Case Presentation: A 68- year-old Hispanic male with past medical history of hypertension, hyperlipidemia and gout presented with intermittent paresthesia and weakness in bilateral fingers and toes along with mild headaches and fatigue for the past two months. Additionally, the patient notes to have new short-term memory deficits where he often forgets his thoughts mid-conversation. He reports to starting a sanding project in which he was renovating old furniture roughly 2.5 months ago. He currently lives in a house which was built in the 1890s but the establishment has been re-painted and renovated multiple times since it was built. Neurological exam exhibited 5/5 strength in upper and lower extremities with no sensory deficits to fine touch, proprioception or vibration. MMSE was 29/30. Laboratory results showed Hgb: 14.2 g/dL, Erythrocyte Metal-Free Protoporphyrin 74%, and Lead Blood at 54 ug/dL. This case was discussed with toxicology department and it was determined to start patient on a 19 day treatment course with succimer (2,3-dimercaptosuccinic acid). The patient was scheduled to have 10 mg/kg TID for first five days and then 10 mg/kg BID for the last 14 days. However 10 days into therapy, patient noted to have bilateral knee swelling with severe arthralgia and generalized weakness. Lab work was pertinent with transaminitis greater than three times the upper limit of normal thus it was decided to abort therapy due to side effects. Few days after discontinuation of succimer, he noted to have complete resolution of knee swelling, arthralgia and weakness. Repeat lab work showed lead blood at 2 ug/dL. Additionally, his presenting symptoms of paresthesia and mild headaches also completely resolved. Patient was monitored for subsequent follow up visits in clinic to trend liver enzymes and they normalized in 3 weeks.
Discussion: This case shows the importance of considering lead poisoning as a differential diagnosis in patients with non-specific neurological symptoms. Although this was known as significant problem in the 1960s-1970s due to lead-based paint, lead exposure continues to remain an environmental health problem even after federal regulations restricted the use of lead in household paint in 1978. Most of the cases were usually seen in small children who tend to put chips of peeling paint in their mouth. However, in adults, the respiratory tract is the most significant route of lead absorption with an average rate of approximately 50 percent. Anemia is thought to be the most common presenting sign but usually is seen in lead levels >80 ug/dL. In our patient, he was working on a sanding project for the past few months without taking proper measures to prevent inhalation of particles. Although he developed side effects from succimer particularly transaminitis (roughly seen in 6% of individuals), swelling/arthralgia (seen in less than 1% individuals) and was forced to discontinue therapy early, his presenting symptoms resolved and his blood lead level normalized after chelation therapy and cessation of project.
Conclusions: Lead poisoning can have deleterious effects on a person’s health if not identified and treated appropriately. It is important to further investigate a person’s hobbies, occupational history and living environment in cases of non-specific neurological symptoms to determine if lead poisoning is the culprit.