Question

Phillip, a 25-year-old male, presented to the hospital emergency department (ED) complaining of headaches, nausea, dizziness, and episodes of repetitive vomiting. He was conscious and denied having chest pain, shortness of breath, abdominal pain, diarrhea, and hematemesis. He also stated that he did not smoke, drink, or use illicit drugs.

While being interviewed further, Phillip did reveal to the clinician that he had attempted suicide in the past and had a history of depression. He was currently taking olanzapine (Zyprexa), which is an antipsychotic and benzodiazepine derivative, and venlafaxine (Effexor), an antidepressant medication, on a daily basis. He also said that he has leukemia.

Phillip also disclosed to the clinician that he had purchased more than 1 gram of the organic form of arsenic trioxide (Trisenox) in liquid form from an Internet auction site for less than $100. Trisenox is a chemotherapeutic agent used to treat various cancers such as leukemia. The drug was shipped to him in an unmarked clear plastic Ziploc bag. He dissolved the drug in water and consumed it about 12 hours before his ED admission.

The results of Phillips’ physical exam including head, eye, ear, nose, and throat (HEENT) revealed nothing abnormal, and his vital signs were normal except for an increased heart rate (tachycardia) of 112 beats/minute. An electrocardiogram revealed a sinus tachycardia, and a chest X-ray was unremarkable. His kidney–ureter–bladder X-ray, which also included the abdomen, showed a high-density material within the distal area of the stomach.

Results of the initial laboratory tests are as follows.

Serum Chemistries	Results	Reference Interval
Sodium (mEq/L)	135	136–145
Potassium (mEq/L)	4.5	3.5–5.1
Chloride (mEq/L)	108	98–107
Carbon dioxide (mEq/L)	7	23–29
Anion gap (mEq/L)	20	6–10
Glucose (mg/dL)	162	74–100
Creatinine (mg/dL)	1.5	0.9–1.3
Urea nitrogen (mg/dL)	17	6–20
Calculated osmol (mOsm/Kg)	275	282–300
Ethanol (mg/dL)	<10	N/A
Acetaminophen (μg/mL)	<2.5	N/A
Salicylate (μg/mL)	<2.8	N/A
Urine Drug Abuse Screen
Opiates	Negative
Methadone	Negative
Amphetamines	Negative
Barbiturates	Negative
Benzodiazepines	Positive
Cocaine	Negative
Phencyclidine	Negative
Hematology Results
WBC(×10^9/L)	11	4.0–11.0
RBC(×10^12/L)	4.3	4.70–6.10
Hemoglobin (g/dL)	11.0	13.0–18.0
Hematocrit (%)	34.9	39–50
Platelets(×10^9/L)	110	140–440
Urinalysis
Color	Amber	Yellow
Appearance	Hazy	Clear
pH	6	5–6
Specific gravity	1.028	1.002 – 1.030
All other dipstick results	Negative
Microscopic analysis	Nothing abnormal

Issues and Questions to Consider

1. What additional clinical laboratory tests should the physician consider?

2. Are Phillip’s signs and symptoms consistent with any trace-metal poisoning?

3. What laboratory instrumentation is used to test for trace-metal content in biological samples?

The results of additional laboratory tests follow.

	Patient’s Results	RI/Cutoff Values
Serum arsenic concentration (μg/L)	<2.0	2–23
24hr urine arsenic concentration (μg/gμg/g creatinine)	9950	<100
Other Trace-Metal Whole-Blood Panel
Mercury (μg/L)	<1	1.0–59
Thallium (μg/L)	<1	<5
Lead (μg/dL)	<1	<25
Hair arsenic concentration (μg/g)	6.5	<1

Issues and Questions to Consider

1. Why is the serum arsenic concentration so low?

2. Why is the urine arsenic concentration so high?

3. What are some pharmacokinetic issues that may be relevant to Phillip?

4. Identify possible treatment modalities associated with arsenic poisoning.

Answer 1

1. Additional clinical laboratory tests to be considered by the physician other than the tests in the second table given include atomic absorption spectroscopy (AAS), inductively coupled plasma-optical emission spectroscopy (ICP-OES), and/or inductively coupled plasma-mass spectrometry (ICP-MS).

2. Phillip’s signs and symptoms are consistent with trace-metal (arsenic) poisoning. He presented to the ED with headaches, nausea, dizziness, and episodes of repetitive vomiting.

3.  Laboratory instrumentation used to test for trace-metal content in biological samples is spectroscope.

4. Serum arsenic concentration is so low because heavy metals like arsenic are rapidly cleared from the blood.

5. Urine arsenic concentration is so high because arsenic stays in urine. Approximately 70% of arsenic is present in urine.

6. Pharmacokinetic issues that may be relevant to Phillip: Arsenic’s toxicity is based on the solubility, valence state, and rate of absorption and elimination. Approximately 70% of arsenic is secreted in urine, of which 50% of excreted arsenic appears as dimethyl arsenic acid (DMA), and rest as monomethyl arsonic acid (MMA), with the remainder as inorganic.

7. Possible treatment modalities associated with arsenic poisoning: Blood transfusions, taking heart medication in cases where the heart starts failing, using mineral supplements that lower the risk of potentially fatal heart rhythm problems, observing kidney function, bowel irrigation, chelation therapy, hydration therapy etc., are the options.