- 01A low number alone vs a low number in a bad pattern
A platelet count of 100 to 149 that is stable, in someone who feels well and whose hemoglobin and white cells are normal, is usually benign: the 10-year chance of developing ITP is about 7 in 100 3. The same count is urgent when it has halved within days, when other cell lines are also low, or when the smear shows fragmented red cells.
A platelet count below 150 ×10⁹/L (150,000 per microliter, or 150 K/µL on many US reports) is low. Platelets are the cell fragments that plug a cut, and most people with a mildly low count (100 to 149) feel nothing and never bleed more than anyone else. A low count becomes a worry when it is very low, when it drops quickly, or when it is not the only line on the blood count that is off. A stable count of 120 with a normal rest of the blood count is usually harmless; the same 120 is a concern if it was 250 last week.
For the normal range and what platelets do, see the parent page on platelet count. This page covers the low side only.
Where an example count of 70 falls×10⁹/L
How low is too low?
| Count (×10⁹/L) | Grade | What it usually means | Typical next step |
|---|---|---|---|
| 100 to 149 | Mild | No extra bleeding; common in healthy people | Repeat the count in 2 to 4 weeks; check the rest of the complete blood count (CBC) |
| 50 to 99 | Moderate | Bleeding is unusual; 50 or more is generally adequate for many procedures 1, but your care team sets the threshold | Smear, medication and alcohol review, cause work-up |
| 20 to 49 | Severe | Bruising and bleeding after injury become more likely | Medical review within days; same day if falling or bleeding |
| Under 20 | Very severe | Spontaneous bleeding risk rises, especially under 10 | Same-day medical care |
The cause changes the risk at any given number. In immune thrombocytopenia (ITP, where antibodies clear platelets early) the remaining platelets are young and work well, so people bleed less than the count suggests. After chemotherapy, the same count carries more risk.
First, make sure the low count is real
About 1 in 1,000 blood samples shows pseudothrombocytopenia: platelets clump together in the purple-top EDTA tube, the analyzer counts each clump as one, and the result reads falsely low. A blood smear shows the clumps, and a recount in a citrate tube gives the true number 1. If you feel well, have no bruising and the rest of the blood count is normal, a recount is the usual first step.
One result is also a single snapshot. Platelets live 7 to 10 days, so a recent virus can dip the count for a week or two; if you have just had a cold or flu, a repeat count 2 to 4 weeks later usually shows whether it bounces back. Women average higher counts than men, counts drift down with age and vary by ancestry, and each lab sets its own range, so a 145 on one report may sit inside another lab's normal. Two short reads help here: why trends beat single readings and how reference ranges are set.
What causes low platelets
Common causes
- Heavy alcohol use, which slows platelet production in the marrow; the count often recovers within one to two weeks of stopping 1.
- Liver disease and an enlarged spleen. The spleen normally holds about a third of the body's platelets; in cirrhosis or advanced fatty liver disease the spleen swells and holds more back 1.
- Recent viral infections, including flu, COVID-19, Epstein-Barr virus and, in travelers, dengue. Fever with a low or falling platelet count after travel to a dengue area needs same-day medical care.
- Medicines. Heparin, quinine (even a small amount of tonic water can trigger it in someone sensitized), some sulfa antibiotics and some seizure drugs can cause an immune drop, usually 5 to 10 days after starting 1. Valproate and linezolid lower platelets more gradually, with higher doses or longer use. If you take one of these and your count is low, raise it with your prescriber rather than stopping the medicine yourself.
- Pregnancy, through gestational thrombocytopenia (covered below).
- Vitamin B12 or folate deficiency, which starves the marrow of what it needs to make all blood cells. See B12 deficiency.
Less common causes
- Immune thrombocytopenia (ITP), defined as a count under 100 with no other cause found 2.
- Autoimmune disease such as lupus, and chronic infections such as HIV and hepatitis C.
- Chemotherapy and radiation.
- Marrow diseases: leukemia, lymphoma, myelodysplasia and aplastic anemia. These usually lower more than one cell line.
Must-not-miss causes
- Heparin-induced thrombocytopenia (HIT): the count falls by more than half 5 to 10 days after starting heparin, and clotting risk goes up, not down 5. Anyone on heparin whose count drops this way needs their care team that day.
- Thrombotic thrombocytopenic purpura (TTP) and hemolytic uremic syndrome (HUS): small clots form throughout the blood vessels, using up platelets and shredding red cells as they pass. The signs are low platelets with anemia and fragmented red cells on the smear, often with confusion, fever or kidney trouble. TTP is a medical emergency 6.
- Disseminated intravascular coagulation (DIC), where severe infection, trauma or a pregnancy complication uses up platelets and clotting factors at once.
- HELLP syndrome (hemolysis, elevated liver enzymes and low platelets, a severe form of pre-eclampsia): a sudden platelet drop in late pregnancy or in the days after delivery, with high blood pressure and abnormal liver tests.
Symptoms of low platelets
Most low platelet counts cause no symptoms and turn up on a routine blood count. When the count is low enough to show, the signs are bleeding signs: petechiae (pinpoint red or purple dots that do not fade when pressed, often on the shins), easy bruising, bleeding gums, nosebleeds, heavy periods and cuts that keep oozing. Blood in urine or stool is less common and needs checking. Tiredness is not a platelet symptom; when it comes with a low count it usually reflects the cause, or anemia alongside.
Reading low platelets with the rest of your blood count
Your marrow makes three cell lines: red cells (measured as hemoglobin), white cells and platelets. A low platelet count alone points toward the common, contained causes: a recent virus, a medicine, alcohol, the spleen, ITP or pregnancy. A low platelet count with low hemoglobin, low white cells or both points toward the marrow, B12 or folate deficiency, or a large spleen, and gets a faster work-up. Our guide to the full blood count walks through every line.
| Pattern on the report | What it leans toward |
|---|---|
| Low platelets, high MPV | Platelets being cleared early with the marrow working hard to replace them, as in ITP |
| Low platelets, low or normal MPV | A production problem in the marrow |
| Low platelets, fragmented red cells on the smear | TTP or HUS until proven otherwise; needs same-day care |
| Low platelets, low hemoglobin and low white cells | Marrow problem, B12 or folate deficiency, or enlarged spleen |
MPV (mean platelet volume, the average size of platelets) supports a direction but does not settle it on its own.
Read these beside your platelet count
CalculatorAbsolute neutrophil count calculatorIf white cells are low too, this shows whether the infection-fighting part is low.Work it out What usually happens next
For a newly found low platelet count, a doctor usually starts with a repeat blood count and a blood smear, then a review of every medicine, supplement and alcohol intake. The next tests depend on the pattern: B12 and folate, liver tests, HIV and hepatitis C (what viral tests show), and clotting tests (prothrombin time, fibrinogen, D-dimer) if the count may be getting used up. An ultrasound can measure the spleen. Referral to hematology is common when the count stays under 100, keeps falling or comes with other abnormal lines 1. Clotting tests are explained in what clotting tests measure, and liver results in liver enzymes explained.
Useful questions to ask: Can we repeat it with a smear, and a citrate tube if clumping is possible? Could any of my medicines or supplements cause this? When should we recheck, and at what number would you refer me to hematology?
Tests a doctor often adds
When the count is mildly low, stable and nothing else is wrong, the usual plan is watchful monitoring. In the largest follow-up of this group, 217 healthy adults with an isolated count of 100 to 150 were tracked for up to 10 years; the 10-year chance of developing ITP below 100 was 6.9%, about 12% developed another autoimmune condition, and most stayed stable or returned to normal 3. Even with confirmed ITP, the ASH guideline leans toward watching rather than treating when the count is 30 or above and bleeding is minor or absent:
In adults with newly diagnosed ITP and a platelet count of ≥30 × 10⁹/L who are asymptomatic or have minor mucocutaneous bleeding, the ASH guideline panel suggests against corticosteroids and in favor of management with observation.American Society of Hematology 2019 guidelines for immune thrombocytopenia 2
In plain words: if the count is 30 or more and you only have small bruises or pinpoint spots on the skin or gums, the guideline suggests watching rather than starting steroids.
Can you increase your platelet count naturally?
You can increase a low platelet count naturally only by fixing what is lowering it. Counts usually recover when heavy drinking stops, when a doctor stops or switches a culprit drug (counts often recover within days to weeks), when an infection clears, and when a proven B12 or folate deficiency is treated. Do not stop a prescribed medicine, including heparin, blood thinners or seizure medicines, without speaking to the prescriber first. No food, juice or supplement reliably raises platelets in someone who is not deficient. Treatment for ITP or marrow disease is a decision for a hematologist.
Supplements a doctor may use when a test shows a deficiency
Low platelets in pregnancy and in children
Gestational thrombocytopenia affects about 5 to 10% of pregnancies and explains around three quarters of low platelet counts in pregnancy. It appears late, is usually mild (often above 70 to 80), is not linked to bleeding problems for mother or baby and usually resolves after delivery 4. A lower count, an early drop, or a drop with high blood pressure in pregnancy or after delivery points instead to pre-eclampsia, HELLP or ITP, and needs the obstetric team promptly.
In children, low platelets most often mean acute ITP a few weeks after a viral infection: sudden bruising and petechiae in a child who otherwise looks well. Most children recover within 12 months, many without treatment 2. A child with low platelets who also has fever, pallor, bone pain, weight loss, swollen glands, or low hemoglobin or white cells needs prompt medical review, because these point away from ITP toward the marrow, including leukemia.
For the other lines on the same report, see the blood count hub.
Citations
- Gauer RL, Whitaker DJ. Thrombocytopenia: evaluation and management. Am Fam Physician. 2022;106(3):288-298
- Neunert C et al. American Society of Hematology 2019 guidelines for immune thrombocytopenia. Blood Adv. 2019;3(23):3829-3866
- Stasi R et al. Long-term outcome of otherwise healthy individuals with incidentally discovered borderline thrombocytopenia. PLoS Med. 2006;3(3):e24
- American College of Obstetricians and Gynecologists. Practice Bulletin No. 207: Thrombocytopenia in pregnancy. Obstet Gynecol. 2019;133(3):e181-e193
- Cuker A et al. American Society of Hematology 2018 guidelines for management of venous thromboembolism: heparin-induced thrombocytopenia. Blood Adv. 2018;2(22):3360-3392
- Zheng XL et al. ISTH guidelines for the diagnosis of thrombotic thrombocytopenic purpura. J Thromb Haemost. 2020;18(10):2486-2495
Educational context only, not medical advice or a diagnosis. Always discuss your results with a clinician.
