Microcytosis Merits Evaluation: A Case Report of Hemoglobin S With Hereditary Persistence of Fetal Hemoglobin (HbS-HPFH Syndrome).

Microcytosis is commonly encountered in primary care. Among patients with normal iron stores or compatible family history, hemoglobin electrophoresis, traditionally performed with gel electrophoresis and now through combination capillary electrophoresis/high-performance liquid chromatography, can diagnose thalassemic disorders or, rarely, a hemoglobinopathy. We present a case of an incidentally discovered microcytosis in a 34-year-old male patient where the workup led to a diagnosis of Hemoglobin S with Hereditary Persistence of Fetal Hemoglobin (HbS-HPFH syndrome). The diagnosis led providers to re-evaluate the patient's chronic hip pain, upon which the patient was found to have bilateral osteonecrosis of the femurs. Microcytosis is a lab abnormality that is often asymptomatic and, therefore, may be ignored or overlooked. When encountering microcytosis in primary care, it is important to identify the etiology using a brief, targeted approach. This may directly impact management and can prove helpful when considering future complaints of the patient.