Lactic acidaemia

In Leigh s encephalopathy, pyruvate carboxylase is virtually absent from the liver [135, 136]. As a consequence, the concentration of pyruvic acid [137] in the blood rises (up to 5 mg per 100 ml) and this leads to lactic acidaemia [138] (30 mg per 100 ml or more), hypereJaninaemia (up to 12 mg per 100 ml) lactic aciduria and increased excretion of alanine [139], the three substances being interconvertible. 

Deficient activity of muscle cytochrome c oxidase has also been reported in a patient with a mitochondrial myopathy associated with chronic lactic acidaemia, growth failure and nerve deafness (Monnens etaL, 1975) and in a patient with subacute necrotizing encephalomyelopathy (Leigh s disease)... 

Hulsman, W.C. and Fernandes, J. (1971), A child with lactic acidaemia and fructose diphosphatase deficiency in the liver. Pediatrics, 5,633. 

Monnens, L., Willems, J., Kollee, L. and Veerkamp, J. (1976), Lactic acidaemia due to hyperventilation in a child with severe mental retardation. Dev. Med. Child Neurol, 18,232. 

Mayatepek E, Schulze A. Metabolic decompensation and lactic acidosis in propionic acidaemia complicated by thieunine deficiency. J Inherit Metab Dis. 1999 22(2) 189-90. 

The administration of bicarbonate is to be used with cautioa The indiscriminate use of bicarbonate is particularly dangerous in resuscitation of patients with metabolic acidosis as a concomitant of hypovolaemic shock lactic acid itself is innocuous and is readily removed by the liver as soon as the perfusion of the tissues is re-established. If administration of bicarbonate causes alkalosis and shifts the oxygen dissociation curve to the left, there is interference with oxygen unloading at the cellular level in tissues which are already hypoxic. Treatment of metabolic acidosis by bicarbonate therapy is reserved for situations in which partial correction of the pH is needed to restore cardiac function, which is depressed by acidaemia as described in Chapter 4. 

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