Stomatocytosis
A red blood cell shape disorder that can cause hemolytic anemia
Quick Facts
- Type: Red blood cell (hematologic) disorder
- Common causes: Inherited gene changes; some acquired causes
- Key feature: Mouth-shaped red blood cells
- Possible effect: Hemolytic anemia of varying severity
Overview
Stomatocytosis is a condition in which red blood cells take on an abnormal shape with a slit or mouth-like (stoma) area across the middle, instead of the normal smooth, dimpled disc. These cells are called stomatocytes. The shape change happens because the cell membrane does not control the flow of salts and water in and out of the cell normally, so the cells may swell or shrink and become less flexible.
Most forms are inherited and present from birth, although the severity ranges widely from no symptoms at all to a long-standing hemolytic anemia, in which red cells break down faster than the body can replace them. Small numbers of stomatocytes can also appear temporarily because of other conditions, such as heavy alcohol use or liver disease, without representing a true inherited disorder.
Symptoms
Many people with mild stomatocytosis have no symptoms and are only discovered when a blood test is done for another reason. When red cell breakdown is significant, symptoms reflect anemia and the by-products of hemolysis.
- Tiredness, weakness, or shortness of breath with activity
- Pale skin
- Yellowing of the skin or eyes (jaundice) from bilirubin released by broken-down cells
- An enlarged spleen, sometimes felt as fullness on the left side
- Gallstones at a younger age than usual, from ongoing hemolysis
Severity can vary even among family members carrying the same gene change.
Causes
Stomatocytosis results from problems with proteins and channels in the red blood cell membrane that regulate sodium, potassium, and water.
- Hereditary forms: Inherited changes in genes that control membrane ion channels lead to overhydrated (cells take in too much water) or dehydrated (xerocytosis) red cells. These are usually passed down in a dominant pattern.
- Acquired (secondary) stomatocytes: Conditions such as alcohol use disorder, liver disease, and certain medications can cause stomatocyte-shaped cells to appear without an inherited membrane defect.
The shape change makes some cells more fragile or more likely to be trapped and destroyed in the spleen.
Risk Factors
- A family history of stomatocytosis or unexplained hemolytic anemia
- Heavy alcohol use (a common cause of acquired stomatocytes)
- Liver disease
- Certain inherited metabolic conditions affecting the red cell membrane
Diagnosis
Diagnosis combines blood counts, examination of the cells under a microscope, and specialized tests.
- Complete blood count (CBC): Checks for anemia and the size of red cells.
- Blood smear: A trained technician looks for the characteristic mouth-shaped stomatocytes.
- Reticulocyte count and bilirubin: Show whether the marrow is making extra cells and whether hemolysis is occurring.
- Osmotic fragility and membrane studies: Specialized tests, sometimes with genetic testing, help confirm the type and distinguish it from other membrane disorders such as hereditary spherocytosis.
Treatment
Treatment depends on how much hemolysis and anemia are present. Many mild cases need no treatment beyond monitoring.
- Supportive care: Folic acid may be recommended to support ongoing red cell production.
- Blood transfusions: Used during severe anemia or specific stresses on the body.
- Treating the cause of acquired forms: Stopping alcohol or managing liver disease can reverse secondary stomatocytes.
- Spleen surgery (splenectomy): Generally avoided in the overhydrated inherited form because it can raise the risk of dangerous blood clots; decisions are individualized with a hematologist.
People with chronic hemolysis are monitored for gallstones and iron overload over time.
Prevention
Inherited stomatocytosis cannot be prevented, but complications can be reduced.
- Limit or avoid alcohol, which can worsen the picture
- Take folic acid if advised by your care team
- Keep up with regular blood tests and follow-up
- Consider genetic counseling if there is a family history and family planning questions
When to See a Doctor
See a doctor if you have ongoing tiredness, pale skin, or yellowing of the eyes or skin, or if anemia runs in your family. Seek prompt care for:
- Sudden worsening of fatigue, breathlessness, or chest pain
- Dark urine with jaundice, which can signal a rapid increase in hemolysis
- Severe pain in the upper right abdomen, which may indicate gallstones
Frequently Asked Questions
Is stomatocytosis inherited?
Most cases are inherited and passed down through families, usually in a dominant pattern. However, stomatocyte-shaped cells can also appear temporarily from causes such as heavy alcohol use or liver disease, which is not the same as the inherited disorder.
Does stomatocytosis always cause anemia?
No. Many people have a mild form with normal or near-normal red cell counts and never develop symptoms. Others have ongoing hemolysis that leads to anemia of varying severity, even within the same family.
How is stomatocytosis diagnosed?
It is usually identified on a blood smear, where the characteristic mouth-shaped cells are visible under the microscope. Blood counts, bilirubin, reticulocyte counts, and specialized membrane or genetic tests help confirm the type and rule out similar disorders.
Is the spleen removed to treat it?
Spleen removal is generally avoided in the overhydrated inherited form because it can increase the risk of serious blood clots. Treatment decisions, including whether surgery is appropriate, should be made with a hematologist.
References
- MedlinePlus, U.S. National Library of Medicine. Hemolytic anemia.
- National Heart, Lung, and Blood Institute (NHLBI). Hemolytic Anemia.
- Genetic and Rare Diseases Information Center (GARD). Hereditary stomatocytosis.
- American Society of Hematology. Red blood cell membrane disorders.