Why is urine soy sauce colored?

Urine is waste product excreted from the body and is usually colorless or yellow. The color of urine is closely related to our health. If the color of urine is abnormal, it means that there may be problems with our health. In daily life, many people find that their urine is soy sauce color and are very concerned about the reasons. So, what's the deal with the soy sauce color of urine? Let’s take a look at the reasons below.

It is common in favism, paroxysmal nocturnal hemoglobinuria and blood transfusion reactions due to blood type incompatibility.

This is because when red blood cells are destroyed in large numbers in the blood vessels (i.e. intravascular hemolysis), the hemoglobin in the red blood cells will be released, causing a large amount of free hemoglobin to appear in the plasma and be excreted from the kidneys. This is called hemoglobinuria, and its color is red wine or soy sauce color.

Clinical manifestations

Intravascular hemolysis is often severe and often presents with systemic symptoms such as chills, fever, back pain, jaundice, and hemoglobinuria. It may lead to shock, exhaustion, and death within a short period of time. Chronic intravascular hemolysis may also cause hemosiderinuria.

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Free hemoglobin

There is only a trace amount of free hemoglobin in normal plasma, about 10~40 mg/L. It may increase during intravascular hemolysis.

Serum haptoglobin

The normal range is 0.5~1.5g/L. Serum haptoglobin decreases during intravascular hemolysis. It takes about 3 to 4 days for the plasma binding globin to recover after the acute bleeding stops.

Hemoglobinuria

In the case of hemoglobinuria, urine routine test shows positive occult blood, positive urine protein, and negative red blood cells.

Hemosiderinuria

It refers to the discovery of hemosiderin in desquamated epithelial cells during routine urine microscopy. Mainly seen in chronic intravascular hemolysis.

Reticulocytes

During intravascular hemolysis, the percentage of reticulocytes increases and can reach 5%-20%.

Bone marrow smear

The bone marrow erythroid cells proliferate actively, mainly consisting of intermediate and late immature erythrocytes, and the granulocyte-erythrocyte ratio may be inverted.

Peripheral blood smear

Nucleated red blood cells can be seen in the peripheral blood smear. Some red blood cells contain nuclear fragments, such as Howell-Jolly bodies and Cabot rings.

Common causes

Blood transfusion due to incompatible blood type

Infusion of hypotonic solution

Paroxysmal nocturnal hemoglobinuria (PNH)

G-6-PD Deficiency

Cold antibody autoimmune hemolytic anemia