Sysmex 2024 Fall Newsletter - Flipbook - Page 14
What is Hemosiderin?
Hemosiderin is a granular form of hemoglobin that can be seen in the urine
of patients with intravascular hemolysis. In conditions that cause hemolysis,
such as paroxysmal nocturnal hemoglobinuria (PNH), hemoglobin is released
from disrupted RBCs in the peripheral blood, then binds to haptoglobin for
transport to the liver, where it will be cleared from the body. If the amount of
extracellular hemoglobin exceeds the capacity of haptoglobin, the excess is
released into the urine where it is partially reabsorbed in the renal tubules.
In these tubular cells, the hemoglobin is converted to ferritin and then to
hemosiderin, which is eventually released into the urine as the renal tubular
cells degenerate.
Unstained hemosiderin is seen in the urine as yellowish-brown granules and
may appear in macrophages, hemosiderin casts or be free-昀氀oating. Testing for
urine hemosiderin usually involves concentrating the sample and staining the
sediment with a Prussian blue solution, in which the hemosiderin will
appear blue.
Urine hemosiderin testing may be performed to monitor patients with severe
acute hemolytic anemia, PNH, hemochromatosis or in the case of an
incompatible blood transfusion.
Morphology/Features:
•
Small yellowish-red granules in unstained urine
•
May be intracellular, free-昀氀oating or in hemosiderin casts
•
Can resemble amorphous material
•
Con昀椀rm with Prussian blue reaction
Resources
Atlas of Urinary Sediment, Sysmex Corporation, Kobe, Japan.
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