Sweat, in cystic fibrosis

Gibson, L.E., and R.E. Cooke. 1959. A test for concentration of electrolytes in sweat in cystic fibrosis of the pancreas utilizing pilocarpine by iontophoresis. Pediatrics Evanston) 23 545. 

The first report of insulin iontophoresis was not related to diabetes management. It was an attempt to see if insulin could affect the saline content of sweat in cystic fibrosis patients (Shapiro et al, 1975). A decrease in sweat chloride was observed after insulin iontophoresis however, the role of the insulin, and whether insulin reached the circulatory system for systemic effect, was not clear. 

A number of clinical symptoms characterize cystic fibrosis. Predominant among these is the presence of excess sodium chloride in cystic fibrosis patient sweat. Indeed, measurement of chloride levels in sweat remains the major diagnostic indicator of this disease. Another characteristic is the production of an extremely viscous, custard-like mucus in various body glands/organs that severely compromises their function. Particularly affected are ... 

T. Bray, G. C. F. Clark, G. J. Moody and J. D. R. Thomas, A Perspective of Sodium and Chloride Ion-Selective Electrode Sweat Tests for Screening in Cystic Fibrosis, University of Wales, Cardiff (1975). 

The ease of application, the minimization of systemic side effects, and the increased drug penetration directly into the target region resulted in extensive clinical use of iontophoresis mainly in the transdermal field. This technique has been utilized for administration of local anesthetics [2-5], sweat chloride testing in cystic fibrosis patients by transcutaneous delivery of pilocarpine [6,7], administration of vidarabine to patients with herpes orolabialis [8], fluoride administration to patients with hypersensitive dentin [9,10], and gentamicin delivery for the management of burned ears [11],... 

Schulz IJ. Micropuncture studies of the sweat formation in cystic fibrosis patients. J Clin Invest 1969 48 1470-7. 

Although chloride is the principal anion in blood fluids, there are just a few instances of chloride ion-selective electrodes having been used for such assays [156—158] but the most important role of this electrode is for screening sweat chloride levels in cystic fibrosis diagnosis [159]. 

Ion-selective electrodes. These have particularly useful applications in the determination of sWeat chloride in cystic fibrosis see sweat test). 

In cystic fibrosis, the concentration of sodium and chloride in saliva may be raised in a similar manner to the sweat electrolytes. However, this is an inconsistent finding and the results are not considered as reliable as sweat electrolytes. 

Specific ion electrodes, similar in design to the glass electrode, have been developed to analyze for a variety of cations and anions. One of the first to be used extensively was a fluoride ion electrode that is sensitive to F- at concentrations as low as 0.1 part per million and hence is ideal for monitoring fluoridated water supplies. An electrode that is specific for Cl- ions is used to diagnose cystic fibrosis. Attached directly to the skin, it detects the abnormally high concentrations of sodium chloride in sweat that are a characteristic symptom of this disorder. Diagnoses that used to require an hour or more can now be carried out in a few minutes as a result, large numbers of children can be screened rapidly and routinely. 

Cystic fibrosis (CF) is a recessive genetic disorder prevalent among whites in North America and certain parts of northern Europe. It is characterized by chronic bacterial infections of the airways and sinuses, fat maldigestion due to pancreatic exocrine insufficiency, infertility in males due to abnormal development of the vas deferens, and elevated levels of chloride in sweat (> 60 mmol/L). 

In addition to blood, certain types of specimens are submitted to the Pediatric laboratory which would not be commonly seen elsewhere. An example of this is sweat for analysis of chloride. The process of obtaining the sweat by iontophoresis usually falls to the personnel of the Laboratory of Neonatology (17). Stool for analysis of lipids and trypsin is more commonly submitted to the Laboratory of Neonatology than to the laboratory which services the adult population. The reason for this is that one is screening for certain intestinal diseases characteristic of infants and newborns which are rare in adults. Such conditions would be celiac disease, cystic fibrosis and others. 

Cystic fibrosis (CF) is a hereditary disease of abnormal fluid secretion. It affects cells of the exocrine glands, such as intestine, sweat glands, pancreas, reproductive tract, and especially the respiratory tract. The disease affects about 1 in 2500 infants of the Caucasian population to varying degrees of seriousness. Patients produce thickened mucus that is difficult to get out of the airway. This leads to chronic lung infection, which progressively destroys pulmonary function. 

Chloride ion-selective electrodes The most important region of application is the determination of chlorides in waters, including sea water (for a review, see [167]), in serum [110,112,371] (review in [167]) and in soil [151,219,341], The determination of chloride ions in sweat made screening for cystic fibrosis possible in new-born babies (review, [45,55a, 262]). Br , I and S " interfere in the determination of chlorides in phosphate rocks [81]. Sulphite can be determined directly using an electrode with an Hgj CI2 - HgS membrane [398] on the basis of the reaction... 

Children with cystic fibrosis lose excessive amounts of salt in perspiration and become dehydrated readily. A salty taste of the skin and an elevated chloride concentration of sweat are traditional diagnostic symptoms.3 More serious problems arise from progressive respiratory failure and inadequate pancreatic secretion. Lung infections with Pseudomonas aeruginosa are the major cause of death. The CFTR gene is expressed in many tissues, especially those of the mucous membranes. 

An important condition to be fulfilled in order to use the method for detection of sweat formation and its composition is that the electrodes are elec-trolytically in contact with each other. This is not a strict condition for urine detection and as an early-warning system for diabetes, because in these applications a qualitative detection is enough, and therefore one can start with dry electrodes. For diagnosis of cystic fibrosis, this is not possible because here a quantitative detection of salt concentration is expected. Therefore, one needs to start from a system with electrodes that are elec-trolytically in contact with each other right from the start of the experiment. For this purpose, water is immobilised in high-density cotton in which the conductive stainless-steel yarn electrodes are implemented. 

For the detection of cystic fibrosis, which is a quantitative analysis, the situation is different because such an analysis is performed only in the hospital environment. This requires that the conditions to execute such a test with the sensor system can be chosen and controlled in such a way that possible interference is avoided. In addition, for cystic fibrosis detection, the analyst is interested in the electrolyte concentration of the sweat, regardless of how this sweat formation was obtained (high temperature, exercise), with the implication that the sources of interference are much less for cystic fibrosis detection than was the case for the detection of low sugar level in the blood. The complication in this type of analysis is that it is not enough to... 

Resistance measured between two yarn electrodes implemented in an electrochemical cell positioned at the leg of a human body as a function of time. Sweat formation rate (1) for normal people under strict conditions and (2) for cystic fibrosis patient. 

Carmen is a pale 20-year-old lady. Like many cystic fibrosis patients, she was diagnosed when she was a baby her problem was suspected when she suffered repeated respiratory infections and failed to gain weight as expected. Patients with cystic fibrosis secrete a high concentration of NaCl in their sweat and this forms the basis of an early diagnostic test for the condition. 

Sweat glands have sympathetic cholinergic innervation. Patients with cystic fibrosis secrete a large amount of salt in their sweat and this forms the basis of a diagnostic test for the condition. 

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