Iron deficiency anemia: A low Mean Platelet Volume (MPV) can be seen in iron deficiency anemia, which might also cause a slight increase in other parameters due to the body's compensatory mechanisms. However, the CBC being otherwise normal makes this less likely but still a consideration due to the commonality of iron deficiency.

Early or mild thrombocytopenia: Although the CBC is reported as normal, a low MPV could indicate early or mild thrombocytopenia where the platelet count is at the lower end of the normal range or slightly below, and the body is producing smaller platelets.
Recent or mild blood loss: Similar to iron deficiency anemia, recent or mild blood loss could lead to a slight increase in some CBC parameters as the body compensates, and a low MPV might be seen due to the release of younger, smaller platelets into the circulation.
Mild myelodysplastic syndrome (MDS): Some forms of MDS can present with a low MPV and relatively normal CBC, although this would be less common and typically associated with other clinical findings.

Leukemia or lymphoma: Although less likely with a normal CBC, certain types of leukemia or lymphoma could potentially present with a low MPV and a high (marginally) in another parameter. These conditions are critical to diagnose early, making them "do not miss" diagnoses.
Bone marrow failure syndrome: Conditions like aplastic anemia or other bone marrow failure syndromes could have a low MPV and might initially present with near-normal CBC values, especially if the condition is mild or early.
Sepsis or severe infection: In some cases of sepsis or severe infection, platelet parameters can be affected, leading to a low MPV. The CBC might appear normal or near-normal early in the course of the illness.

Wiskott-Aldrich Syndrome: A rare genetic disorder characterized by eczema, thrombocytopenia (with small platelets), and immune deficiency, which could potentially present with a low MPV.
Thrombocytopenia with absent radius (TAR) syndrome: Another rare genetic disorder that affects platelet production and could result in a low MPV, although it typically presents with more significant thrombocytopenia and physical abnormalities.
Other rare platelet disorders: Such as platelet function disorders or congenital thrombocytopenias, which might present with abnormal platelet parameters including a low MPV.