Does bicarbonate of soda affect water balance when it is prescribed to treat people with kidney failure?

INTERVENTION: Oral sodium bicarbonate 1.5 g three times a day for 4 weeks versus placebo. Follow up is complete at the end of the 4‐week treatment period. CONDITION: Chronic kidney disease ; Urological and Genital Diseases ; Chronic kidney disease PRIMARY OUTCOME: Extracellular water and total body water measured by bromide space and deuterium dilution at 4 weeks. SECONDARY OUTCOME: The following will be assessed at 4 weeks: ; 1. Blood pressure; 2. Bio‐impedance measures of total body water (TBW) and extracellular fluid (ECF) INCLUSION CRITERIA: 1. Chronic kidney disease (CKD) (creatinine greater than 180 mcmol/l or glomerular filtration rate [GFR] less than 60 ml/min) 2. Aged over 18 years, male and female