Platelet Count
The number of platelets, the small blood cells that help your blood clot, in a sample of your blood.
AI-verified against cited sources. Awaiting expert reviewAlso called PLT, PltLOINC 777-3
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What it is
Platelets (thrombocytes) are tiny cell fragments made in your bone marrow. When a blood vessel is hurt, they stick together to plug the leak and help a clot form. The platelet count is how many are in your blood. It is part of a complete blood count (CBC). Platelets live only about a week, so the number reflects what your bone marrow has been doing recently.
Why it matters
Too few platelets can make you bruise or bleed more easily. Too many can, in some situations, raise the chance of unwanted clots. Mildly low or high counts are common and are often temporary, for example after a virus, during pregnancy or during an inflammatory illness. Clinicians look at how far the count is from the usual range and how it changes over time.
If it’s low
A low count (thrombocytopenia) can cause easy bruising, nosebleeds or bleeding that lasts longer after a cut. Mildly low counts are common and often have harmless explanations, such as a recent viral illness, pregnancy, or platelets clumping in the tube so the lab undercounts them. Counts that fall well below the usual range are linked to a higher chance of bleeding, so clinicians look for the cause.
Common causes
- A recent viral infection
- Pregnancy: a mild drop called gestational thrombocytopenia is common
- Platelets clumping in the blood tube, which makes the count read falsely low
- Some medicines, including some antibiotics and blood thinners
- Heavy alcohol use or liver disease
- Low vitamin B12
- Autoimmune conditions, including immune thrombocytopenia (ITP) and lupus
- Bone marrow problems or blood cancers such as leukemia
- An enlarged spleen
What can help
- Ask whether the count should be repeated, and whether a blood smear or a different tube is needed to rule out clumping
- Tell your clinician about every medicine and supplement you take, including blood thinners and anti-inflammatory pain relievers
- Ask whether any activities should be limited while your count is low
If it’s high
A high count (thrombocytosis) is most often a reaction to something else, such as an infection, inflammation, low iron, recent surgery or blood loss. It usually settles when that gets better. Less often, the bone marrow makes too many platelets on its own. A count that stays high needs a clinician's review to tell these apart.
Common causes
- Infection or other inflammation, such as inflammatory bowel disease or rheumatoid arthritis
- Iron deficiency or other anemia
- Recent surgery, injury or significant blood loss
- Recovery after a period of low platelets
- Having had the spleen removed
- Some cancers
- Less often, a bone marrow condition that makes extra platelets
What can help
- Ask your clinician whether to repeat the count and check iron and signs of inflammation
- Tell your clinician about symptoms such as headaches, numbness in your hands or feet, or pain and swelling in a leg
- Review your medicines and supplements with your clinician
Usual ranges
What labs print as the reference range, by who was tested. Ranges differ a little between labs, so the range on your own report is the one your result is judged against.
For adults: 150–450 ×10³/µL. Source: Labcorp, American Board of Pathology, Quest Diagnostics, Oregon Health & Science University, Te Whatu Ora Health New Zealand, Waikato, University of Iowa Hospitals & Clinics, PLoS ONE, Journal of Clinical Pathology. Labs treat below 20 ×10³/µL as urgent.
- Adults (this one applies)150–450 ×10³/µL
Sources: Labcorp, American Board of Pathology, Quest Diagnostics, Oregon Health & Science University, Te Whatu Ora Health New Zealand, Waikato, University of Iowa Hospitals & Clinics, PLoS ONE, Journal of Clinical Pathology
See Platelets by age and sex, with the U.S. survey numbers where they exist.
If this applies to you
Platelets means a little more for some people. Open the one that fits you.
Hemochromatosis or iron overload
ACG reads the platelet count together with ferritin and liver enzymes to judge the chance of liver scarring when hemochromatosis is first found. A low count is part of the combination it links to cirrhosis.
Fatty liver or liver condition
Platelets are part of FIB-4. BSG notes that a low platelet count is the most common blood-count change in long-term liver disease and can be a sign of more advanced disease.
Pregnant or postpartum
Platelet counts often drift lower in pregnancy, most often in the third trimester. This mild dip, called gestational thrombocytopenia, is common, is not linked to harm for parent or baby, and usually recovers after birth. Clinicians watch how low it goes, since less common causes such as preeclampsia can also lower platelets.
Taking methotrexate
Platelets help blood clot, and methotrexate can lower them along with other blood cells. They are part of the full blood count the BSR suggests at every check.
How common is your level?
NHANES describes the US civilian, non-institutionalized population, not a 'healthy' reference group. People with disease, on medication, fasting or not (except fasting-subsample markers), smokers and so on are all included. A percentile says where a value sits among Americans of that sex and age, not whether it is normal.
Use the left and right arrow keys to read each age. Shift moves five years.
Reference data derived from CDC/NCHS National Health and Nutrition Examination Survey (NHANES), cycles 2015-2016, 2017-March 2020 (pre-pandemic), August 2021-August 2023. Analysis by bloodtesttracker.com; not endorsed by CDC, NCHS or HHS.
Explore Platelets by age and sex: every percentile as a table, with a download.
What can affect your result
- Sex: women tend to have somewhat higher counts than men
- Age: counts are higher in children and tend to be lower in older adults
- Ancestry: people of African ancestry often have slightly lower counts
- Pregnancy: counts often drift lower, especially in the third trimester
- Iron levels: low iron can raise the count
- Infection and inflammation, which can raise it
- Platelet clumping in the tube, which can lower the reported count
- Platelets can clump in the usual purple-top (EDTA) tube in some people, which makes the machine undercount them (pseudothrombocytopenia). Labs often confirm with a blood smear or recount from a different tube.
- A difficult (traumatic) blood draw, or a sample kept in the refrigerator, can trap platelets in small clots and lower the count.
- Fragments of red cells, cell debris and very large platelets can be miscounted by automated analyzers, so a count can read falsely high or low.
- Labs reject a clotted or grossly hemolyzed sample.
Platelets live about a week, so the count can shift within days to a couple of weeks.
When to talk to a clinician
Labs phone a clinician right away when the count is 20 ×10³/µL or lower, or 1,000 ×10³/µL or higher (ARUP's urgent-call limits; other labs use slightly different limits). If you have signs of bleeding, such as easy bruising, nosebleeds, bleeding gums, heavy periods, tiny red or purple spots on the skin, or blood in your urine or stool, contact a clinician soon, whatever your count is. Call 911 or your local emergency number for bleeding that won't stop, a sudden severe headache, chest pain, trouble breathing or confusion.
Questions you could ask
- How does my platelet count compare with my earlier results?
- Could low iron, inflammation or a recent illness explain a high count?
- Should we repeat the count in a few weeks?
- Could this be platelet clumping, and should the lab recheck it?
- Do any of my medicines or supplements affect platelets?
- Should we repeat the count, and how soon?
Questions people ask
My platelets are slightly low. Is that serious?
A mildly low count is common and often has a harmless cause, such as a recent virus, pregnancy, or platelets clumping in the tube so the machine undercounts them. Your clinician may repeat the test or ask the lab to check a blood smear. Counts that are well below the usual range get a closer look.
What is platelet clumping (pseudothrombocytopenia)?
In some people, the chemical in the standard purple-top tube (EDTA) makes platelets stick together. The machine then counts fewer than are really there. A lab can often spot this and recount from a different type of tube. It is a lab artifact, not a sign that your platelets don't work.
Is a high platelet count a problem?
Most high counts are temporary reactions to infection, inflammation, low iron or recent surgery, and they return to the usual range once that settles. A count that stays high, or comes with symptoms, is worth a clinician's review.
My report says 2.5 lakh. What is that in ×10³/µL?
Labs in India often print platelets as lakhs per cubic millimeter. One lakh is 100,000, so 2.5 lakh is 250,000 per µL, which is 250 ×10³/µL. Multiply lakhs by 100 to get ×10³/µL.
Why do labs list different normal ranges for platelets?
Labs use different instruments and reference groups. Many list 150–450 ×10³/µL, Quest lists 140–400 for adults, and others use 150–400. Large studies also show counts differ by sex, age and ancestry. Use the range printed on your own report.
Show the science and sources
Units
- 1 ×10³/µL = 1 ×10³/µL
- 1 ×10³/µL = 1 ×10⁹/L
- 1 ×10³/µL = 1000 cells/µL
- 1 ×10³/µL = 0.01 lakh/mm³
Open the Platelets unit converter
Is a change real?
Platelets naturally varies about 7.1% from test to test in the same healthy person. Between two results from the same lab, a change of roughly 22% or more is unlikely to be day-to-day noise or lab variation (95% reference change value). Source: Systematic review and meta-analysis of within-subject and between-subject biological variation estimates of 20 haematological parameters (Coskun A et al., EFLM WG-BV).
For clinicians and researchers
Platelets are anucleate fragments of megakaryocytes with a life span of roughly 7–10 days. Thrombopoietin from the liver drives production, and part of the platelet pool is held in the spleen. Automated analyzers count them by impedance or optical or fluorescence methods. EDTA-dependent clumping (pseudothrombocytopenia) is the classic cause of a falsely low count; it is confirmed on a smear or by recounting in a citrate or heparin tube. Red cell fragments, debris and microcytes can be counted as platelets, and giant platelets can be counted as red cells. Adult reference limits in the sources used run 140–150 (lower) and 400–450 ×10³/µL (upper). Women have higher counts than men after puberty, counts fall with age, and counts are lower on average in people of African ancestry. Population data (Biino 2013, 40,987 people in Italy) support sex- and age-specific limits. Reactive thrombocytosis is much more common than clonal thrombocytosis; the 2010 British Committee for Standards in Haematology guideline covers the work-up. Gestational thrombocytopenia accounts for about 75% of low counts in pregnancy and is usually mild (about 100–150 ×10³/µL).
LOINC 777-3 (primary), 26515-7, 778-1. Specimen: whole-blood.
Sources
- CBC, Platelet, No Differential (test 028142), sample report, Labcorp (2020)
- Hematopathology reference ranges, American Board of Pathology
- Platelet Count, EDTA, test 723, Quest Diagnostics
- Heme Reference Ranges (updated 6/5/18), Oregon Health & Science University (2018)
- CBC reference intervals (HEM-2597.01), Te Whatu Ora Health New Zealand, Waikato (2024)
- CBC (Complete Blood Count), Pathology Handbook, University of Iowa Hospitals & Clinics
- Age- and Sex-Related Variations in Platelet Count in Italy: A Proposal of Reference Ranges Based on 40987 Subjects' Data, PLoS ONE (2013)
- Ethnic and sex differences in the total and differential white cell count and platelet count, Journal of Clinical Pathology (1996)
- Critical Values List (CORP-APPEND-0104A, Rev. 46), ARUP Laboratories (2026)
- Appendix 1: Critical Value List, The University of Chicago Medical Center Laboratories
- Diagnostic Laboratories: Critical Values, Houston Methodist
AI-verified against cited sources. Awaiting expert review. Last reviewed 2026-10-03. How we build and check these pages.