Sweat Testing now offered to Aid Diagnosis of Cystic Fibrosis

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The Department of Chemical Pathology, a joint UKZN-National Health Laboratory Service (NHLS) Department at Inkosi Albert Luthuli Central Hospital (IALCH) in Durban, is offering Sweat Test Analysis using the Gibson – Cooke method, a gold standard procedure for the diagnosis of Cystic Fibrosis (CF).

The Red Cross Hospital (RCH) in Cape Town and IALCH are the only two centres in South Africa offering this particular diagnostic test. Setting up the test in KwaZulu-Natal was made possible through the assistance and training provided by the staff from Chemical Pathology Department at RCH.

A sweat test is a method used to assess the concentration of chloride in the sweat produced by a patient after a special stimulation. Mr Martin Naidoo, one of the technicians who administers the sweat test on patients, describes the procedure as fairly simple for anybody who is referred for the test: ‘A chemical known as Pilocarpine which stimulates the sweat glands to produce sweat is applied to an area of a patient’s arm. Electrolyte solution is applied to another portion of the arm and electrodes are thereafter positioned on these two areas. A small electrical charge is then applied to the arm of the patient, who will feel only a mild tingling sensation.

‘This initiates the process of Pilocarpine iontophoresis which results in sweat production. This process lasts about five minutes.  Gauze is then used to gather the patients sweat and it is weighed and sealed to prevent evaporation during its transportation to the laboratory for analysis. The whole sweat collection process takes between 30 – 60 minutes.

‘Once delivered to the lab, sweat is extracted from the gauze and its chloride concentration is measured using an analyser. Due to defective chloride channels, individuals with cystic fibrosis have much higher sweat chloride levels than healthy people,’ said Naidoo.

Cystic Fibrosis is a genetic disorder which usually starts in the infancy or early childhood and due to a build up of a thick and sticky mucous affects the lungs, liver, pancreas and intestine.

‘Adults who have a history of chronic lung disease or malabsorption are also occasionally tested. Those affected by CF are prone to recurrent lung infections, diarrhoea, poor growth, infertility and weight gain, among young males. CF is caused by a mutation in the CF gene that is a code for a protein known as the Cystic Fibrosis Transmembrane Regulator (CFTR). It is this abnormal CFTR protein that leads to disruption in chloride channels.’

The Head of the Department of Chemical Pathology at IALCH, Dr Magdalena Turzyniecka, explains the importance of this test: ‘Cystic Fibrosis has been considered to be a fatal disease in childhood. However, with improvements in available medical treatments and better multidisciplinary management of the disease, patients can now live well into adulthood. Thus is it important that the disease is diagnosed very early in order to implement the appropriate treatments and thus delay disease progression and improve the patient’s quality of life.

Dr Turzyniecka is a respected Chemical Pathologist and Specialist Metabolic Physician, and is the Head of the Chemical Pathology Department of UKZN and the National Health Laboratory Services (NHLS). 

-         Zakia Jeewa