Case

Case Study Thirty-five-year-old carpenter

A 35 year-old male presents because of numbness and tingling of his hands and feet.

History of present illness: His symptoms began approximately 3 months ago, with gradual onset of numbness and tingling in his toes and fingertips, progressing over weeks to involve the feet and hands in a symmetric "stocking glove" pattern. About 1 month ago he had an episode of nausea, abdominal pain, and diarrhea, which resolved after 3 days. In the past 2 to 3 weeks, the tingling has taken on a progressively painful, burning quality and he has noted weakness in gripping tools.

Past medical history: non-contributory.

Family history is unremarkable; his wife, parents, and two younger brothers are in good health.

Social history: The patient has been a carpenter since completing high school 17 years ago. For the last 10 years, he has lived in a rural, wooded area in a home he built in the wooded foothills of the Cascade Range in Northwest Washington. Approximately 10 months ago, he married and moved with his wife, an elementary school teacher, into a newly built home on an adjacent parcel of land. The patient consumes 1 to 2 alcoholic drinks a week and quit smoking 2 years ago after a 15 pack/year history. He takes 1 multivitamin a day, but no other supplements or prescription medications.

Review of Systems: He notes episodes of increased sweating in the last 3 months.

Physical Examination:

Vital signs: temperature 37. 5 degrees C; pulse 60 and regular; respirations 12; BP 124/76.

Head, Eyes, Ears, Nose, and Throat are within normal limits.

Respiratory, cardiovascular, and abdominal systems are also normal to auscultation and palpation, with no hepatosplenomegaly. There is no lymphadenopathy.

Dermatologic examination reveals brown patches of hyperpigmentation, with scattered overlying pale spots in and around the axillae, groin, nipples, and neck. The palms and soles show multiple hyperkeratotic corn-like elevations 4 to 10 mm in diameter. Three irregularly shaped, sharply demarcated, erythematous, scaly plaques, measuring 2 to 3 cm, are noted on the patient's torso.

Neurologic examination reveals diminished proprioception in the hands and feet, with a hyperesthetic response to pinprick on the soles. Motor bulk and tone are normal, but there is slight bilateral muscular weakness in dorsiflexors of the toes and ankles, wrist extensors, and hand intrinsics. Reflexes are absent at the ankles and 1+ at the biceps and knees. Coordination and cranial nerve function are within normal limits. Joints have full range of motion, with no erythema, heat, or swelling.

The remainder of the physical examination is normal.

On initial laboratory evaluation, the following results came back:

• Complete blood count (CBC):
  • slight macrocytic anemia with hematocrit 35% (normal range 40% to 52%),
  • mean corpuscular volume 111 fL (normal range 80 to 100 fL),
  • white blood cell count (WBC) is 4,300/mm³ (normal range 3,900 to 11,700 /mm³); the
  • differential reveals moderate elevation of eosinophils at 9% (normal range 0% to 4%).
• Basophilic stippling of red cells was seen on blood smear.
• Liver transaminases are slightly elevated.
• Urinalysis and electrolytes, including glucose, blood urea nitrogen, and creatinine, are normal.

Initial Check Questions

1. What additional laboratory testing is indicated by this patient's presentation?
2. The patient's main occupational activities are framing new houses and performing renovations on existing homes. He uses "pressure treated lumber" (treated with a wood preservative) for framing and building exterior decks. He usually heats his home with a wood stove burning scrap lumber from building jobs, most of which is pressure-treated lumber. Water supply to his home is from an artesian well. What potential sources of exposure to arsenic does he have?
3. A 24-hour urine collection shows 320 micrograms total arsenic per gram creatinine and a nerve conduction study shows a sensory-motor peripheral neuropathy with evidence of axon damage. What medical recommendations would you make for this patient?
4. Is his wife at risk for arsenic exposure?

Initial Check Answers

1. Additional evaluation should start with a 24-hour urine collection for arsenic and creatinine, and a nerve conduction study of the lower extremities.

   
   Where total urinary arsenic level is high the patient should be asked about recent consumption of seafood. Generally speaking, the forms of arsenic found in seafood are not toxic to humans. There are two options the clinician can take. One is to request testing for speciation of arsenic (i.e., analysis of organo-arsenicals or different inorganic species, rather than total). The other would be to wait 48 hours after last consumption of seafood and run 24 hour urine for total arsenic. Seafood arsenic should have cleared the body in 48 hours.

   Not all labs that perform arsenic levels also can perform speciation. If your laboratory does not perform this test, you may wish to consult your local Poison Control Center for this information.

   In addition, not all labs adjust the arsenic value per gram of creatinine which accounts for the dilution or concentration of the sample. This adjustment may give a more accurate measure of arsenic excretion when incomplete 24 hour or spot urine samples are analyzed.

   More information for this answer can be found in the "Clinical Assessment" section.

2. He may have inhalational and dermal exposure to arsenic compounds used in pressure treating lumber as a preservative, both from inhaling sawdust and handling the lumber. He may have additional exposure to arsenic from inhaling smoke or fumes from scrap lumber burned in his home. He may have ingestion exposure from drinking artesian well water, which may contain higher-than-normal levels of arsenic from underground mineral deposits.

   More information for this answer can be found in the “Where is Arsenic Found?”, “What are Routes of Exposure to Arsenic?”, and “Who is at Risk of Overexposure to Arsenic?” sections.

3. This is an abnormally high amount of total arsenic excretion which may indicate excessive exposure. However, a history of recent seafood ingestion should be taken and the 24 hour urine for total arsenic can be run again in 48 hours after seafood ingestion ceases. Or, a speciated arsenic testing would give information on inorganic vs. organic forms of arsenic.

   Given the chronicity of his symptoms, initial management will be to remove him from arsenic exposure and monitor his clinical course. He has normal renal function, and thus is able to excrete arsenic rapidly. Monitoring might include repeating his urine arsenic testing after an interval of time away from exposure, to assure that excretion (and thus exposure) is decreasing.

   More information for this answer can be found in the “Clinical Assessment” section.

4. His wife drinks from the same well and is exposed to smoke from wood burned in the home. She is at risk for exposure and should be tested with a 24-hour urine collection, even though she is asymptomatic. The same considerations regarding seafood consumption (either repeat of total 24 hour urine arsenic 48 hours after the last seafood meal or ordering speciated arsenic testing) would apply.

   More information for this answer can be found in the “Where is Arsenic Found?”, “What are Routes of Exposure to Arsenic?”, “Who is at Risk of Overexposure to Arsenic?”, and “Clinical Assessment” sections.