Increased mean corpuscular hemoglobin concentration: A case report as an early clue of chronic severe hyponatremia.
Jianping Chen, Shi Chen, Xinzheng Li et al.
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Case in brief
An 81-year-old woman was admitted after three days of altered mental status. Her complete blood count showed a markedly elevated mean corpuscular hemoglobin concentration (MCHC) of 369 g/L; the blood smear showed reduced central pallor and mildly hyperchromic erythrocytes, consistent with cellular dehydration. After common analytical interferences were excluded, the elevation prompted an early laboratory warning. Testing identified chronic severe hypotonic hyponatremia, with serum sodium of 102 mmol/L. After targeted sodium replacement, sodium normalized to 142 mmol/L, mental status improved markedly, and MCHC fell to 337 g/L.
What made this case unusual
A confirmed true MCHC elevation, rather than an analytical artifact, served as an early clue to severe chronic hyponatremia before biochemical results were available.
Diagnostic / clinical pearl
When MCHC is genuinely elevated, exclude common analytical interferences and consider chronic hyponatremia, particularly when the smear suggests erythrocyte dehydration.
Why it matters
Prompt communication between laboratory personnel and clinicians may help expedite recognition and treatment of a critical electrolyte disorder.