Abdominal pain is one of the main reasons for seeking medical care in emergency and gastrointestinal departments. Abdominal pain ranges from mild self-limiting conditions to life-threatening emergencies. It is believed that 20–40% of abdominal pain etiologies remain unknown at the time of discharge. Some patients receive unnecessary treatment, even including emergency exploratory laparotomy. The reasons for abdominal pain are mainly caused by abdominal organ diseases, but extra-abdominal diseases and systemic diseases can also cause pain; in particular, abdominal pain caused by systemic diseases is easy to ignore, such as chronic poisoning, diabetic ketoacidosis, and allergic purpura. The final correct diagnosis depends on a comprehensive analysis of a detailed medical history, comprehensive physical examination and auxiliary examination.
CLP has a long history of becoming a public health problem and is more commonly found in children than adults. The absorption of lead mainly occurs in the respiratory and digestive tracts [2]. Although the lead pollution has decreased, lead exposure shows obviously regional differences in China. Some reports of lead poisoning in some economically backward rural areas are mainly from traditional Chinese folk treatment [3]. In 2012, the United States Centers for Disease Control and Prevention increased the standard of blood lead for adults to 10 μg/dL and for children to 5 μg/dL [4]. The symptoms of CLP are nonspecific, symptoms of CLP are related to blood lead levels. Patients with mild CLP (blood lead 10 μg/dL) present common nonspecific symptoms that usually include discomfort, anorexia, abdominal pain and irritability. Extremely high blood lead levels (> 70 μg/dL) may cause cerebral edema, encephalopathy and confusion, drowsiness, coma or epilepsy, and even death [5]. The most important initial management for CLP patients is removal from the source of exposure. If blood lead levels exceed 45 μg/dl, chelation treatment is recommended. The available agents include DMSA, dimercaprol, ethylene diamine tetra-acetic acid (CaNa2EDTA), and D-penicillamine [6].
This patient’s abdominal pain was severe colic, but with only slight physical signs. The patient presented the kind of characteristics of abdominal pain caused by CLP. Lead is an electropositive metal with high affinity for sulfhydryl groups and thus inhibits sulfhydryl-dependent enzymes. In particular, lead also changes the vasomotor action of smooth muscle due to its effect on Ca-ATPase, which can cause abdominal pain [7]. The patient was moderately anemic, with normocytic anemia and elevated bilirubin, mainly indirect bilirubin, without evidence of hemorrhagic anemia and hematopoietic dysfunction, without supplementation of hematopoietic materials after chelation therapy, the patient’s Hb increased to normal levels. First, lead inhibits the major enzymes involved with heme synthesis of δ-aminolaevulinic acid dehydratase, coproporphyrinogen oxidase and ferrochelatase as well as pyrimidine 5′-nucleotidase, Second, lead can also be attached to the erythrocyte membrane to interfere with Na+-K+-ATP enzyme, and as a result, erythrocytes become easier to hemolyze. Finally, anemia occurs, and bilirubin levels increase [8]. The patient’s physical examination revealed the formation of Burton’s lines on the upper and lower gums; Burton’s lines are blue-purplish lines on the gums. They are caused by a reaction between circulating lead with sulfur ions released during oral bacterial activity, which deposits lead sulfide at the junction of the teeth and gums [9]. The normal features of CLP include abdominal pain, anemia with basophilic stippling of red cells, blue-black gum deposits, and a lead line on joint radiography [10]. This case reminds us that in the face of a patient with abdominal pain, we should not only consider the usual reasons for abdominal pains, but also carefully inquire about the patient’s medical history and consider some other rare etiologies, such as CLP.
In conclusion, CLP is not a common cause of adult abdominal pain, the diagnosis of CLP is often delayed, and the abdominal pain can more easily conceal the underlying illnesses, detailed history taking and physical examination are crucial in early diagnosis and treatment. This report indicates that CLP should be considered as a differential diagnosis in cases of unexplained abdominal pain when other common causes have been excluded. The diagnosis of CLP is easy once it is suspected, this study may provide more clinical experience for diagnosis of CLP.