An 18-year-old woman presented with fever, chills, back pain, lightheadedness on standing, and weakness. Six weeks earlier, she had given birth to a full-term infant by spontaneous vaginal delivery complicated by uterine atony and anemia, presumed to have been caused by blood loss. She began receiving iron supplementation. Her medical history included only a spinal fusion for scoliosis. On presentation, the blood pressure was 133/66 mm Hg, body temperature was 39 °C, pulse was 140 beats/min, and respiratory rate was 32 breaths/min. The patient appeared weak and pale. Cardiac examination revealed tachycardia with a II/VI systolic murmur. Results of lung and abdominal examination were normal, but mild costovertebral tenderness was noted on examination of the back. Microscopic urinalysis showed many leukocytes and bacteria. The initial hemoglobin concentration was 7.4 mg/dL.

The patient received intravenous ceftriaxone for pyelonephritis. Anemia studies were obtained before the patient received 2 units of packed red blood cells. The hemoglobin concentration improved to 8.3 mg/dL after transfusion, but the patient remained profoundly fatigued. An additional transfusion was given. The anemia studies subsequently revealed a reticulocyte count of 1.7%, a ferritin concentration of 88.4 mg/dL, and a vitamin B₆ level of 0.9 ng/mL (reference range, 3 to 20 ng/mL), confirming a diagnosis of vitamin B₆ deficiency. The patient briefly received supplemental pyridoxine therapy, and her hemoglobin concentration returned to normal after several weeks.

Clinical disease caused by a deficiency of vitamin B₆, including pyridoxine, pyridoxamine, and pyridoxal, is rare [1]. Vitamin B₆ deficiency may impair immune response [2] and may cause a microcytic hypochromic anemia [3]. It may also cause dermatitis, neuritis, stomatitis, cheilosis, glossitis, irritability, depression, and confusion in adults [4]. Although most cases of postpartum anemia are related to blood loss [5], this case was unusual because vitamin B₆ deficiency complicated the patient's treatment. We have found no other description in the literature of an association between vitamin B₆ deficiency, which in itself is rare, and refractory postpartum anemia.