Case Presentation: A 68-year-old woman was initially evaluated for severe macrocytic anemia in June 2025, with a hemoglobin level of 4.8 g/dL. She was diagnosed with vitamin B12 deficiency (154 pg/mL) and started on intramuscular B12 injections. Her hematological profile normalized within 2-4 weeks. 6 weeks after starting B12 treatment, she developed progressive loss of sensations and weakness in her right leg, which worsened into right foot drop over the next month. Neurological exam showed: Loss of vibration sense in both legs, Upgoing Babinski reflex on the right, Nerve conduction studies revealed bilateral L5 radiculopathy with signs of subacute to chronic denervation. Her work up revealed Severe Copper Deficiency with undetectable copper levels (< 5 mcg/dl). She required IV copper infusions in the hospital and starting nearly 5-7 days into the treatment - She noticed some changes every 12 hours - findings like improving sensations, electric sensation , spasms and slow improvement in the ability to more her toes. Extensive workup for autoimmune diseases, malabsorption, celiac disease, and lumbar puncture were all negative. Zinc levels during admission were normal.
Discussion: On retrospective questioning, she reported taking zinc supplements 3–4 times a week for about 5 years, starting during the COVID-19 pandemic. Although she stopped zinc 1 year prior to the presentation, the long-term use likely led to copper depletion. Her neurological symptoms may have been unmasked after correcting the B12 deficiency. She was also on a proton pump inhibitor (PPI), which may have further impaired copper absorption.
Conclusions: This case highlights the delayed neurological consequences of chronic zinc supplementation, even after discontinuation. It emphasizes the need to consider trace mineral deficiencies, especially copper, in patients with unexplained neurological symptoms and a history of supplement use. This also highlights the delicate balance of micro-nutrients and reversibility of copper myelopathy with early and aggressive correction. May be every other day zinc supplementation for 4 years is enough to cause severe copper deficiency.
