Original Article

Investigation of the Usability of Serum Phospholipase A2, Neutrophil/Lymphocyte Ratio, Red Cell Distribution Width and Mean Platelet Volume Levels in the Grading of Scorpion Envenomation


  • İrfan Aydın
  • Mehmet Kaan Poyraz
  • Kasım Turgut
  • Abdullah Algın
  • Nurettin Aktaş

Received Date: 21.05.2020 Accepted Date: 06.07.2020 Eurasian J Emerg Med 2022;21(1):8-13


This study aimed to compare the serum phospholipase A2, neutrophil/lymphocyte ratio (NLR), red cell distribution width (RDW), and mean platelet volume (MPV) levels of patients who presented to our emergency department due to scorpion stings and to determine a laboratory parameter that could assist in clinical grading.

Materials and Methods:

Sixty-three patients presenting to the emergency department due to scorpion stings and 33 volunteers presenting for other reasons between May and October 2018 were included in the study. The serum phospholipase A2, NRL, RDW and MPV levels of the patients were determined and compared with the control group.


In the evaluation performed in the patient group, the mean serum leukocyte and serum lymphocytes were higher and the RDW mean was statistically significantly lower compared to the control group, (p=0.001, 0.003, and 0.004, respectively). There was no significant difference between the patient and control groups in terms of the serum MPV, platelet and serum phospholipase levels (p>0.05). When the patients’ serum MPV values were compared according to their clinical grade, a statistically significant correlation was found (rho: - 0.432, p<0.001).


In scorpion stings, as the clinical grade progresses, the MPV rate decreases. Therefore, the MPV level can be used as an auxiliary parameter to show the severity of scorpion stings.

Keywords: Scorpion sting, phospholipase A2, mean platelet volumes


There are many types of scorpions worldwide, some of which can cause severe or deadly envenomation. Since ancient times, the existence and toxicity of scorpions have been known, but this species does not carry disease factors; however, in order to protect themselves, they can cause envenomation and death by stinging people and animals (1).

Scorpion stings can cause severe skin reactions, neurological and respiratory problems, and severe systemic manifestations that can lead to cardiovascular collapse. In terms of their geographical location in Turkey, scorpions are particularly common in Southeast Anatolia due to the climate and socio-economic structure. There are 1,500 subspecies of scorpions worldwide and 50 subspecies are toxic to humans. In South America, North Africa, and Middle East, the subspecies of Leiurusquinquestriatus, Androctonuscrassicauda and Buthusoccitonus are dangerous. Turkey is estimated to be home to 13 subspecies of scorpions. In East and Southeast Anatolia Regions of the country, A. crassicauda (Figure 1) and L. quinquestriatus (Figure 2) are relatively common and constitute the most causes of stings (2).

Scorpion venom is a water-soluble, antigenic and heterogeneous mixture. The venom is formed by the release of neurotoxin, cardiotoxin, nephrotoxin, hemolytic toxin, phosphodiesterase, phospholipase, hyaluronidase, glycosaminoglycan, histamine, serotonin, tryptophan, and cytokine at different concentrations. However, the strongest toxin is neurotoxin (3).

In this study, the serum phospholipase A2, neutrophil/lymphocyte ratio (NRL), red cell distribution width (RDW), and mean platelet volume (MPV) levels of patients presenting to the emergency department after scorpion stings were compared to a control group. Additionally, clinical grading was performed in the patient group, and by comparing the A2, NRL, RDW and MPV levels between the grades, the parameters that could determine the severity of envenomation was investigated.

Materials and Methods

This prospective case-control study was conducted in the emergency department of a tertiary hospital. Our emergency department serves approximately 25,000 patients monthly with two attending physicians and three general practitioners. The study began after the approval of the local ethics committee (number: 2017/9-26).

Sixty-three patients who presented to the emergency department due to scorpion stings and 33 volunteers presenting with other complaints between May and October 2018 were included in the study. The patients included in the study were graded according to their clinical features as follows: Grade 1, local pain and paresthesia; Grade 2, spread of local pain and paresthesia toward the proximal; Grade 3, central pain and paresthesia findings in addition to central nervous system findings (increased oral secretion, nystagmus, blurred vision, and rapid tongue movements); and Grade 4, in addition to central nervous system findings, other system findings (rhabdomyolysis, multiple organ failure, etc.) (4). The blood samples obtained from the patients were analyzed in terms of the serum white blood cell count (WBC) (normal range: 4.5-10x10³/uL), phospholipase A2 (normal range: 86.4-167.6 nmol/min/mL), NRL (normal range: 1.65), RDW (normal range: 11.6%-15.8%), and MPV normal range, 6.8-10.8 fL) and compared to the control group. All cases presenting to the emergency room were treated according to the standard protocol. Patients under the age of 18 years, pregnant women, and individuals who did not agree to participate in the study were excluded.

Laboratory Analysis

Blood samples were obtained by venipuncture from both groups and stored at -80 °C after centrifugation at 1,000 g for 20 min and separation. The serum levels of the PLA2 protein were analyzed using ELISA kits supplied by Shanghai Sunred Biological Technology Co. Ltd. (Shanghai, China) according to the manufacturer’s recommended protocol. Along with the serum PLA2 levels, selected clinical and sociodemographic variables, namely affected body region, number of antivenoms, electrocardiogram tracing analysis, WBC, NRL, RDW, and MPV were recorded and analyzed.

Statistical Analysis

SPSS v.15.0 for Windows was used for the statistical analysis. Descriptive statistics were expressed as number and percentages for categorical variables, and mean, standard deviation, minimum, maximum and median values for numerical variables. The comparison of two independent groups of numerical variables was performed using the Mann-Whitney U test since the data did not meet the normal distribution condition. The ratios in the groups were determined by the chi-square analysis. The relationship of the ranks in the groups were examined by linear-by-linear association, and the relationship between ordinal and numerical variables was examined by the Spearman correlation analysis. The alpha significance level was set as p<0.05.


The study included 63 patients, 27 males and 36 females, with a mean age of 43.71±18.63 years, and 33 controls, 12 males and 21 females, with a mean age of 41.06±16.07 years. There was no statistically significant difference between the patient and control groups in terms of age and gender (Table 1, p=0.560 and p=0.538, respectively).

When the patient group was classified according to the clinical grade of envenomation, it was determined that most of them were in Grade 1 and least were in Grade 4. Concerning antivenom use, only nine (14.3%) patients received an antivenom and most were advanced-grade. The right upper extremity was the most affected body area (Table 2).

The mean serum leukocyte and serum lymphocytes were statistically significantly higher and the RDW mean was statistically significantly lower in the patient group compared to the control group (p=0.001, p=0.003, and p=0.004, respectively). A statistically significant difference was also observed in the RDW levels of the patient and control groups (p=0.045). However, no significant difference was found between the two groups in terms of the serum MPV, platelet and serum phospholipase levels (Table 3, p>0.05).

In the patient group, the leukocyte, neutrophil, lymphocyte, NLR, phospholipase, D-dimer and RDW levels did not significantly differ according to the clinical grade (p>0.05) (Table 4). However, it was determined that the MPV level was significantly decreased as the grade progressed (rho: -0.432, p<0.001) (Table 5, Figure 3).


Scorpion envenomation, widely seen, especially in South-eastern Turkey, is one of the frequent reasons for emergency presentations (5). Following a scorpion sting, certain anti-inflammatory and pro-inflammatory cytokines and mediators are released by the host depending on the scorpion subspecies. These released mediators and cytokines determine the degree of inflammation that can lead to major clinical effects, such as cardiac dysfunction, pulmonary edema, and shock (6). The MPV reveals the presence of inflammatory load and disease activity in many diseases (7). In a study conducted with 76 cases of scorpion envenomation in 2014, Capan et al. (8) reported that the patient group had significantly higher WBC and platelet distribution width values and were significantly lower mean MPV values ​​compared to the healthy control group. In another study, Gokay et al. (9) evaluated 189 cases of scorpion stings and found that the serum MPV value was within normal limits and there was no difference between the patient groups according to clinical grades.

Song et al. (10) examined the impact of Buthusmartensii Karsch-type scorpion venom on rabbits and showed that it significantly inhibited platelet aggregation. They attributed this to the increase in the ratio of PGI2/TXA2, indicating an association with increased PGI2 concentration in plasma (10). In a study on mice with and without scorpion venom, Nasr et al. (11) found that the platelet parameters were generally unaffected in both groups, but the MPV levels were decreased over time in the mice that had been given the venom. Such a big decline in the MPV levels within four hours of the administration of the venom cannot be explained by the production of new and small platelets. However, scorpion venom is likely to have an anticoagulant effect on existing platelets. In our study, there was no significant difference between the serum MPV levels of the patient and control groups but a significant decrease was observed in the MPV level of the patients as their clinical grade increased. Therefore, further studies are needed to elucidate this mechanism.

Scorpion venom is a water-soluble, antigenic and heterogeneous mixture containing a large number of toxins and additional compounds, including various amounts of neurotoxin, cardiotoxin, nephrotoxin, hemolytic toxin, phosphodiesterase, phospholipase, hyaluronidase, glycosaminoglycan, histamine, serotonin, tryptophan, substances that increase cytokine release, and agglutinins. Any of these compounds can be dominant in the venom of scorpion species. Neuromuscular, neuroanatomic and local tissue effects are the most important clinical effects (12).

In our study, no significant difference was found in the serum phospholipase A2 level of the patients after a scorpion sting compared to that of the control group. In their 2019 study on Centruroidesedwardsii, which is the most common scorpion species in Costa Rica. Diaz et al. (13) found that the C. edwardsiivenom was rich in peptides, proteolytic and hyaluronidase enzymes but it did not have any phospholipase A2 and fibrinogenolytic activity. Similarly, in our study, this enzyme may not have been present in scorpion venom, or a sufficient amount of poison may not have been transferred to the host. To clarify this issue, there is a need for further studies to determine the venom content of scorpions in our region.

RDW is a simple and inexpensive parameter reflecting the degree of heterogeneity (anisocytosis) of erythrocyte volume and is routinely used for the differential diagnosis of anemia. Increased RDW has been reported in various diseases and disorders, such as cardiovascular disease, venous thromboembolism, cancer, diabetes, community-acquired pneumonia, chronic obstructive pulmonary disease, liver and kidney failure, and other acute or chronic conditions (14). In our study, the amount of RDW was determined to be lower in the patient group compared to the control group.

Study Limitations

This was a single-center study with a small number of patients. Additionally, only scorpion stings in our region were included in the study, and the species of scorpions that had stung the patients were not known. Therefore, the venom content of the scorpion species and how much venom the patients had been exposed to could not be determined. The blood samples were obtained from the patients only at the time of presentation, with no additional blood sample being taken during the follow-up. A study conducted in multiple centers to examine envenomation cases caused by different scorpion species can provide more comprehensive results.


We found that the serum leukocyte and lymphocyte levels were higher and the serum RDW level was lower in the patient group compared to the control group. Additionally, a significant relationship was observed between clinical grading and the serum MPV level. Therefore, it is concluded that the serum MPV level can be used as an auxiliary parameter in determining the severity of envenomation in patients presenting with a scorpion sting.


Ethics Committee Approval: This study was approved by the Adıyaman University Faculty of Medicine Clinical Research Ethics Committee with the date of 19.12.2017 and number 2017-9-26.

Informed Consent: Patient consent has been received.

Peer-review: Externally peer-reviewed.

Authorship Contributions

Concept: İ.A., Design: İ.A., Data Collection or Processing: İ.A., M.K.P., K.T., A.A., N.A., Analysis or Interpretation: İ.A., M.K.P., K.T., A.A., N.A., Literature Search: İ.A., Writing: İ.A.

Conflict of Interest: The authors declare that they have no conflict of interest.

Financial Disclosure: The authors declared that this study received no financial support.

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