Human metabolism produces ~ 1 mmol/kg/day of H+ and this is excreted in the urine in a number of buffered forms. Renal failure is accompanied by a fall in plasma bicarbonate, which may initially be compensated for by lowering pCO2 through an increased respiratory rate. However, eventually plasma pH will start to fall, with a detrimental effect on organ function. This may be treated with sodium bicarbonate (half correction = 0.15 x Wt. (kg) x Base deficit (mmol/l)). However, repeated use of sodium bicarbonate will lead to the development of hypernatraemia, preventing further administration. Uncontrolled acidosis is an indication for dialysis.
When correcting acidosis secondary to renal failure a potential problem is hypocalcaemia. Serum calcium levels may already be low and as plasma pH rises there is a fall in ionised calcium levels, which may become symptomatic.