Evaluation and management of hypernatremia in adults: clinical perspectives

Abstract

Hypernatremia is an occasionally encountered electrolyte disorder, which may lead to fatal consequences under improper management. Hypernatremia is a disorder of the homeostatic status regarding body water and sodium contents. This imbalance is the basis for the diagnostic approach to hypernatremia. We summarize the eight diagnostic steps of the traditional approach and introduce new biomarkers: exclude pseudohypernatremia, confirm glucose-corrected sodium concentrations, determine the extracellular volume status, measure urine sodium levels, measure urine volume and osmolality, check ongoing urinary electrolyte free water clearance, determine arginine vasopressin/copeptin levels, and assess other electrolyte disorders. Moreover, we suggest six steps to manage hypernatremia by replacing water deficits, ongoing water losses, and insensible water losses: identify underlying causes, distinguish between acute and chronic hypernatremia, determine the amount and rate of water administration, select the type of replacement solution, adjust the treatment schedule, and consider additional therapy for diabetes insipidus. Physicians may apply some of these steps to all patients with hypernatremia, and can also adapt the regimens for specific causes or situations.

Keywords: Correction; Evaluation; Hypernatremia; Sodium; Treatment.

Figure 1

Diagnostic approach to hypernatremia. sNa, serum sodium; ECF, extracellular fluid; TBW, total body water; TBNa⁺, total body sodium; U[Na⁺], urine sodium concentration; Uosm, urine osmolality; DI, diabetes insipidus; NaCl, sodium chloride.

Figure 2

Treatment of hypernatremia. DI, diabetes insipidus; NSAID, nonsteroidal anti-inflammatory drug.