A normal platelet count range can change based on a person’s age. Possible reasons platelet counts may fluctuate include natural vascular aging, changes in bone marrow tissue, and altered blood plasma makeup.

Platelets — also known as thrombocytes — are colorless fragments of larger cells called megakaryocytes, commonly found in bone marrow.

The purpose of platelets is to create hemostasis, which is the prevention of hemorrhaging and the process of keeping blood inside the vessel walls.

Platelet count is an important diagnostic tool, measuring the number of platelets per microliter (mcL) of blood. It can help doctors identify potential health complications related to wound healing, bleeding disorders, and blood clotting.

This article discusses platelets in more detail and the expected platelet count based on a person’s age.

A note about sex and gender

Sex and gender exist on spectrums. This article will use the terms “male,” “female,” or both to refer to sex assigned at birth. Click here to learn more.

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For years, the general range for adult platelets has been 150,000–450,000 platelets/mcL of blood.

However, a 2014 review suggests platelet counts could change significantly based on a person’s age and sex.

The values took data from more than 40,000 inhabitants across seven Italian regions.

While it is unknown if these numbers are representative of all populations, the review authors indicate there have been similar platelet observations in the United States and different African populations:

Age (years)Approximate platelet count (male)Approximate platelet count (female)
under 5340,000330,000
5–9310,000slightly less than 310,000
10–14280,000slightly more than 280,000
75 and over215,000240,000

More recent data from a Swiss 2020 study on an aging population found that platelet count by age remained predominantly stable for females and saw an overall decline for males:

Age (years)Platelet count range (male)Platelet count range (female)
80 and over120,000–300,000165,000–300,000

It is not clear why platelet ranges change with age.

A 2016 reviewindicates several factors may contribute to changes in platelet count and function with age, including:

  • age-related changes in the bone marrow’s hematopoietic tissue, which is the tissue in which new blood cells develop
  • changes in blood plasma composition over time
  • vascular aging and disease processes

Platelet counts can indicate how the body will respond in situations involving blood clotting. A person can have too many or too few platelets, and each brings potential health complications.

High platelet count

The National Heart, Lung, and Blood Institute notes that higher-than-usual platelet counts may indicate thrombocythemia or thrombocytosis.

In thrombocythemia — also known as primary or essential thrombocythemia — a high platelet count is not attributed to another health condition.

Thrombocytosis — also known as reactive or secondary thrombocytosis — is diagnosed when another disease or condition is responsible for a high platelet count.

A high platelet count can create unnecessary blood clots throughout the body, particularly in the hands, brain, and feet.

It may cause bleeding conditions, such as nosebleeds, when unnecessary clots take up resources, and there are not enough free platelets remaining in the bloodstream.

A high platelet count can increase the risk of stroke and heart attack, among other conditions.

Low platelet count

When a person’s platelet count is too low — under 150,000/mcL, by standard guidelines — it may be difficult to stop even minor bleeding anywhere in the body.

This can create symptoms such as:

  • prolonged bleeding, even from small injuries
  • bruising
  • red or purple spots on the skin from leaking blood vessels
  • heavy menstrual bleeding
  • blood in the urine or stool
  • bleeding from the nose or gums

A low platelet count is known as thrombocytopenia, and it can occur as a result of:

  • environmental exposures
  • medication
  • lifestyle habits
  • another medical condition
  • genetics

When a person’s platelets are below typical levels for an extended period, medications can help increase platelet count or stop the body from destroying its own platelets in the case of autoimmune conditions.

Surgery or a blood or platelet transfusion may be necessary in extreme cases.

Platelets are essential components of blood clotting and wound healing. When the body experiences bleeding, platelets adhere together to create clots and stop blood loss.

The standard counts have remained at the broad range of 150,000–450,000 platelets/mcL of blood. However, evidence suggests the typical range for platelets may vary based on age and gender.

The reasons behind age-related platelet fluctuations are unclear. However, bone marrow changes, vascular aging, and changes in blood composition over time may all affect how many platelets are in the bloodstream.