Last data update: Jan 27, 2025. (Total: 48650 publications since 2009)
Records 1-6 (of 6 Records) |
Query Trace: Makhmudov A[original query] |
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Determination of iodine content in dairy products by inductively coupled plasma mass spectrometry
Vance KA , Makhmudov A , Shakirova G , Roenfanz H , Jones RL , Caldwell KL . At Spectrosc 2018 39 (3) 95-99 A probing study to establish a reliable and robust method for determining the iodine concentration using the ELAN DRC II ICP-MS was performed in combination with a sample digestion and filtration step. Dairy products from locally available sources were evaluated to help determine the possibility and need for further evaluations in relation to the U.S. population’s iodine intake. Prior to analysis, the samples were aliquoted and digested for 3 hours at 90+/-3 C. Dilution and filtration were performed, following the digestion. The sample extract was analyzed, and the results were confirmed with NIST SRM 1549a Whole Milk Powder. Further experimentation will need to be performed to optimize the method for projected sample concentration and throughput. |
LAMP: A CDC program to ensure the quality of blood-lead laboratory measurements
Caldwell KL , Cheng PY , Vance KA , Makhmudov A , Jarrett JM , Caudill SP , Ho DP , Jones RL . J Public Health Manag Pract 2019 25 S23-s30 CONTEXT: The Lead and Multielement Proficiency (LAMP) program is an external quality assurance program promoting high-quality blood-lead measurements. OBJECTIVES: To investigate the ability of US laboratories, participating in the Centers for Disease Control and Prevention (CDC) LAMP program to accurately measure blood-lead levels (BLL) 0.70 to 47.5 mug/dL using evaluation criteria of +/-2 mug/dL or 10%, whichever is greater. METHODS: The CDC distributes bovine blood specimens to participating laboratories 4 times per year. We evaluated participant performance over 5 challenges on samples with BLL between 0.70 and 47.5 mug/dL. The CDC sent 15 pooled samples (3 samples shipped in 5 rounds) to US laboratories. The LAMP laboratories used 3 primary technologies to analyze lead in blood: inductively coupled plasma mass spectrometry, graphite furnace atomic absorption spectroscopy, and LeadCare technologies based on anodic stripping voltammetry. Laboratories reported their BLL analytical results to the CDC. The LAMP uses these results to provide performance feedback to the laboratories. SETTING: The CDC sent blood samples to approximately 50 US laboratories for lead analysis. PARTICIPANTS: Of the approximately 200 laboratories enrolled in LAMP, 38 to 46 US laboratories provided data used in this report (January 2017 to March 2018). RESULTS: Laboratory precision ranged from 0.26 mug/dL for inductively coupled plasma mass spectrometry to 1.50 mug/dL for LeadCare instruments. All participating US LAMP laboratories reported accurate BLL for 89% of challenge samples, using the +/-2 mug/dL or 10% evaluation criteria. CONCLUSIONS: Laboratories participating in the CDC's LAMP program can accurately measure blood lead using the current Clinical Laboratory Improvement Amendments of 1988 guidance of +/-4 mug/dL or +/-10%, with a success rate of 96%. However, when we apply limits of +/-2 mug/dL or +/-10%, the success rate drops to 89%. When challenged with samples that have target values between 3 and 5 mug/dL, nearly 100% of reported results fall within +/-4 mug/dL, while 5% of the results fall outside of the acceptability criteria used by the CDC's LAMP program. As public health focuses on lower blood lead levels, laboratories must evaluate their ability to successfully meet these analytical challenges surrounding successfully measuring blood lead. In addition proposed CLIA guidelines (+/-2 mug/dL or 10%) would be achievable performance by a majority of US laboratories participating in the LAMP program. |
Measurement challenges at low blood lead levels
Caldwell KL , Cheng PY , Jarrett JM , Makhmudov A , Vance K , Ward CD , Jones RL , Mortensen ME . Pediatrics 2017 140 (2) In 2012, the Centers for Disease Control and Prevention (CDC) adopted its Advisory Committee on Childhood Lead Poisoning Prevention recommendation to use a population-based reference value to identify children and environments associated with lead hazards. The current reference value of 5 mug/dL is calculated as the 97.5th percentile of the distribution of blood lead levels (BLLs) in children 1 to 5 years old from 2007 to 2010 NHANES data. We calculated and updated selected percentiles, including the 97.5th percentile, by using NHANES 2011 to 2014 blood lead data and examined demographic characteristics of children whose blood lead was ≥90th percentile value. The 97.5th percentile BLL of 3.48 microg/dL highlighted analytical laboratory and clinical interpretation challenges of blood lead measurements ≤5 mug/dL. Review of 5 years of results for target blood lead values <11 microg/dL for US clinical laboratories participating in the CDC's voluntary Lead and Multi-Element Proficiency quality assurance program showed 40% unable to quantify and reported a nondetectable result at a target blood lead value of 1.48 microg/dL, compared with 5.5% at a target BLL of 4.60 microg/dL. We describe actions taken at the CDC's Environmental Health Laboratory in the National Center for Environmental Health, which measures blood lead for NHANES, to improve analytical accuracy and precision and to reduce external lead contamination during blood collection and analysis. |
Reply: Iodine content in milk alternatives
Vance K , Makhmudov A , Jones RL , Caldwell K . Thyroid 2017 Response to "Iodine in Milk Alternatives". |
Iodine status in pregnant women in the United States: National Children's Study and National Health and Nutrition Examination Survey
Caldwell K , Pan Y , Mortensen ME , Makhmudov A , Merrill L , Moye J . Thyroid 2013 23 (8) 927-37 BACKGROUND: This report presents iodine data from NHANES and from a sample of pregnant women in the National Children's Study (NCS) Vanguard Study. METHODS: UI was measured in a one third subsample of NHANES 2005-2006, and 2009-2010 participants and in all 2007-2008 participants age six years and older. These measurements are representative of the general U.S. population. UI was also measured in a convenience sample of 501 pregnant women enrolled in the NCS initial Vanguard Study from seven study sites across the U.S. RESULTS: NHANES median UI concentration in 2009-2010 (144 microg/L) was significantly lower than in 2007-2008 (164 microg/L). Non-Hispanic blacks had the lowest UI concentrations (131microg/L) compared to non-Hispanic whites or Hispanics (147 and 148 microg/L, respectively). The median for all pregnant women in NHANES 2005-2010 was less than adequate (129 microg/L), the third trimester women had UI concentrations that were adequate ( median UI 172 microg/L). Third trimester women participating in the NCS study similarly had an adequate level of iodine intake, with a median UI concentration of 167microg/L. Furthermore, NCS median UI concentrations varied by geographic location. CONCLUSIONS: Dairy, but not salt, seafood or grain consumption, was significantly positively associated with median UI concentration in women of childbearing age. Pregnant women in their third trimester in the NHANES 2005-2010 had adequate median UI concentrations, but pregnant women in NHANES who were in their first or second trimesters had median UI concentrations that were less than adequate. Non-Hispanic black pregnant women from both the NHANES 2005-20010 and the NCS consistently had lower UI median concentrations than non-Hispanic whites or Hispanics. |
Iodine status of the U.S. population, National Health and Nutrition Examination Survey, 2005-2006 and 2007-2008
Caldwell KL , Makhmudov A , Ely E , Jones RL , Wang RY . Thyroid 2011 21 (4) 419-27 BACKGROUND: This report presents urinary iodine (UI) concentrations for the general U.S. population during 2005-2006 and 2007-2008. These findings are the fourth and fifth assessments of the population since National Health and Nutrition Examination Survey (NHANES) III (1988-1994), when the median UI concentration for the population decreased from NHANES I (1971-1974). METHODS: During 2005-2006 and 2007-2008, approximately 5000 participants per year were selected to participate in NHANES. The participants were interviewed and examined. UI concentration was measured on a random one third subsample of 2649 participants, aged 6 years and older in 2005-2006, and in all participants in 2007-2008. These urine iodine concentrations are representative of the general U.S. population by age, sex, and race/ethnicity. RESULTS: (i) The median UI concentrations for the general U.S. population in 2005-2006 and 2007-2008 were 164 mug/L (95% confidence interval [CI] 154-174) and 164 mug/L (95% CI 154-173), respectively. Also, the proportions of the population with a UI concentration of <50 mug/L during these survey periods were 9.8% +/- 1.3% and 8.8% +/- 0.4%, respectively. The median UI concentration and prevalence of ≥200 mug/L appeared to be higher in children and persons ≥70 years than in other age groups. (ii) In both surveys, children aged 6-11 years had median UI concentrations of ≥200 mug/L, and about 5% of them had a UI concentration of <50 mug/L. (iii) All pregnant women (sample size 184) surveyed during 2005-2008 had a median UI concentration of 125 mug/L (95% CI 86-198), and 56.9% +/- 7.9% of this group had a UI concentration of <150 mug/L. UI concentrations were lower among non-Hispanic black survey participants than non-Hispanic white and Mexican-American participants. CONCLUSIONS: These findings affirm the stabilization of UI concentration and adequate iodine nutrition in the general U.S. population since 2000. However, certain groups likely do not achieve a sufficient dietary iodine intake according to the World Health Organization. The needs of these vulnerable groups and the inadequacy of their dietary iodine intake should be addressed in future efforts. |
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