Baseline characteristics, and serum and urinary electrolyte data from the two cohorts
| Cases | Controls | p-value | |
| Subjects, n | 15 | 16 | |
| Age, years | 31 (26–35) | 45 (33–59) | 0.002 |
| Males | 10 (66.7) | 7 (43.8) | 0.2 |
| BMI, kg·m−2 | 22.5 (17.4–24.9) | 27.8 (23–32) | 0.007 |
| FEV1 % | 36 (27–45) | 61 (55–99) | <0.001 |
| Emergency hospital admission | 0 | 13 (81.3) | <0.001 |
| Diagnosis | <0.01 | ||
| CF | 15 (100) | ||
| F/F | 9 (60) | ||
| F/MF | 3 (20) | ||
| F/RF | 3 (20) | ||
| Asthma | 9 (56.25) | ||
| Non-CF bronchiectasis | 3 (18.75) | ||
| Pneumonia | 3 (18.75) | ||
| ILD | 1 (6.25) | ||
| Comorbidities | |||
| Cardiovascular | 1 (6.7) | 5 (31.3) | 0.083 |
| Liver disease | 10 (66.7) | 1 (6.3) | 0.002 |
| Diabetes | 4 (26.7) | 1 (6.3) | 0.061 |
| ABG | |||
| pH | 7.46 (7.41–7.49) | 7.43 (7.42–7.49) | 0.953 |
| PaCO2 mmHg# | 5.25 (4.88–5.73) | 4.49 (4.26-4.68) | <0.001 |
| PaO2, mmHg | 9.6 (9–10.2) | 11.29 (8.19–13.87) | 0.281 |
| HCO3−, mmol·L−1 | 27.8 (26.3–30) | 23.4 (22.9–24.5) | <0.001 |
| BE, mmol·L−1 | 3 (2–7) | −0.85 (−2.75–0.17) | <0.001 |
| Serum HCO3−, mmol·L−1 | 28 (25.5–28.5) | 24 (22.5–24) | 0.001 |
| Serum chloride, mmol·L−1 | 101 (97.5–104) | 105 (102.5–106.5) | 0.067 |
| Serum sodium, mmol·L−1 | 138 (137.5–140.5) | 141 (138.5–141.5) | 0.108 |
| Serum potassium, mmol·L−1 | 4.1 (3.9–4.3) | 4.0 (3.8–4.2) | 0.892 |
| Urea, mmol·L−1 | 4.2 (3.2–6.4) | 5.5 (3.25–5.6) | 1.0 |
| Creatinine, μmol·L−1 | 61 (45.5–91) | 58 (53–64) | 0.650 |
| Urinary pH (lab) | 6.0 (5.75–6.5) | 6.0 (5.25–6.87) | 0.918 |
| Urinary HCO3−, mmol·L−1 | 3.5 (1.22–5) | 2.5 (0–9.75) | 0.982 |
| Urinary chloride, mmol·L−1 | 133 (65.25–174.75) | 49.5 (37.5–117) | 0.070 |
| Urinary sodium, mmol·L−1 | 99 (65.75–157.75) | 51.5 (29–91) | 0.056 |
| Urinary creatinine, mmol·L−1 | 11 (5.27–12.25) | 10.7 (4.72–16.96) | 0.711 |
| Fractional excretion | |||
| Chloride, % | 0.65 (0.42–1.05) | 0.73 (0.21–1.08) | 0.713 |
| HCO3−, % | 0.094 (0.04–0.29) | 0.076 (0–1.08) | 0.974 |
| Sodium, % | 0.54 (0.33–0.7) | 0.57 (0.089–0.75) | 0.533 |
Data are presented as n (%) and median (interquartile range), unless otherwise stated. BMI: body mass index; FEV1: forced expiratory volume in 1 s; CF: cystic fibrosis; F/F: homozygous for the F508del-CFTR mutation; F/MF: heterozygous for the F508del-CFTR mutation and a minimal function CFTR mutation; F/RF: heterozygous for the F508del-CFTR mutation and a residual function CFTR mutation; ILD: interstitial lung disease; ABG: arterial blood gas; PaCO2: arterial carbon dioxide tension; PaO2: arterial oxygen tension; HCO3–: bicarbonate; BE: base excess. #: data presented as median (25th–75th percentile).