompose urinary acid. Genes control the formation of enzymes, which in turn affect metabolic processes.

an examination

1 Add an appropriate amount of alkaline reagent to the urine to accelerate the appearance of urinary blackening.

2 After the alkali is basified, the Ban's reagent is brown, and the general reducing substance is orange-yellow.

3 adding chlorinated high-iron reagent can make the urine purple-black.

4 Take 0.5ml of urine and add 5ml of saturated silver nitrate aqueous solution to immediately show black, but vitamin C can cause false positive results. The patient's fresh urine has no abnormal appearance. After being placed and exposed to the air, the uric acid can be oxidized to melanin to make the urine black.

Differential diagnosis

The patient's fresh urine has no abnormal appearance. After being placed and exposed to the air, the uric acid can be oxidized to melanin to make the urine black. The patient is often asymptomatic during childhood. Occasionally, the baby's diaper is found to be black-stained, and some patients are treated to become black after finding the urine. Some patients have acidic or more reducing substances. It does not change color when placed for several hours. Adult patients have brownish yellow disease due to long-term melanin deposition in the tissue, which mainly causes spinal and joint lesions. The renal threshold of uric acid is very low, a large amount of uric acid is excreted from the urine, up to several grams per day, and the blood concentration is often not significantly increased. Bilirubin, porphyrin, myoglobin and hemoglobin can make the urine darker and should be distinguished.

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