Metabolic emergencies in the oncology patient

Abstract

Amongst the principal metabolic situations that can require emergency attention in the oncology patient we find: hypercalcaemia, hyponatraemia, tumoural lysis syndrome, lactic acidosis, hyperuricaemia, renal failure, hyperammonaemia, hypermpotasaemia, etc. Hypercalcaemia is the most frequent metabolic complication in oncology, appearing in 10-30% of these patients. It has two main mechanisms, tumoural lysis and humoural hypercalcaemia mediated by PTHrP (a protein related to parathormone). The principal factor for its diagnosis is suspicion, since some symptoms are non-specific and can be attributed to other causes such as somnolence, constipation, etc. Treatment will be based on intensity and is started with calciuretic measures with an intense hydration with physiological serum and on some occasions with furosemide. Anti-reabsorptive measures include calcitonin, bisphosphonates, mithramycin, gallium nitrate and on occasions corticoids. Bisphosphonates such as pamidronate and zoledronate seem to be highly useful in these cases. Hyponatraemia is classified depending on plasmatic osmorality; when this is low we find ourselves facing an authentic hyponatraemia that can develop with an extra-cellular volume that is high (cardiac insufficiency, cirrhosis, nephrotic syndrome and renal insufficiency), low (renal and extra-renal sodium losses) and normal (principally SIADH, related to a high elimination of sodium in the urine with high urinary osmolarity in spite of this being low in blood). Several types of tumour and different chemotherapy drugs can produce this SIADH. Treatment will vary according to the type and intensity, but in general this is based on hydric restriction and the replacement of the sodium deficit, either through physiological serum or through hypertonic saline serums depending on the case, and on occasions furosemide for the elimination of excess water.