Parenteral Exposure Research Articles

Anaphylaxis after treatment with an endodontic material containing polyethylene glycol

Polyethylene glycol (PEG) is sometimes included in temporary endodontic filling materials to modify viscosity. PEG is considered a low hazard chemical, but parenteral PEG exposure is associated with a risk of anaphylaxis. We report two cases of anaphylaxis after treatment with an endodontic temporary filling material containing PEG. One patient survived after hospital treatment, but the second case was fatal. Extensive investigations were needed to find the culprit. Allergic reactions to PEG are increasingly reported and have significant implications for the patient. Precautionary measures are discussed.

Safety assessment of protein A and derivation of a parenteral health-based exposure limit

Protein A (PA) is a bacterial cell wall component of Staphylococcus aureus whose function is to bind to Immunoglobulin G (IgG). Given its ability to bind IgG as well as its stability and resistance to harsh acidic and basic cleaning conditions, it is commonly used in the affinity chromotography purification of biotherapeutics. This use can result in levels of PA being present in a drug product and subsequent patient exposure. Interestingly, PA was previously evaluated in clinical trials as well as supporting nonclinical studies, resulting in a database that enables the derivation of a health-based exposure limit (HBEL). Given the widespread use of PA in the pharmaceutical industry, the IQ DruSafe Impurities Safety Working Group (WG) evaluated the available information with the purpose of establishing a harmonized parenteral HBEL for PA. Based on this thorough, collaborative evaluation of nonclinical and clinical data available for PA, a parenteral HBEL of 1.2 μg/kg/dose (60 μg/dose for a 50 kg individual) is expected to be health protective for patients when it is present as an impurity in a biotherapeutic.

Perinatal nicotine vaping exposure induces pro-myofibroblastic phenotype in rat bone marrow-derived mesenchymal stem cells

Perinatal nicotine exposure via tobacco smoking results in increased proclivity to chronic lung disease (CLD); however, the underlying molecular mechanisms remain incompletely understood. We previously demonstrated that in addition to nicotine’s direct effects on the developing lung, there are also adverse molecular alterations in bone marrow-derived mesenchymal stem cells (BMSCs), which are vital to lung injury repair. Whether perinatal nicotine exposure via electronic-cigarette (e-cig) vaping also adversely affects BMSCs is unknown. This is highly relevant due to marked increase in e-cig vaping including by pregnant women. Hypothesizing that perinatal nicotine exposure via e-cig vaping predisposes BMSCs to a pro-myofibroblastic phenotype, pregnant rat dams were exposed to fresh air (control), vehicle (e-cig without nicotine), or e-cig (e-cig with nicotine) daily during pregnancy and lactation. At postnatal day 21, offspring BMSCs were isolated and studied for cell proliferation, migration, wound healing response, and expression of key Wnt and PPARγ signaling intermediates (β-catenin, LEF-1, PPARγ, ADRP and C/EBPα) and myogenic markers (fibronectin, αSMA, calponin) proteins using immunoblotting. Compared to controls, perinatal e-cig exposure resulted in significant decrease in BMSC proliferation, migration, and wound healing response. The expression of key Wnt signaling intermediates (β-catenin, LEF-1) and myogenic markers (fibronectin, αSMA, calponin) increased significantly, while PPARγ signaling intermediates (PPARγ, ADRP, and C/EBPα) decreased significantly. Based on these data, we conclude that perinatally e-cig exposed BMSCs demonstrate pro-myofibroblastic phenotype and impaired injury-repair potential, indicating a potentially similar susceptibility to CLD following perinatal nicotine exposure via vaping as seen following parenteral perinatal nicotine exposure.

A case-control study of risk factors for incident hepatitis B virus infection in South African blood donors

ObjectivesHepatitis B virus (HBV) infection remains a global health problem. Risk factors for HBV infection are usually assessed in prevalent rather than incident infections. To identify demographic and behavioral risks associated with incident HBV among South African blood donors. MethodsA case-control study was performed between November 2014 and January 2018. Cases were blood donors testing positive for HBV DNA with or without hepatitis B surface antigen but negative for antibody to hepatitis B core antigen. Participants completed an audio computer-assisted structured interview on exposures during the previous 6 months. Sex-specific multivariable logistic regression yielded independent associations between risks and HBV infection. Results56 females and 37 males with incident HBV were compared to 438 female and 439 male controls, respectively. For females, risk factors were accepting money or goods for sex, using agents to prepare one's anus prior to anal sex, penetrating injury, non-Black race, and lower educational status. Men reporting homosexual or bisexual orientation or sex with other men, previous injury, referral for HBV testing, or lack of medical insurance were at increased risk. For both sexes, having more than two male sexual partners increased risk. ConclusionsSexual behaviors predominated over parenteral exposures as risks for incident HBV in both female and male blood donors.

Monoclonal antibody therapy protects nonhuman primates against mucosal exposure to Lassa virus

Lassa fever (LF) is an acute viral illness that causes thousands of deaths annually in West Africa. There are currently no Lassa virus (LASV) vaccines or antivirals approved for human use. Recently, we showed that combinations of broadly neutralizing human monoclonal antibodies (BNhuMAbs) known as Arevirumab-2 or Arevirumab-3 protected up to 100% of cynomolgus macaques against challenge with diverse lineages of LASV when treatment was initiated at advanced stages of disease. This previous work assessed efficacy against parenteral exposure. However, transmission of LASV to humans occurs primarily by mucosal exposure to virus shed from Mastomys rodents. Here, we describe the development of a lethal intranasal exposure macaque model of LF. This model is employed to show that Arevirumab cocktails rescue 100% of macaques from lethal LASV infection when treatment is initiated 8days after LASV exposure. Our work demonstrates BNhuMAbs have utility in treating LASV infection acquired through mucosal exposure.

Interplay between HIV and Human Pegivirus (HPgV) Load in Co-Infected Patients: Insights from Prevalence and Genotype Analysis.

Human pegivirus (HPgV) is transmitted through sexual or parenteral exposure and is common among patients receiving blood products. HPgV is associated with lower levels of human immunodeficiency virus (HIV) RNA and better survival among HIV-infected patients. This study aimed to investigate the prevalence of HPgV and determine its subtypes in HIV-infected individuals living in Istanbul, which has the highest rate of HIV infection in Türkiye. Total RNA extraction from plasma, cDNA synthesis, and nested PCR were performed for HPgV on plasma samples taken from 351 HIV-1-infected patients. The HPgV viral load was quantified on HPgV-positive samples. HPgV genotyping was performed by sequencing the corresponding amplicons. In the present study, the overall prevalence of HPgV RNA in HIV-infected patients was 27.3%. HPgV subtypes 1, 2a, and 2b were found, with subtype 2a being the most frequent (91.6%). Statistical analysis of HIV-1 viral load on HPgV viral load showed an opposing correlation between HIV-1 and HPgV loads. In conclusion, these data show that HPgV infection is common among HIV-positive individuals in Istanbul, Türkiye. Further comprehensive studies are needed to clarify both the cellular and molecular pathways of these two infections and to provide more information on the effect of HPgV on the course of the disease in HIV-infected individuals.

Oral stimulation for promoting oral feeding in preterm infants.

Oral stimulation for promoting oral feeding in preterm infants.

Elemental impurities determination in bromhexine hydrochloride injections

Elemental impurities in drug products have no therapeutic effect and may pose toxicological concerns, therefore it is urgent to assess the safety of elements especially in parenteral exposure drug. In the present work, a high throughput inductively coupled plasma mass spectrometry (ICP-MS) method was developed for the quantitative determination of 31 elemental impurities in bromhexine hydrochloride injections from 9 manufactures. The method was successfully validated for linearity, accuracy, precision, stability, the LOD and the LOQ according to the United States Pharmacopeia (USP) < 233 > . All the elemental impurities determined were below the permitted daily exposure (PDE) limits proposed by the International Council for Harmonisation (ICH). However, significant differences were found between different manufactures’ products for some elements, particularly for Al, As, B, Ba and Zn. Besides, discussions considering potential risks of elemental contamination were also presented.

Sodium glycerophosphate use in parenteral nutrition improves mineral metabolism in extremely low birth weight infants.

To evaluate the clinical effect of sodium glycerophosphate (NaGP) in parenteral nutrition solutions on mineral metabolism in extremely low birth weight (ELBW) infants. NaGP was introduced for use in place of potassium phosphate (K3PO4) in January 2018; this retrospective cohort study included 95 ELBW infants treated with K3PO4 between January 2015 and December 2017 and 77 infants treated with NaGP between August 2018 and January 2021. Mineral intake over the first 14days; changes in serum calcium, phosphorus, sodium, and alkaline phosphatase (ALP) levels over the first 1-3months; and the rates of electrolyte imbalance and clinical morbidity were compared. High-risk infants who had nil per os (NPO) status for >14days and prolonged parenteral nutrition exposure were further analyzed as a subgroup. The use of NaGP instead of K3PO4 significantly increased Ca and P intake, but intakes remained below the recommended range (Ca, 64-140mg/kg/day; P, 50-108mg/kg/day). Compared with levels in the K3PO4 group, the NaGP group had significantly higher serum Ca and P levels after day 14 and lower ALP levels after day 56. In the subgroup analysis, the NaGP group had significantly lower incidences of hypophosphatemia, hyponatremia, bronchopulmonary dysplasia, and ALP >500 IU/L. Although the administration of NaGP instead of K3PO4 in parenteral nutrition regimens still did not provide adequate Ca and P intake for ELBW infants, higher intake significantly improved serum Ca and P levels, especially in ELBW infants with prolonged parenteral nutrition exposure.

Anticonvulsant fatalities reported to the American Association of Poison Control Centers 2000 - 2019

BackgroundAnticonvulsants are frequently prescribed, and exposures are commonly reported to American Association of Poison Control Centers sites. The purpose of this study was to describe the epidemiology of fatalities associated with oral anticonvulsant use, including patient demographics, specific medications, and the circumstances surrounding the deaths. MethodsThis was a retrospective analysis of cases coded with oral anticonvulsants as a single substance and associated with a fatal outcome reported to the AAPCC National Poison Data System from 2000 to 2019. Polydrug ingestions and parenteral exposures were excluded. Patient characteristics, circumstances of the ingestion, specific medication, and chronicity of use were described. ResultsWe identified 126 cases that were classified as fatalities associated with single anticonvulsant use. The five most implicated anticonvulsants were carbamazepine, gabapentin, lamotrigine, phenytoin, and valproic acid. The majority (68.3%) of fatal cases were suicides. Phenytoin was implicated in eight (89%) adverse reactions and seven (70%) therapeutic errors. Valproic acid caused one (11.1%) adverse reaction and was associated with one (10%) therapeutic error. Three (75%) unintentional fatalities were caused by carbamazepine.The plurality (42.1%) of fatal ingestions occurred in acute-on-chronic use. An additional 40 (31.7%) were acute. Chronic use accounted for 15 (11.9%) of fatal exposures, including 5/10 of fatalities attributed to therapeutic error. The chronicity of medication use was unknown in 18 (14.3%) of fatal ingestions.Narrative summaries were available in 14 cases. Four of the patients presented to the emergency department with minimal symptoms. The other 10 had varying degrees of central nervous system (CNS) depression. Seizures were observed in six cases. Hyperammonemia was reported in seven of nine valproic acid ingestions. ConclusionsFatalities associated with isolated anticonvulsant use are uncommon and typically occur following intentional overdoses. Fatal adverse reactions and therapeutic errors are most associated with phenytoin use and disproportionately affect elderly patients.

Parenteral Exposure of Mice to Ricin Toxin Induces Fatal Hypoglycemia by Cytokine-Mediated Suppression of Hepatic Glucose-6-Phosphatase Expression.

Ricin toxin is an agent of biodefense concern and we have been developing countermeasures for ricin threats. In doing so, we sought biomarkers of ricin toxicosis and found that in mice parenteral injection of ricin toxin causes profound hypoglycemia, in the absence of other clinical laboratory abnormalities. We now seek to identify the mechanisms underlying this hypoglycemia. Within the first hours following injection, while still normoglycemic, lymphopenia and pro-inflammatory cytokine secretion were observed, particularly tumor necrosis factor (TNF)-α. The cytokine response evolved over the next day into a complex storm of both pro- and anti-inflammatory cytokines. Evaluation of pancreatic function and histology demonstrated marked islet hypertrophy involving predominantly β-cells, but only mildly elevated levels of insulin secretion, and diminished hepatic insulin signaling. Drops in blood glucose were observed even after destruction of β-cells with streptozotocin. In the liver, we observed a rapid and persistent decrease in the expression of glucose-6-phosphatase (G6Pase) RNA and protein levels, accompanied by a drop in glucose-6-phosphate and increase in glycogen. TNF-α has previously been reported to suppress G6Pase expression. In humans, a genetic deficiency of G6Pase results in glycogen storage disease, type-I (GSD-1), a hallmark of which is potentially fatal hypoglycemia.

Insights on 21 Years of HBV Surveillance in Blood Donors in France.

Hepatitis B virus (HBV) infection is the most frequent viral infection found in blood donors (BDs) in France. We analyzed the epidemiological and sero-molecular data on HBV infection gathered over the past two decades by the French haemovigilance surveillance network, blood screening laboratories, and the national reference center for transfusion infectious risks (NRC). Between 2000 and 2020, 6149 of the 58,160,984 donations (1.06/10,000) tested HBV positive, 98% of them from first-time blood donors (FTBDs). In addition, 2212 (0.0071%) of the 30,977,753 donations screened for HBV DNA tested DNA positive, of which 25 (1.1%) were positive only for this marker. HBV prevalence decreased by 2.8-fold and the residual risk for transfusion-transmitted HBV infection decreased 13-fold and was divided by 13. The major risk factor for HBV infection was the origin of donors (endemic country, 66.5%), followed by parenteral exposure (10.7%). In the whole HBV-positive BD population, genotype D was predominant (41.8%), followed by genotypes A (26.2%) and E (20.4%), reflecting the geographical origin of donors. The low and decreasing prevalence and incidence of HBV infection in French BDs, coupled with a screening strategy using three HBV markers (HBsAg, anti-HBc and DNA), ensures a high level of blood safety, further reinforced by the implementation of pathogen-reduction measures.

HIV-1 Diversity and Drug Resistance in Treatment-Naïve Children and Adolescents from Rio de Janeiro, Brazil.

The human immunodeficiency virus type 1 (HIV-1) can be transmitted via parenteral, sexual, or vertical exposure routes. The number of HIV-1 cases detected yearly in children and adolescents in Brazil did not decrease over the last decade, representing ~5% of total cases described in the country. In recent years, the HIV-1 diversity and the prevalence of transmitted drug resistance mutations (TDRM) are moving toward a marked increase. In this study, we retrospectively evaluated the diversity of HIV-1 subtypes and the TDRM prevalence in 135 treatment-naïve HIV-1 vertically infected children and adolescents born in between 1993 and 2012. These children were assessed in either 2001–2007 or 2008–2012 when they were 0 to 17 years old. The individuals assessed in 2001–2007 (n = 38) had median CD4+ T cell counts of 1218 cells/mm3 (IQR: 738–2.084) and median HIV-1 plasma viral load of 4.18 log10 copies/mL (IQR: 3.88–4.08). The individuals (n = 97) evaluated in 2008–2012 showed median CD4+ T cell counts of 898.5 cells/mm3 (IQR: 591.3–1.821) and median HIV-1 plasma viral load of 4.69 log10 copies/mL (IQR: 4.26–5.33). A steady decrease in the median CD4 T+ cell counts was observed with age progression, as expected. The majority HIV-1 pol sequences (87%) were classified as pure HIV-1 subtypes (77% subtype B, 9% subtype F1 and 1.5% subtype C), while 13% of sequences were classified as recombinants (CRF45_cpx, n = 4; CRF28/29_BF1, n = 2; CRF02_AG, n = 1; CRF40_BF1, n = 1, CRF99_BF1, n = 1, URF_BF1, n = 8). The overall prevalence of TDRM was 14% (19/135), conferring resistance to the nucleoside reverse transcriptase inhibitors (NRTI, 13/135–9.6%), non-nucleoside reverse transcriptase inhibitors (NNRTI, 8/135–5.9%), and protease inhibitors (PI, 2/135–1.5%). The main TDRM observed for NNRTI was the K103N (n = 8), while the mutations T215I/Y/D/E (n = 7) and M184V (n = 4) were the main TDRM for NRTI. Only two TDRM were observed for PI in one individual each (M46I and V82A). Most TDRM were found in the HIV-1 subtype B (84%) sequences. This study reveals an HIV-1 epidemic with high diversity and moderate prevalence of TDRM in the pediatric population of Rio de Janeiro, indicating the existence of possible problems in the clinical management of prophylactic therapy to prevent mother-to-child transmission and future treatment options for the affected children.

Seroprevalence of Hepatitis C Virus in High School Students of Bangladesh - A Single Centre Study

Introduction: Hepatitis C virus is an important pathogen due to its high prevalence and ability to cause serious complications like chronic hepatitis, cirrhosis, end stage liver disease and eventually liver cancer. Aim of this study was to Hepatitis C virus seroprevalence in the high school going children in Bangladesh.&#x0D; Materials and Method: It was a cross sectional study carried out in Ghior D.N. High School, Manikganj over 600 high school students within the period from April 2007 to April 2008. Two hundred students each from class VIII to X were selected. Informed written consent was taken from each students and their demographic and socioeconomic attributes, various potential parenteral exposures to blood and blood products were noted down in pre designed structured questionnaire. Venous blood of 3.0 ml was collected and was tested for anti HCV by commercial kit according to standard operating procedure. All positive cases were confirmed by ELISA method. Statistical data analysis was performed using SPSS 20.0 software. Students T test and chi-square test was done to test the significance of the factors of study in relation with the seroprevalence of anti-HCV antibodies. P&lt; 0.05 was considered as significant.&#x0D; Results: The mean age of the participants was 14.6±2.26 years. Of the 600 students, 289 (48%) were male and 311(52%) were female. It was not statistically significant (P=0.089). Among the 600 students, none tested positive for hepatitis C. Of them, 60 (10.0%) belonged to upper class, 222 (37.0%) to middle class and 318 (53.0%) to lower class. Total 34 students had previous history of jaundice and 288 had previous surgeries. Both the comparison between previous jaundice with no jaundice and previous surgeries with no surgery was not statistically significant (P=0.18, 0.089).&#x0D; Conclusion: Prevalence of Hepatitis C is 0% in high school students in this study. Further extensive nationwide study should be carried out to determine the real scenario.&#x0D; Sir Salimullah Med Coll J 2022; 30: 51-54

20-Year-Old Man With Elevated Liver Tests

20-Year-Old Man With Elevated Liver Tests

The prevalence of bloodborne infections (hepatitis B and C, human immunodeficiency virus) among pediatric patients with oncological and hematological diseases and immunodeficiencies

Patients with oncological and hematological diseases are at high risk of acquiring bloodborne infections due to multiple blood transfusions and frequent parenteral exposure. In order to evaluate the prevalence of bloodborne infections (i. e., hepatitis B, hepatitis C, and human immunodeficiency virus (HIV)), we analyzed data on the seroprevalence of these viruses in patients admitted to the D. Rogachev NMRCPHOI from 2014 to 2020. We also performed a comparative analysis between these data and the prevalence of these infections in the total child population in Russia. The study was approved by the Independent Ethics Committee and the Scientific Council of the D. Rogachev NMRCPHOI. Among patients admitted to the D. Rogachev NMRCPHOI, the mean seroprevalence was 1.7% for hepatitis C, 0.2% for hepatitis B, and 0.1% for HIV. The seroprevalence of hepatitis B and C among our patients was 6 and 50 times higher than the prevalence among Russian children and adolescents, respectively. The prevalence of HIV among patients treated at the D. Rogachev NMRCPHOI was 3 times higher than that among the child and adolescent population in Russia. In patients with oncological and immunological diseases, the detection of HBV DNA, HCV RNA, and Anti-HBc is considered clinically useful and plays an important role in the diagnosis of occult hepatitis infections which cannot be identified with routine diagnostic tests. Our study with pediatric patients with oncological, hematological, and immunological diseases highlights the problem of nosocomial transmission of bloodborne pathogens. HCV transmission in medical facilities is the most pressing issue that requires the implementation of healthcare programs aimed at preventing parenteral transmission and at ensuring the safety of donated blood.

Ace gene polymorphisms are ineffective on contrast induced nephropathy

Background: The renin–angiotensin system regulates the haemodynamics. ACE gene polymorphisms are known to influence serum angiotensin converting enzyme level. Contrast nephropathy develops after exposure to intravascular contrast media that influence vascular hemodynamics. ACE gene polymorpisms may have an enhancing role in contrast media related renal injury.The aim of the study: The aim of this study was to investigate the impact of ACE insertion/deletion (I/D) polymorphism in contrast-induced nephropathy (CIN) development.Methods: 194 patients with chronic kidney disease that were administered iodinated contrast media were examined. Patients were monitored for at least 7 days for CIN development after parenteral contrast exposure. Control and patient groups were divided in terms of CIN development status. Polymerase chain reaction was performed for the genotyping of the ACE gene polymorphism from DNAs that were isolated from peripheral blood of the patients.Results: 83 patients with CIN (34 women, 49 men) and 111 control patients without CIN (43 women, 68 men) were enrolled. Gender was not statistically different between the two groups (p = 0.75). The average age of the CIN group (71) was greater than that of the control group (68). No association was detected between ACE gene polymorphism (II, ID AND DD genotypes) and CIN in both patients and controls.Conclusion: ACE gene polymorphisms does not influence contrast induced nephropathy development.

Update on shedding and transmission routes of porcine haemotrophic mycoplasmas in naturally and experimentally infected pigs

Horizontal transmission of Mycoplasma suis via parenteral exposure during standard practices or through bites during fightings have been identified as key epidemiological routes. However, as knowledge gaps on other potential shedding and transmission routes exist, the present study combines both laboratory experiments and field surveys to gain new insights into the epidemiology of porcine haemotrophic mycoplasmas. Splenectomised pigs were orally inoculated with a M. suis field strain and investigated for clinical signs related to infectious anaemia of pigs (IAP) and the presence of M. suis in blood, urine and saliva samples by qPCR. All blood samples were negative for M. suis and animals did not show obvious clinical signs of IAP throughout the entire study period. Additionally, urine, nasal and saliva samples from sows of conventional piglet producing farms and semen samples from a boar stud revealed no detection of M. suis and ‘Candidatus Mycoplasma haemosuis’ by qPCR. Thus, the results indicate that blood-independent transmission routes might be of minor relevance under field conditions.

Changing epidemiology of liver disease in Asia: Dual infection of HBV and HCV.

Transmission of hepatitis B virus (HBV) and hepatitis C virus (HCV) is similar regarding the mode of transmission and related risk factors. Therefore, it is not rare to encounter dual HBV/HCV infection in populations at risk of parenteral exposure to hepatitis viruses. Besides, in HBV endemic countries before the era of global HBV vaccination, dual HBV/HCV infection was clinically significant likely because of HCV superinfection over pre-existing HBsAg carriage. Universal childhood HBV vaccination was implemented worldwide since 1992. Public education programs for prevention of new hepatitis viral infections have been actively promoted recently by World Health Organization. Apart from preventive measures, potent anti-HBV agents effective in the control of viral replication have been introduced gradually in the past three decades. Direct acting antiviral agents capable of curing HCV infection in more than 97% of patients with chronic hepatitis C have also been widely implemented in the past decade. These interventions will change the epidemiology of new HBV or HCV mono-infection and dual HBV/HCV infection. Understanding the evolution in the epidemiology of dual HBV/HCV infection is important for evaluation of current public health policy towards infectious disease control in different countries. The changing prevalence of dual HBV/HCV infection in certain Asia-Pacific countries will be re-visited based on endemicity of HBV or HCV, as well as in populations at risk of parenteral viral infection.

Defining baseline variability of serum tryptase levels improves accuracy in identifying anaphylaxis

Acute increases of ≥20%+ 2 ng/mL (20+ 2 rule) over basal serum tryptase (BST) is the recommended threshold supporting a clinical diagnosis of anaphylaxis. Prospective studies have demonstrated high sensitivity for this algorithm after parenteral exposure, but specificity has not been evaluated. We sought to define a serum tryptase change that distinguishes baseline variability from anaphylaxis on the basis of intraindividual variation in BST. Ninety-three total subjects with atopy (n= 62) or hereditary α-tryptasemia (HαT) (n= 31) and ≥2 BST measurements were identified. Sequential BST variability measurements were modeled and threshold ratios that optimized sensitivity and/or specificity determined. Models were tested in 22 individuals with physician-diagnosed anaphylaxis and validated in independent cohorts of individuals with HαT (n= 33), indolent systemic mastocytosis (ISM) (n= 52), and ISM+ HαT (n= 12). Mature tryptase levels were measured in HαT (n= 19) and ISM (n= 20). An online application was developed for clinical use. As a result of BST variability, 9.7% (9/93) of primary cohort patients, and 18% (6/33) of HαT, 30% (16/53) of ISM, and 25% (3/12) of ISM+ HαT patients from validation cohorts met the 20+ 2 rule despite absent immediate hypersensitivity symptoms; mature tryptase was noncontributory among individuals with HαT or ISM at baseline. Aratio of acute tryptase/BST exceeding 1.685 provided the optimized diagnostic rule for jointly maximizing sensitivity and specificity. Statistically significant improvement in specificity relative to the 20+ 2 rule was observed among individuals with elevated BST caused by HαT and ISM. Using an acute tryptase/BST ratio of 1.685 improves specificity of measured changes among individuals with HαT and ISM while maintaining high sensitivity for confirmation of anaphylaxis.