High MPV: what large platelets mean on your blood test

Mean platelet volume is the average size of the platelets in your blood sample, measured by the same machine that counts them. An MPV of 12 or 13 fL with an H beside it means the platelets in that tube were on the large side. What large platelets mean depends almost entirely on one neighbouring line of the report, the platelet count, and read together they usually show whether it matters.

For what MPV is, its full normal range and what a low result means, see the parent page on mean platelet volume. This page covers the high side only.

What a high MPV measures

MPV is reported in femtolitres (fL), a tiny unit of volume; a typical platelet measures about 7.5 to 11.5 fL. Platelets are the cell fragments that plug a cut, and they last only about a week to 10 days in the blood, so the bone marrow (where blood cells are made) replaces them constantly. Newly released platelets are larger than older ones. When the marrow speeds up output, for example to replace platelets that are being destroyed or lost, the average size on the report goes up.

In many healthy people, MPV and platelet count tend to move in opposite directions: someone with a platelet count at the low end of normal often has slightly larger platelets. That is one reason a borderline-high MPV is so often nothing. The machine matters too. Different lab machines measure platelet size in different ways, and there is no agreed standard between them, so the same blood can read higher at one lab than another ¹. A 12.0 at one lab and an 11.2 at another may describe identical platelets.

What an MPV of 11, 12 or 13 fL means

The table below groups MPV results into plain bands. These bands are our reading aid, not a guideline; machines differ ¹, so use your own lab's range first.

So an MPV of 12, 12.7 or 13 fL, with a platelet count between 150 and 450 ×10⁹/L (the usual units on a blood count, often printed as 150 to 450, or 150 to 450 K/µL) and no unusual bleeding or bruising, is most often a result to watch over time. A single high reading says less than the direction over two or three tests; see why trends beat single readings.

Three patterns with your platelet count

The platelet count tells you whether a high MPV reflects a marrow responding to a problem or a marrow at rest with slightly bigger platelets. In a study comparing immune thrombocytopenia (ITP, where the immune system destroys platelets) with aplastic anaemia (where the marrow makes too few), MPV, platelet distribution width and the large-cell ratio were all higher in ITP ². Large platelets alongside a low count therefore point toward platelets being cleared faster than normal.

If ferritin comes back low, see iron deficiency; iron studies explained walks through the rest of the iron panel.

Common causes of a high MPV

• Immune thrombocytopenia. The platelet count is low, sometimes with easy bruising or pinpoint red spots on the skin, and the platelets are large because the marrow is replacing destroyed ones ².
• Recovery after bleeding, surgery, chemotherapy or a severe infection. The marrow rebounds and releases a wave of young platelets; MPV settles over the following weeks.
• Inflammation and infection. An hs-CRP result alongside the blood count shows whether inflammation is part of the picture.
• Type 2 diabetes and poor glucose control. In US national survey data on 13,021 adults, average MPV was 8.20 fL in people with diabetes against 8.06 fL without, and in people with diabetes MPV rose with glucose and A1C ⁵. See type 2 diabetes.
• Smoking, which some studies link to larger platelets.
• An overactive thyroid, reported in some studies. A TSH (thyroid-stimulating hormone) test checks for it; see hyperthyroidism.
• Inherited giant-platelet disorders such as Bernard-Soulier syndrome and MYH9-related disease. These give a lifelong low count with very large platelets, often run in families, and are easily mistaken for ITP. A blood smear is recommended in ITP work-ups partly to catch them ³.
• Preeclampsia in pregnancy, where platelets are used up faster. A high MPV or falling platelet count in pregnancy together with high blood pressure, severe headache, vision changes or pain under the ribs needs same-day care.

Could it be the sample, not you?

Platelets swell in the purple-top EDTA tube used for blood counts, so MPV creeps up the longer a sample waits before the analyzer reads it ¹. A sample drawn at a clinic in the morning and run in the afternoon can read higher than the same blood run within the hour.

In some people, platelets clump together in EDTA, an uncommon lab effect called EDTA-dependent pseudothrombocytopenia. It comes from natural antibodies, can persist for years and causes no disease ⁶. The clumps are counted as single large particles or missed altogether, so the platelet count reads falsely low and the MPV can read oddly high or be withheld. Some labs withhold the MPV result when the count is very low or clumps are flagged.

Is a high MPV a sign of heart disease or cancer?

On average, people having a heart attack have slightly larger platelets. A meta-analysis pooling 16 studies of 2,809 people found MPV was 0.92 fL higher in people with a heart attack than in people without, and a higher MPV was linked to a higher risk of death afterwards ⁴.

Whether the relationship is causal, and whether MPV should influence practice or guide therapy, remains unknown.Chu SG et al., Journal of Thrombosis and Haemostasis, 2010 ⁴

A group difference of under 1 fL, often smaller than the gap between two lab machines, cannot sort one person into high or low risk. MPV is not used to screen for or diagnose heart disease. Blood pressure, LDL cholesterol, A1C (average blood sugar over about three months) and smoking status say far more about your heart than platelet size does.

A high MPV alone is not a sign of cancer. Blood cancers usually show up through other changes on the blood count, such as very high or very low white cells, low hemoglobin (anemia), abnormal cells on the smear, or a platelet count far outside the range. An isolated MPV of 12 or 13 fL with an otherwise normal blood count does not, on its own, point toward cancer; your doctor reads it with the rest of your results.

The other platelet numbers on your report

Platelet distribution width (PDW) and the platelet large cell ratio (P-LCR) both usually rise with MPV, so three high results together describe the same large platelets, and with a normal count they add nothing new. A high RDW on the same report concerns red cells, not platelets, and is read separately.

What to do next

1. 1Normal platelet count and you feel wellUsually no action is needed for the high MPV itself, unless your doctor has flagged it for another reason. Compare it at your next routine blood count, ideally at the same lab, since machines differ.
2. 2Low platelet count, or bruising or bleedingAsk your doctor about a repeat blood count and a blood smear, which rules out clumping in the tube and inherited giant platelets ³. If the count is under about 50 ×10⁹/L, or you have new bruising, pinpoint red spots, gum or nose bleeding, or fever, contact your doctor promptly rather than waiting for a routine visit; bleeding that will not stop needs emergency care.
3. 3Tests that may follow, depending on the pictureFerritin and iron studies, vitamin B12 and folate, TSH, hs-CRP and A1C. Ask your clinician which of these fits your results; a repeat count in 4 to 8 weeks shows whether MPV is settling.

To lower MPV, treat what is raising it. MPV runs higher with poorer glucose control in people with diabetes ⁵, so managing blood sugar with your doctor addresses one known driver, and stopping smoking removes another reported one. No supplement has evidence for lowering MPV, and chasing the number itself is pointless when the platelet count is normal.

Read the rest of your blood count

A single H beside MPV means more next to the other lines of the blood count. The complete blood count explainer walks through every line, lab report flags explained covers what H and L do and do not mean, and the blood count topic gathers every marker on it.

Free, no accountRead your blood testRead MPV beside your platelet count and every other line of your blood count.Read my results

Free, no accountDrop in your lab report and see every marker explained in plain words, placed on the body, against your lab's range. It's read on your device: nothing is uploaded and nothing is kept.

Read my results Download the app