Should You Be Concerned About These Lab Values?
Yes, you should be concerned and pursue investigation—this patient in their early 60s has mild anemia with an abnormally elevated MCHC (40.1) and significant thrombocytosis (558), which warrants workup for iron deficiency anemia and exclusion of underlying gastrointestinal pathology, particularly malignancy given their age. 1
Key Laboratory Abnormalities
The lab values reveal several concerning findings:
- Mild anemia (Hb 10.7 g/dL) with low MCH (25.5) suggests microcytic anemia, most commonly iron deficiency 1
- Elevated MCHC (40.1) is abnormal and may indicate laboratory artifact, hemolysis, or spherocytosis—this requires peripheral blood smear review 1
- Thrombocytosis (558 × 10^9/L) is significant and commonly associated with iron deficiency anemia, occurring in approximately 22% of IDA patients 2
Critical Age-Related Considerations
In patients over 60 years with iron deficiency anemia, the probability of gastrointestinal malignancy is substantially higher, and dual pathology is more common. 1
- The median age at presentation for IDA is over 70 years, and older patients have increased risk of serious GI pathology including malignancy 1
- Age is the strongest predictor of pathology in patients with IDA 1
- Bidirectional endoscopy (BDE) with duodenal biopsy is the appropriate investigational approach for older subjects with IDA 1
Recommended Diagnostic Workup
Immediate Steps
- Obtain peripheral blood smear to evaluate the elevated MCHC, assess platelet morphology, and confirm microcytic anemia 1, 3
- Check iron studies (serum iron, ferritin, TIBC, transferrin saturation) to confirm iron deficiency 1
- Screen for celiac disease with anti-tissue transglutaminase (tTG) antibody, as CD is found in 3-5% of patients with unexplained IDA 1
Age-Appropriate Investigation
For this patient in their early 60s, bidirectional endoscopy (upper and lower) with duodenal biopsy should be strongly considered to exclude:
- Gastrointestinal malignancy (colorectal cancer, gastric cancer) 1
- Celiac disease (sensitivity of serology falls with age, reaching as low as 74% in patients with IDA) 1
- Other GI pathology (angioectasia, inflammatory bowel disease, NSAID enteropathy) 1
Understanding the Thrombocytosis
The elevated platelet count is likely reactive thrombocytosis secondary to iron deficiency:
- Iron deficiency commonly causes thrombocytosis, with platelet counts occasionally exceeding 1000 × 10^9/L in severe cases 4, 5
- Thrombocytosis resolves in most patients (about 80%) within 3 months of iron replacement therapy 2
- At this level (558), the thrombocytosis itself poses minimal thrombotic risk—platelet counts >1000 × 10^9/L are actually associated with bleeding risk rather than thrombosis 1, 3
Important Caveat
While reactive thrombocytosis from iron deficiency is most likely, you must exclude primary myeloproliferative neoplasms (essential thrombocythemia, polycythemia vera) if:
- Thrombocytosis persists after iron repletion 3
- Other blood count abnormalities develop 1
- Constitutional symptoms (night sweats, weight loss, pruritus) are present 1
Treatment Approach
Once iron deficiency is confirmed:
- Initiate iron replacement therapy (oral or intravenous depending on severity and tolerance) 1
- Monitor response with complete blood count at 3,6,12, and 24 months after iron repletion 1
- Expect platelet count to decrease with iron replacement—this occurs in approximately 72% of patients regardless of baseline thrombocytosis 2
Critical Pitfalls to Avoid
- Do not attribute the anemia solely to age or chronic disease without investigating for iron deficiency and underlying GI pathology 1
- Do not delay endoscopic investigation in this age group—the risk of malignancy is too significant 1
- Do not assume thrombocytosis is benign without confirming it resolves with iron replacement 3, 2
- Do not overlook the abnormal MCHC—this requires peripheral smear review to exclude hemolysis or other red cell abnormalities 1