Document Type : Original Article
Authors
- Lena Jafri 1
- Nadeem Ullah Khan 2
- Muhammad Akbar Baig 3
- Noman Ali 4
- Hafsa Majid 5
- Ayesha Habib Khan 6
1 Assistant Professor at Department of Pathology and Laboratory Medicine, Aga Khan University Hospital, Karachi, Pakistan
2 Associate Professor and Consultant, Department of Emergency Medicine, Aga Khan University Hospital, Karachi, Pakistan
3 Senior Instructor at Department of Emergency Medicine, Aga Khan University Hospital, Karachi, Pakistan
4 Resident year V, Department of Emergency Medicine, Aga Khan University Hospital, Karachi, Pakistan
5 Senior Instructor at Department of Pathology and Laboratory Medicine, Aga Khan University Hospital, Karachi, Pakistan
6 Associate Professor and Head at section of Chemical Pathology, Department of Pathology and Laboratory Medicine, Aga Khan University Hospital, Karachi, Pakistan
Abstract
Background:Lead toxicity continues to remain a concerning health problem for developing nations like Pakistan. Due to the lack of studies, we aim to highlight the clinical spectrum of lead poisoning in patients presenting to an urban-based tertiary care hospital in Pakistan.
Method:This is a retrospective review of patients admitted form January 2011 to December 2014 using a structured questionnaire for recording demographics, comorbidities, clinical findings, biochemical abnormalities, clinical findings and treatment provided. Patients were categorized as children (≤18yrs) and adults (>18yrs), further divided into three groups; desired blood lead levels (BLLs) [lead levels <2ug/dl in children and <10ug/dl in adults], high but non-toxic [children 2-10ug/dl, adults 10-70ug/dl] and toxic [children >10ug/dl, adults >70ug/dl].
Result: A total of 86 patients were included in the final analysis, majority (69.6%) of whom were adult males with median age of 35 yrs. Median (IQR) BLL was 6.3 ug/dl (12.8-2.7) in all age groups with BLL in children and adults of 4.2 ug/dl (3.1-5.7) and 6.5 ug/dl (2.6-14.7), respectively. 72% of the children had complaints related to the central nervous system with majority complaining of irritability. The gastrointestinal system was most commonly implicated in adults (93%) with most common complaint of abdominal pain. The commonest risk factor showing a positive correlation with BLLs was battery handling in adults [median (IQR) BLL 18.4ug/dl (8.35-36.1)] and pica eating in children with BLLs in high but non-toxic range [median (IQR) BLL 5.2ug/dl (2.7-5.7)]. The highest BLLs were observed to lie within the high but non-toxic range group in one adult herbal medicine user (54.4 ug/dl) and in children observed in the toxic range group (>10ug/dl) due to occupational battery work exposure and residence in a congested zone.
Conclusion:Lead toxicity continues to be hazardous due to unchecked environmental and occupational exposure. Increasing awareness is tantamount in order to find a solution.
Keywords
Introduction:
Lead is a cumulative toxic metal and is known for its toxicity since time immemorial (1). The major environmental sources of lead exposure include air, dust, soil, drinking water and food contaminated with lead (2). In developing nations like Pakistan, occupations that impose greater risk for lead poisoning include working in industries manufacturing lead-related products such as paints, water pipes, batteries, eye cosmetics, food cans, petroleum (added as an anti-knocking agent), oaring and mining (3-8).
Lead is not an essential element and serves no purpose in the body. The routes of exposure for inorganic lead are primarily through ingestion followed by inhalation (4). Once it is absorbed, lead is found in all tissues, but eventually 90% or more of the body burden is accumulated in the bone with a biological half-life from years to decades. Lead is excreted primarily in the urine (5). It causes pathophysiological effects through the interference of various enzymatic systems by binding to sulfhydryl groups found on enzymes resulting in extensive free radical damage of cell structures including the DNA and cell membranes. Lead can cause a reduction of immune function resulting in excessive inflammation (6, 7).
Blood lead level is the most reliable indicator of lead intoxication. In 1991, the Centers for Disease Control and Prevention (CDC) redefined the reference value of elevated blood lead levels (BLLs) from >25 µg/dl to >10 µg/dl (8). In spite of lead being one of the most prevalent toxins, only few studies have so far been conducted in Pakistan. However, the published data clearly indicate that blood lead levels of both general population as well as the exposed groups are much above the internationally acceptable limits (9-12).
Lead poisoning is a serious public health concern in Pakistan. Although the biochemical and hematological features of acute/sub-acute lead poisoning have been well studied (13), there is paucity of data regarding the clinical spectrum of lead poisoning relevant to our population. Therefore, the objective of this study is to highlight the toxicological syndrome of lead poisoning in patients presenting to an urban-based tertiary care hospital of Pakistan.
Methods:
A retrospective chart review was conducted on all cases admitted at the Aga Khan University Hospital (AKUH) with Blood Lead Levels (BLL) test being performed for suspected or confirmed lead poisoning from period of January 2011 to December 2014. AKUH is a 563-bedded tertiary care teaching hospital in Karachi, Pakistan. It serves more than 80,000 patients annually and has a dedicated drug and poison information center for toxicology-related consultations (14). Whole blood lead levels were performed by graphite tube atomizer, atomic absorption spectrometer 200 series AA (Agilent Technologies, California, US). Three-level quality control materials were run with each batch of samples. The laboratory participated in proficiency testing survey of College of American Pathologist twice a year with >80% performance when compared with the peer group. The study was reviewed by the Ethical Review Committee of AKUH and was granted exemption (3344-Pat-ERC-14).
Medical files of patients registered at AKUH were reviewed using a pre-structured questionnaire by a trained investigator to record the following information about patients;
- Socio demographics,
- Comorbidities (diabetes, hypertension, congestive heart failure, chronic obstructive pulmonary disease, chronic kidney disease),
- Clinical findings (General Physical; pallor, fatigue, muscle/bone/joint pain, weight loss, lead lines on gums, Cardiovascular systems; elevated blood pressure, Central nervous system; developmental delay, learning disabilities, mood disorder/Irritability, seizure, headache, memory loss, hearing loss, foot/wrist drop pain/tingling/numbness of extremities, Gastrointestinal system; anorexia, abdominal pain, constipation, reproductive system; premature delivery, infertility, miscarriage, Renal system; acute Kidney Injury),
- Risk factors (lead battery handlers, pica eating habit, ayurvedic medicine user, aluminum utensils user, petrol pump station worker, resident of a newly painted house, home in polluted zone, home undergoing renovation) and
- Treatment provided (hospitalized for it, Chelation therapy provided).
The data were transferred into an Excel database (Microsoft Corporation, Redmond, WA), cleaned, and analyzed with SPSS version 20. Patients were categorized as children (≤18yrs) and adults (>18yrs); they were further divided into 3 groups; desired BLLs (lead levels <2ug/dl in children and <10ug/dl in adults), high but non-toxic (children 2-10ug/dl, adults 10-70ug/dl) and toxic (children >10ug/dl, adults >70ug/dl).
Normality of data was assessed using Shapiro-Wilk test. Test of normality showed significant results, so median (IQR) was reported. Continuous variables were summarized as medians and interquartile ranges (IQR), while categorical variables are summarized as frequency and percentages. Mann–Whitney U test was done to assess the relationship between systems involved, risk factors and BLLs. A cutoff p-value of < 0.05 was accepted as the cutoff for statistical significance.
Results:
Out of 103 patients presented for clinical suspicion of lead toxicity, medical records of 86 patients were reviewed. While twenty-nine patients (33.7%) belong to pediatric age group aged ≤18yrs [median (IQR) age of 5yrs (3-8.5)], a majority of fifty-nine patients (69.6%) belonged to the adult age group aged >18 years [median (IQR) age of 35yrs (25-49)]. The commonest comorbid conditions identified were of hypertension (11.5%; n=10) followed by diabetes (7%; n=6). Twenty (23%) patients were admitted while only one patient was treated with chelation therapy. The median (IQR) BLL was in high but not toxic range of 6.3 ug/dl(2.7-12.8). The median BLL values in adults and pediatric groups are shown in further detail in Figure 1. Amongst the systems involved, signs and symptoms related to gastrointestinal (GIT) system (p value <0.01) and central nervous system (CNS) (p value <0.05) were significant and their respective association with the different BLL groups are shown in further detail in Table 1 & Figure 2.
In the pediatric age group (aged ≤18yrs), we established 89% (n=26) of children to have BLLs that exceeds the desired range, i.e. > or equal to 2 ug/dl. Only one child had a toxic value exceeding > 10 ug/dl. The most common risk factor identified in 80% of the pediatric age group was that of pica eating with a median (IQR) BLL in high but not toxic range of 5.3 ug/dl (2.7-5.7) followed by occupational battery work exposure and indwelling within a congested area noted in one pediatric case only with BLL lying in toxic range of > 10 ug/dl (Table 2 & Figure 3).