A 52-year-old man is brought to the emergency department by his daughter due to a fall while climbing stairs. He has mild pain in his right arm but no other obvious injuries. The patient has had frequent stumbling and near-falls over the last 2 months. He has also had significant fatigue, chronic abdominal pain, constipation, and recurrent headaches as well as a "pins-and-needles sensation" in his palms and soles. His daughter notes he has been more forgetful recently. The patient has smoked a pack of cigarettes daily for 20 years and drinks beer on weekends. A year ago, he started work as a janitorial custodian at a battery manufacturing plant and finds his job moderately stressful. The patient has not had regular medical follow-ups. Blood pressure is 160/90 mm Hg, and pulse is 84/min. The abdomen is soft and nontender, and no masses are palpable. There is mild tenderness over the right middle ulna with normal range of motion at the wrist and elbow. Neurological evaluation shows reduced pinprick sensation bilaterally in hands and feet. There is weakness of adduction and abduction of the fingers and of bilateral thigh and knee extensors. The patient has a wide-based gait and is unable to tandem walk. Laboratory results are as follows: Which of the following is the most likely diagnosis for this patient's clinical presentation?

Question

A 52-year-old man is brought to the emergency department by his daughter due to a fall while climbing stairs.  He has mild pain in his right arm but no other obvious injuries.  The patient has had frequent stumbling and near-falls over the last 2 months.  He has also had significant fatigue, chronic abdominal pain, constipation, and recurrent headaches as well as a "pins-and-needles sensation" in his palms and soles.  His daughter notes he has been more forgetful recently.  The patient has smoked a pack of cigarettes daily for 20 years and drinks beer on weekends.  A year ago, he started work as a janitorial custodian at a battery manufacturing plant and finds his job moderately stressful.  The patient has not had regular medical follow-ups.  Blood pressure is 160/90 mm Hg, and pulse is 84/min.  The abdomen is soft and nontender, and no masses are palpable.  There is mild tenderness over the right middle ulna with normal range of motion at the wrist and elbow.  Neurological evaluation shows reduced pinprick sensation bilaterally in hands and feet.  There is weakness of adduction and abduction of the fingers and of bilateral thigh and knee extensors.  The patient has a wide-based gait and is unable to tandem walk.  Laboratory results are as follows:  Which of the following is the most likely diagnosis for this patient's clinical presentation?

Quizplus · Accepted Answer

Explanation: 11ec25c8_d1bc_5476_bc81_d79ae90738bf_MD0003_00 This patient likely has lead toxicity due to occupational exposure in a battery manufacturing plant. In addition to his clinical presentation consisting of nonspecific general manifestations (eg, fatigue), other features include: Neuropsychiatric manifestations (eg, short-term memory loss, sensorimotor neuropathy, headaches, ataxia) Gastrointestinal manifestations (eg, abdominal pain, constipation) Hypertension and possible nephrotoxicity (eg, elevated creatinine) Inhibition of enzymes responsible for heme and RNA synthesis in both bone marrow and mature erythrocytes can lead to microcytic anemia with basophilic stippling, and impaired purine metabolism can result in hyperuricemia, both seen in this patient. basophilic stippling Once absorbed (in adults, predominantly via the lungs), lead distributes throughout the blood, bones, and other organs, affecting cell function throughout. Lead is predominantly stored in the skeleton and is released slowly, potentially exerting its pathologic effects over decades. Diagnosis depends on establishing a history of lead exposure accompanied by corroborating physical examination findings (eg, neurologic manifestations) and elevated blood lead levels. Removal from the lead source and chelation therapy is the treatment for those with symptoms and/or markedly elevated levels. (Choice A) Alcohol abuse is associated with peripheral neuropathy and occasionally ataxia and hyperuricemia. However, it is also associated with macrocytic anemia and transaminase elevations, which are not present in this patient. (Choice B) When chronically uncontrolled, diabetes mellitus is associated with peripheral neuropathy (usually with more sensory than motor deficits), nephropathy, and retinopathy. It is not associated with microcytic anemia. (Choice C) Hypothyroidism can cause sensory neuropathy and may be associated with motor weakness and hyperuricemia. However, anemia due to hypothyroidism is generally either normocytic or macrocytic, and without reticulocytosis. (Choice E) Parkinson disease clinically presents with "pill-rolling" tremor, bradykinesia, rigidity, and postural instability. Gait is shuffling rather than ataxic. Parkinson disease alone is associated with autonomic dysfunction but not usually peripheral neuropathy, anemia, hyperuricemia, or nephropathy. (Choice F) Pernicious anemia is an autoimmune disease targeting intrinsic factor and/or parietal cells, resulting in B₁₂ malabsorption. Subsequent B₁₂ deficiency may result in megaloblastic (macrocytic) anemia, dementia, and subacute combined degeneration with progressive weakness, spasticity, and incontinence. ₁₂ ₁₂ Educational objective: Chronic lead toxicity in adults presents with neuropsychiatric, gastrointestinal, and general symptoms including peripheral sensorimotor neuropathy, fatigue, abdominal pain, and constipation. It can lead to hypertension, nephropathy, hyperuricemia, and microcytic anemia with basophilic stippling seen on the peripheral smear. Diagnosis hinges on a thorough history including potential sources of lead exposure. References: Evaluation and management of lead exposure. (http://www.ncbi.nlm.nih.gov/pubmed/26677413)

A 52-Year-Old Man Is Brought to the Emergency Department by His