Clinical Significance of Mildly Elevated MCV and MCH in an Asymptomatic Adult Female
These mildly elevated values (MCV 98 fL, MCH 33.1 pg) in the context of completely normal hemoglobin, hematocrit, and RBC count are clinically insignificant and require no immediate intervention. This represents a normal physiological variant that does not indicate anemia, polycythemia, or any pathological condition requiring treatment.
Understanding the Laboratory Pattern
Your complete blood count shows all critical parameters within normal ranges: hemoglobin 16.9 g/dL (normal 13.0-17.7), hematocrit 49.7% (normal 37.5-51.0), and RBC count 5.10 (normal 4.14-5.80) 1
The MCV of 98 fL is only 1 fL above the upper limit of 97 fL, and MCH of 33.1 pg is only 0.1 pg above the upper limit of 33.0 pg—these are trivial elevations that fall within biological and analytical variation 2
MCHC is completely normal at 34.0 g/dL (normal 31.5-35.7), which is the most important red cell index for detecting spurious results or true pathology 2
RDW is normal at 13.6% (normal 11.6-15.4%), which effectively excludes iron deficiency, vitamin B12/folate deficiency, or any mixed red cell population 3
Why These Values Are Not Concerning
Macrocytosis (MCV >100 fL) typically indicates vitamin B12 or folate deficiency, alcoholism, myelodysplastic syndrome, or certain medications like hydroxyurea 3
Your MCV of 98 fL does not meet criteria for macrocytosis, which requires MCV >100 fL according to standard hematologic definitions 3
In the context of normal hemoglobin and hematocrit, slightly elevated MCV and MCH have no association with adverse outcomes and do not predict anemia development 4
Studies evaluating MCV and MCH as screening tools show that values just above the reference range have poor positive predictive value for detecting underlying pathology when other parameters are normal 5
What This Pattern Does NOT Indicate
Not vitamin B12 or folate deficiency: These conditions cause MCV typically >110 fL with associated anemia, neither of which is present 3
Not early iron deficiency: Iron deficiency causes low MCV and MCH, not elevated values, and your normal RDW excludes this diagnosis 3
Not myelodysplastic syndrome: MDS requires cytopenias in at least one cell line, dysplastic morphology, and typically MCV >100 fL with anemia 3
Not polycythemia vera: Your hemoglobin 16.9 g/dL and hematocrit 49.7% are well below diagnostic thresholds (Hb >16.5 g/dL, Hct >48-49% in women), and polycythemia vera does not cause isolated MCV/MCH elevation 1
Not hemochromatosis: While hemochromatosis can cause elevated MCV and MCH, it requires values substantially above normal (typically MCV >101 fL, MCH >34 pg) with other clinical features 5
Analytical and Physiological Considerations
Automated analyzer variation: MCV and MCH measurements have inherent analytical variability of ±2-3%, meaning your values of 98 fL and 33.1 pg could represent normal biological variation 2
Sample storage effects: Prolonged sample storage can falsely increase MCV by 2-4%, though this does not affect hemoglobin measurement 1
Hyperglycemia effects: Elevated glucose can falsely increase MCV and calculated hematocrit but does not affect hemoglobin or MCH 1
Normal physiological range: Population studies show that approximately 2.5% of healthy individuals will have values slightly outside reference ranges by statistical definition 1
Recommended Management Approach
No further testing or intervention is needed at this time. Specifically:
Do not order vitamin B12, folate, methylmalonic acid, or homocysteine levels—these are unnecessary with normal hemoglobin and minimal MCV elevation 3
Do not order iron studies, ferritin, or transferrin saturation—your normal RDW and MCHC exclude iron-related disorders 3
Do not order JAK2 mutation testing or erythropoietin levels—your hemoglobin and hematocrit are normal, excluding polycythemia vera 1
Do not order bone marrow biopsy or peripheral blood smear review—there are no cytopenias or abnormal cell counts suggesting myelodysplasia 3
Do not restrict alcohol intake or modify diet based on these values alone—there is no evidence of pathology requiring lifestyle modification 3
When to Reassess
Repeat CBC only if symptoms develop, such as fatigue, weakness, pallor, or bleeding, which would suggest evolving anemia 3
Routine monitoring is not indicated for asymptomatic individuals with this laboratory pattern 3
If MCV increases to >100 fL on future testing with development of anemia, then evaluate for vitamin B12/folate deficiency or myelodysplastic syndrome 3
Common Pitfalls to Avoid
Do not over-investigate minimal laboratory abnormalities in asymptomatic patients with otherwise normal complete blood counts—this leads to unnecessary testing, patient anxiety, and healthcare costs 3
Do not use separate reference ranges for MCV and MCH based on sex, as these indices show no significant gender differences unlike hemoglobin and hematocrit 6
Do not assume that values just outside reference ranges indicate pathology—reference ranges are typically set at 95% confidence intervals, meaning 5% of healthy individuals will have "abnormal" values 1
Do not order comprehensive metabolic panels, liver function tests, or thyroid studies based solely on minimal MCV/MCH elevation without other clinical indicators 3