Glucose/Potassium Ratio, a Novel Biomarker for the Prognosis of Patients with Subarachnoid Hemorrhage: A Review

Subarachnoid hemorrhage (SAH) is a life-threatening cerebrovascular event with high mortality and long-term morbidity. While clinical grading scales such as Hunt and Hess or the World Federation of Neurological Surgeons (WFNS) score aid in prognosis, their accuracy implies a neurological assessment that can be confounded in sedated patients, highlighting the need for objective biomarkers. Biomarkers offer an alternative approach for risk stratification. This review examines the prognostic value of the glucose/potassium ratio (GPR) in patients with aneurysmal SAH and its potential integration into future predictive models. A literature review of retrospective studies assessing the association between GPR and clinical outcomes in SAH was conducted. Evidence on the pathophysiological basis of stress-induced hyperglycemia and hypokalemia in SAH is presented, along with findings from five key clinical studies evaluating GPR in relation to mortality, vasospasm, delayed cerebral ischemia, and functional outcomes. Elevated GPR levels were consistently associated with poor short- and long-term outcomes in SAH patients. Studies reported significant correlations between GPR and 30-day mortality, poor Glasgow Outcome Scale (GOS) scores, increased incidence of cerebral vasospasm, and higher rates of rebleeding. The optimal GPR cutoff for predicting adverse outcomes was greater than 37 mg/dL, with multivariate analyses confirming GPR as an independent prognostic factor. GPR is a promising, cost-effective biomarker that integrates two stress-response parameters (glucose and potassium), both of which are independently associated with SAH prognosis. Its incorporation into future predictive models may enhance early risk stratification and guide clinical decision-making. Further prospective studies are warranted to validate its utility and standardize its clinical application.