Unusual presentation of cancer-induced lactic acidosis.

Lactic acidosis is a common cause of metabolic acidosis with high anion gap and is a potentially lethal complication of a number of diseases. It develops as a result of an imbalance between lactate production and utilization. Malignancies are a relatively uncommon cause between lactate production and utilization. Malignancies are a relatively uncommon cause. 18 An 84 year old woman was admitted because of dizziness. She appeared cachetic and her blood pressure was 100/50mm Hg without orthosis. A chest X-ray showed a left hilar mass with bilateral mass lesions in the lower lung fields bilaterally shown on needle biopsy to be poorly differentiated squamous cell carcinoma. Liver function tests were normal. Serum sodium was 132mmol/l, chloride 91 mmol/l, potassium 4.8mmol/l and the total bicarbonate, 16mmol/l and serum creatinine, 1.1 mg/dl. Arterial Pco2 was 24.5mmHg and the pH was 7.39. A technetium liver scan was normal. On the fifth day, the patient was afebrile and in mild respiratory distress. The results of blood urea nitrogen and serum creatinine were unchanged, toxicology screen was negative, there was no ketonuria and the arterial pH was 7.13. The blood lactic acid level was 14mmol/l. The patient was treated with parenteral sodium bicarbonate. Two days later, the arterial pH was 7.34 and total bicarbonate 10.2mmol/l. The blood lactic acid level was 13.5mmol/l. Lactic acidosis persisted and she died on the fifteenth hospital day. None of the usual causes of lactic acidosis such as septicaemia, shock, hypoxaemia or advanced liver failure was noted in our patient. It appears that the squamous cell carcinoma of the lung may have been responsible for the lactic acidosis. Lactic acidosis is a well recognized problem in patients with hyperleucocytic leukaemias1' 5 and in lymphomas4 and reflects the high metabolic rate of the tumour cells and the associated tissue hypoxia due to hyperleucocytosis. In solid tumours, however, simultaneous liver involvement appears to be an important determinant causing impairment of lactic metabolism.2'3'6'7 The mechanism of lactic acidosis in solid tumours, however, is far from clear, particularly in those without massive liver involvement although speculation concerning the effects of tumour-related products exists.2 8 Furthermore, we did not observe any elevation of blood lactate levels after bicarbonate infusion as was previously reported.3