Urinary bicarbonate and metabolic alkalosis during exacerbations in cystic fibrosis

Giulia Spoletini; Giles Fitch; Lindsey Gillgrass; Christine Etherington; Ian Clifton; Daniel G. Peckham

doi:10.1183/23120541.00669-2021

Tables

TABLE 1

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
P_aCO₂ mmHg^#	5.25 (4.88–5.73)	4.49 (4.26-4.68)	<0.001
P_aO₂, 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; P_aCO₂: arterial carbon dioxide tension; P_aO₂: arterial oxygen tension; HCO₃^–: bicarbonate; BE: base excess. ^#: data presented as median (25th–75th percentile).