Evaluation valency of sweat testing after Gibson and Cooke for diagnosis of cystic fibrosis in patients with down syndrome

Menschen mit Trisomie 21 weisen häufig eine Gedeihstörung und eine erhöhte Infektanfälligkeit auf, weswegen im klinischen Alltag nicht selten ein Schweißtest zum Ausschluss einer Mukoviszidose (CF) durchgeführt werden muss. In der Literatur gibt es Hinweise, dass bei Patienten mit Trisomie 21 eine erhöhte Schweißosmolalität vorliegt, was zu falsch positiven Schweißtestuntersuchungen führen könnte. Bisher gab es keine Studie darüber, ob die Chlorid(Cl)-Messung im Schweiß bei Patienten mit Trisomie 21 zum Ausschluss einer CF herangezogen werden kann. Diese Studie stellt nun die Schweißsekretionsrate, sowie die Chlorid-Konzentration in Schweißproben von Probanden mit Trisomie 21 der von Kontrollpersonen gegenüber.Recurrent airway infections are common in patients with Down’s syndrome (DS). Hence, ruling out Cystic Fibrosis (CF) in these patients is often required. In the past, the value of sweat testing–the gold standard to diagnose CF–has been questioned in DS as false positive results have been reported. However, these reports are based on measurements of sweat osmolality or sodium concentrations, not chloride concentrations. This study analyses sweat secretion rate and chloride concentration in sweat samples of patients with DS in comparison to healthy control

Is sweat testing for cystic fibrosis feasible in patients with down syndrome?

Background: Recurrent airway infections are common in patients with Down’s syndrome (DS). Hence, ruling out Cystic Fibrosis (CF) in these patients is often required. In the past, the value of sweat testing – the gold standard to diagnose CF – has been questioned in DS as false positive results have been reported. However, these reports are based on measurements of sweat osmolality or sodium concentrations, not chloride concentrations. This study analyses sweat secretion rate and chloride concentration in sweat samples of patients with DS in comparison to healthy controls. Methods: We assessed sweat samples in 16 patients with DS and 16 healthy controls regarding sweat secretion rate (SSR) and sweat chloride concentration. Results: All measured chloride concentrations were within the normal range. The chloride concentrations were slightly, but not significantly lower in patients with DS (15,54 mmol/l (±4,47)) compared to healthy controls (18,31 mmol/l (±10,12)). While no gender gap in chloride concentration could be found, chloride concentration increased with age in both groups. Insufficient sweat was collected in 2 females with DS (12.5% of the study group) but not in an individual of the control group. A significant lower sweat secretion rate was found in the DS group (27,6 μl/30 min (± 12,18)) compared to the control group (42,7 μl/30 min (± 21,22)). In a sub-analysis, female patients produced significantly less sweat (20,8 ± 10,6 μl/30 min) than male patients with DS (36,4 ± 7,8 μl/30 min), which accounts for the difference between patients and controls. Furthermore, while the sweating secretion rate increased with age in the control group, it did not do so in the DS group. Once again this was due to female patients with DS, who did not show a significant increase of sweat secretion rate with age. Conclusions: Sweat chloride concentrations were within the normal range in patients with DS and therefore seem to be a reliable tool for testing for CF in these patients. Interestingly, we found a reduced sweat secretion rate in the DS group. Whether the last one has a functional and clinical counterpart, possibly due to a disturbed thermoregulation in DS patients, requires further investigation