Scanning electron microscopy (SEM) of echinocytes

Echinocyte (from the Greek word ''echinos'', meaning 'hedgehog' or 'sea urchin'), in human biology and medicine, refers to a form of

red blood cell Red blood cells (RBCs), also referred to as red cells, red blood corpuscles (in humans or other animals not having nucleus in red blood cells), haematids, erythroid cells or erythrocytes (from Greek ''erythros'' for "red" and ''kytos'' for "holl ...

that has an abnormal

cell membrane The cell membrane (also known as the plasma membrane (PM) or cytoplasmic membrane, and historically referred to as the plasmalemma) is a biological membrane that separates and protects the interior of all cells from the outside environment ( ...

characterized by many small, evenly spaced thorny projections.Mentzer WC. Spiculated cells (echinocytes and acanthocytes) and target cells. UpToDate (release: 20.12- C21.4

/ref> A more common term for these cells is burr cells.

Physiology

Echinocytes are frequently confused with

acanthocyte Acanthocyte (from the Greek word ἄκανθα ''acantha'', meaning 'thorn'), in biology and medicine, refers to an abnormal form of red blood cell that has a spiked cell membrane, due to thorny projections. A similar term is spur cells. Often ...

s, but the mechanism of cell membrane alteration is different. Echinocytosis is a reversible condition of red blood cells that is often merely an artifact produced by

EDTA Ethylenediaminetetraacetic acid (EDTA) is an aminopolycarboxylic acid with the formula H2N(CH2CO2H)2sub>2. This white, water-soluble solid is widely used to bind to iron (Fe2+/Fe3+) and calcium ions (Ca2+), forming water-soluble complexes eve ...

, which is used as an

anticoagulant Anticoagulants, commonly known as blood thinners, are chemical substances that prevent or reduce coagulation of blood, prolonging the clotting time. Some of them occur naturally in blood-eating animals such as leeches and mosquitoes, where the ...

in sampled blood. Echinocytes can be distinguished from acanthocytes by the shape of the projections, which are smaller and more numerous than in acanthocytes and are evenly spaced. Echinocytes also exhibit central pallor, or lightening of color in the center of the cell under

Wright stain Wright's stain is a hematologic stain that facilitates the differentiation of blood cell types. It is classically a mixture of eosin (red) and methylene blue dyes. It is used primarily to stain peripheral blood smears, urine samples, and bone marr ...

ing.

Causes

In addition to appearing as an artifact of staining or drying, echinocytes are associated with: * Uremia and

chronic kidney disease Chronic kidney disease (CKD) is a type of kidney disease in which a gradual loss of kidney function occurs over a period of months to years. Initially generally no symptoms are seen, but later symptoms may include leg swelling, feeling tired, vo ...

pyruvate kinase deficiency Pyruvate kinase deficiency is an inherited metabolic disorder of the enzyme pyruvate kinase which affects the survival of red blood cells. Both autosomal dominant and recessive inheritance have been observed with the disorder; classically, and ...

hypophosphatemia Hypophosphatemia is an electrolyte disorder in which there is a low level of phosphate in the blood. Symptoms may include weakness, trouble breathing, and loss of appetite. Complications may include seizures, coma, rhabdomyolysis, or softening ...

hyperlipidemia Hyperlipidemia is abnormally elevated levels of any or all lipids (fats, cholesterol, or triglycerides) or lipoproteins in the blood. citing: and The term ''hyperlipidemia'' refers to the laboratory finding itself and is also used as an umbre ...

* Phosphoglycerate kinase deficiency * Disseminated malignancy * Myeloproliferative disorders *

Vitamin E deficiency Vitamin E deficiency in humans is a very rare condition, occurring as a consequence of abnormalities in dietary fat absorption or metabolism rather than from a diet low in vitamin E. Collectively the EARs, RDAs, AIs and ULs for vitamin E and other ...

* Early posttransfusion of RBC Echinocytes, like acanthocytes, may be found in hyperlipidemia caused by liver dysfunction, but the lipids themselves do not integrate into the membrane. Instead, it is speculated that cell surface receptors on the red blood cells bind with

HDL cholesterol High-density lipoprotein (HDL) is one of the five major groups of lipoproteins. Lipoproteins are complex particles composed of multiple proteins which transport all fat molecules (lipids) around the body within the water outside cells. They are t ...

, which induces the shape change. These cells were also shown to develop in vivo during

hemodialysis Hemodialysis, also spelled haemodialysis, or simply dialysis, is a process of purifying the blood of a person whose kidneys are not working normally. This type of dialysis achieves the extracorporeal removal of waste products such as creatinin ...

, and disappear at the end of the procedure. The level of echinocytosis appeared to be related to the increase in blood viscosity that occurs during hemodialysis. The formation of echinocytes can be determined by electric field pulses. Alternating electric current produces modifications in the membranes of red blood cells, attributed to a higher permeability to water and a decreased tonicity, leading to the transformation into echinocytes.

References

{{Abnormal clinical and laboratory findings Abnormal clinical and laboratory findings for RBCs Histopathology

Physiology

Causes

See also

References