Evaluation of Strontium Interference in Calcium Measurement Procedures and Content in Supplements as Measured by ICP-MS.

BACKGROUND: Bone health supplements containing strontium are available without prescription, however, the effects of strontium interference on clinical laboratory calcium measurement procedures are unknown. METHODS: To evaluate strontium interference on total calcium measurements, plasma pools with exogenously added strontium were measured by 3 total calcium measurement procedures. For ionized calcium measurements, whole blood pools prepared with exogenously added strontium were measured by 2 ionized calcium measurement procedures. An inductively coupled plasma mass spectrometry assay (ICP-MS) was validated for research measurements of strontium content in commercially available supplements. RESULTS: Exogenous strontium addition to plasma caused positive bias for total calcium measurements. Strontium concentrations of 1.0 mg/dL (0.114 mmol/L), 2.5 mg/dL (0.284 mmol/L), and 5.0 mg/Dl (0.568 mmol/L) resulted in mean biases of 1.9% to 3.5%, 4.9% to 9.0%, and 10.8% to 19.2%, respectively, for total calcium measurement procedures. Biases for ionized calcium measurements were less than 4.5% for a strontium concentration of 5.0 mg/dL (0.568 mmol/L). An in-house-developed ICP-MS assay for strontium in commercially available supplements exhibited within-laboratory and within-run coefficients of variation of less than 3%, and a linear response was obtained over the assay analytical measurement range of 10 to 100 000 ng/mL (0.0001 to 1.141 mmol/L). Strontium recovery for the ICP-MS assay was 97.1% to 105.3%. The largest amount of strontium measured in dietary supplements was 395 mg in a 1054 mg tablet. CONCLUSIONS: Some dietary supplements contain larger amounts of strontium than indicated on the product label. High concentrations of strontium may cause significant interference for total calcium measurement procedures, but ionized calcium measurement procedures are not significantly affected.

Negligible Nux Vomica: Homeopathic Nux Vomica remedies don't contain strychnine?

INTRODUCTION: The St. Ignatius bean of the Strychnos ignatii tree and Nux Vomica homeopathic products presumably could contain the toxic alkaloids strychnine and brucine. This study aimed to determine the amount of these toxic alkaloids in some commercially available Nux Vomica products and the St. Ignatius bean and to determine if overdose of these products could result in clinically significant toxicity. METHODS: Using ultra-performance liquid chromatography-tandem mass spectrometry, various formulations of Nux Vomica products and St. Ignatius beans were analyzed for strychnine, and brucine with detection limits set at 0.1 ng/g. RESULTS: None of the analyzed Nux Vomica products contained any detectable strychnine or brucine, while the expected strychnine dose from a St. Ignatius bean would be < 0.001 mg. CONCLUSIONS: Overall, our study reveals that the amount of strychnine in homeopathic Nux Vomica products or St. Ignatius beans are not likely to result in clinically significant strychnine toxicity.

Cases from NACCT acute and intensive care symposium: altered mental status, seizures, and rash in a fumigation company employee.

CONTEXT: Methyl bromide is a halogenated aliphatic hydrocarbon that exists as a colorless gas or a volatile liquid. Methyl bromide historically had been used in fire extinguishers but is more commonly used as a gas fumigant for soil-borne diseases and pests. Methyl bromide is being phased out due to concerns for ozone depletion but can still be found. It is readily absorbed through the lungs while dermal absorption can also occur. Signs and symptoms of severe exposures include headache, respiratory distress, pulmonary hemorrhage, and seizures. In large pulmonary exposures, death can occur as rapidly as 1 h usually from respiratory failure. Methyl bromide can penetrate clothing and protective equipment presenting challenges to first responders. There is a debate over the mechanism of toxicity of methyl bromide and the role of hemodialysis and chelation in treatment. CASE DETAILS: A 22-year-old female employee of a fumigation company contacted emergency medical services (EMS) after opening a tank of compressed methyl bromide in her car. She was initially combative and confused. She underwent two water dermal decontaminations and was transported to the nearest tertiary center. She rapidly progressed to obtundation with seizure-like activity and dysrhythmias. Despite the supportive care and resuscitative efforts, she died approximately 1 h after her call to EMS. DISCUSSION: Methyl bromide exposures can be fatal, and this case highlights the difficulty in managing these acutely poisoned patients. Questions for consideration after this case include time spent on decontamination, use of adjunctive anti-epileptic drugs, role of chelation therapy, and the role of hemodialysis in the treatment of methyl bromide poisoning.