A 22 year old female, found to have severe anaemia by her General Practitioner, presented at the Haematology Clinic for further investigative studies. A full blood count and haemoglobin electrophoresis (EPG) were performed .
The results were as follows:
The blood film was mildly microcytic and hypochromic. There was an occasional nucleated red cell present while many of the red cells showed coarse basophilic stippling.
The EPG results were as follows:
Hb EPG Cellulose Acetate (pH 8.6) No abnormal band detected.
|Hb A2:||2.6 %||2.0-3.5 %|
|Hb F:||<1.0 %||<1 %|
Hb H inclusions: not detected
No abnormality detected.
Iron studies were normal in this case.
A bone marrow aspirate was performed. The marrow was hypercellular with increased erythropoiesis and mild dyserythropoiesis. No abnormal sideroblasts were seen.
As coarse basophilic stippling in the red cells is a feature of lead poisoning, a lead level was performed. The lead was found to be 5.0 umol/L with a normal range of 0-0.5 umol/L. The level of mercury was also examined and found to be <1 nmol/L with a normal range of ≤50 nmol/L.
After questioning the patient in this case study it became evident that the patient had been taking a medication supplied to her by her Indian doctor. The medicine was in a powder form. A sample of this medication was sent for analysis which showed that the powder contained 12 % lead.
Patients with lead poisoning clinically present with abdominal colic and constipation, peripheral neuropathy and anaemia. The anaemia is invariably a hypochromic microcytic anaemia as the ingestion of lead interferes with haem synthesis. It does so by inhibiting several enzymes directly involved with haem synthesis. Pyrimidine 5′-nucleotidase is one such enzyme.
In its absence, pyrimidine nucleotides accumulate in the red cells, preventing iron from being incorporated into haem at a normal rate. This leads to a shortened red cell life span resulting in a mild haemolytic anaemia. The characteristic feature on the blood film in lead poisoning is coarse basophilic stippling in the red cells. The hypochromic microcytosis is not necessarily associated with iron deficiency.
The patient in this case study was treated with Meso-2-3-dimercaptosuccinic acid (DMSA) commonly known as succimer, a compound approved by the FDA in the 1960’s for the chelation or removal of heavy metals, particularly lead and mercury. She was initially given a three week course of succimer, 400 mg in the morning and 600 mg in the evening. Her haemoglobin began to rise while the level of lead began to fall. Two months later a similar course of succimer was administered. By the end of the second course the lead level was 0.8 umol/L, still significantly raised. The haemoglobin had returned to normal.
The Public Health Act (1991) states that a lead level of ≥0.72 umol/L must be notified and that repeat testing should occur after three months to assess the effectiveness of treatment.