Life-threatening hyponatremia caused by vinblastine

Hyponatremia During Induction Therapy in Distinct Pediatric Oncological Cohorts: A Retrospective Study

Background

Hyponatremia is a well-known adverse event of repeated therapy with vincristine in oncological patients. However, to date, data in pediatric patients with malignant diseases other than acute lymphoblastic leukemia (ALL) are sparse or lacking.

Materials and Methods

A retrospective study of 98 pediatric patients was conducted to analyze the incidence of hyponatremia in a Caucasian cohort of newly diagnosed ALL. For comparison, we further examined five other pediatric oncological cohorts (Hodgkin’s disease, Ewing sarcoma, Wilms tumor, benign glioma of the CNS, Langerhans cell histiocytosis) that receive alkaloids in their induction regimes.

Results

We found a high incidence of hyponatremia (14.7%) in our ALL cohort with a trend toward male patients of elementary school age. None of the affected patients showed neurological symptoms. By comparison, patients from other malignancy groups did not show significant hyponatremia, regardless of their comparable therapy with alkaloids. We here show a noticeable coincidence of hyponatremia and hypertriglyceridemia in ALL patients, indicating a possible role of L-asparaginase-related hypertriglyceridemia in the development of severe hyponatremia in such patients.

Conclusion

We report a higher incidence of hyponatremia following vincristine therapy in Caucasian children with ALL than published before. This hyponatremia could not be demonstrated in other oncologic cohorts treated with alkaloids. L-Asparaginase-induced hypertriglyceridemia may play a role in the certainly multifactorial development of hyponatremia in childhood leukemia.

Anticancer Medications and Sodium Dysmetabolism

Therapeutic advances have revolutionised cancer treatment over the last two decades, but despite improved survival and outcomes, adverse effects to anticancer therapy such as dyselectrolytaemias do occur and need to be managed appropriately. This review explores essential aspects of sodium homeostasis in cancer with a focus on alterations arising from anticancer medications. Sodium and water balance are tightly regulated by close interplay of stimuli arising from hypothalamic osmoreceptors, arterial and atrial baroreceptors and the renal juxtaglomerular apparatus. This delicate balance can be disrupted by cancer itself, as well as the medications used to treat it. Some of the conventional chemotherapeutics, such as alkylating agents and platinum-based drugs, can cause hyponatraemia and, on rare occasions, hypernatraemia. Other conventional agents such as vinca alkaloids, as well as newer targeted cancer therapies including small molecule inhibitors and monoclonal antibodies, can cause hyponatraemia, usually as a result of inappropriate antidiuretic hormone secretion. Hyponatraemia can also sometimes occur secondarily to drug-induced hypocortisolism or salt-wasting syndromes. Another atypical but distinct mechanism for hyponatraemia is via pituitary dysfunction induced by immune checkpoint inhibitors. Hypernatraemia is uncommon and occasionally ensues as a result of drug-induced nephrogenic diabetes insipidus. Identification of the aetiology and appropriate management of these conditions, in addition to averting treatment-related problems, can be lifesaving in critical situations.

Tumor-related hyponatremia

Hyponatremia is an important and common electrolyte disorder in tumor patients and one that has been reported in association with a number of different primary diagnoses. The correct diagnosis of the pathophysiological basis for each patient is important because it significantly alters the treatment approach. In this article, we review the epidemiology and presentation of patients with hyponatremia, the pathophysiologic groups for the disorder with respect to sodium and water balance and the diagnostic measures for determining the correct pathophysiologic groups. We then present the various treatment options based on the pathophysiologic groups including a mathematical approach to the use of hypertonic saline in management. In cancer patients, hyponatremia is a serious comorbidity that requires particular attention as its treatment varies by pathophysiologic groups, and its consequences can have a deleterious effect on the patient's health.

Drug-induced syndrome of inappropriate antidiuretic hormone secretion. Causes, diagnosis and management

Hyponatraemia is common among the elderly, and may be caused by physiological changes, disease processes or drugs. About half of elderly patients with hyponatraemia have features typical of the syndrome of inappropriate antidiuretic hormone secretion (SIADH). It is important to establish whether drugs are the cause, as this is easily remediable. The clinical manifestations of SIADH are predominantly attributable to hyponatraemia and serum hypo-osmolality. The severity of the signs and symptoms depends on the degree of hyponatraemia and the rapidity with which the syndrome develops. Although a growing number of drugs have been reported to produce SIADH, most published reports concern vasopressin and its analogues, thiazide and thiazide-like diuretics, chlorpropamide, carbamazepine, antipsychotics, antidepressants and nonsteroidal anti-inflammatory drugs. Old age is a risk factor for SIADH following the use of many of these drugs. The use of these drugs in combination, excessive fluid intake and other underlying conditions that limit free water excretion increase the risk. Drug-induced SIADH usually resolves following cessation of the offending agent(s). Additional measures are required in patients with symptomatic hyponatraemia, including fluid restriction and intravenous sodium chloride and/or furosemide (frusemide) therapy. Careful monitoring is essential, with particular attention paid to the rate and extent of correction of the hyponatraemia.