Kidney biomarker helps predict outcome among stroke patients

This study evaluated the impact of kidney biomarkers on predicting the outcome among critically ill stroke patients. 

Stroke is a sudden brain dysfunction caused by blood flow disturbances. It can be caused by a blood clot in the brain (ischemic stroke) or a burst blood vessel (hemorrhagic stroke). Both types of stroke result in a lack of oxygen and food reaching the brain tissue, causing cell death.

Biomarkers are naturally occurring body substances or measurements that are associated with a disease and often used for predicting the progression or outcome of a disease.

To date, it is not known whether renal (kidney) biomarkers can predict the outcome in critically ill stroke patients. This study looked at two kidney biomarkers: albuminuria and estimated glomerular filtration rate (eGFR). Albuminuria is a condition where albumin (a type of protein) is present in urine and indicates that the kidneys are damaged. eGFR is a way of estimating how well kidneys filter blood. Both measurements are used to test kidney function where increased albuminuria (macroalbuminuria) and decreased eGFR indicate poor kidney function.  

This study measured albuminuria and eGFR in 153 patients who had just suffered from a stroke. Patients were then followed-up 3 months and 1 year later to see if disability or death had occurred. The average age of the stroke patients was 68 years old. Albuminuria was categorized according to the amount of albuminuria in urine; normal (< 30 mg/g), microalbuminuria (30-299 mg/g) and macroalbuminuria (>300 mg/g). Low eGFR was divided into three groups; >60 ml/min/1.73 m², 45-59 ml/min/1.73 m² and <45 ml/min/1.73 m².

The study found that only macroalbuminuria was associated with poorer 3-month and 1-year outcomes after stroke among patients with hemorrhagic and ischemic stroke. However, there was no significant association between macroalbuminuria and ischemic strokes caused by large blood vessel clots or clots originating from the heart (cardio embolic stroke). 

Macroalbuminuria in critically ill stroke patients is associated with higher incidence of disability or death within 3-months and 1-year of having a stroke. 

Macroalbuminuria in critically ill stroke patients is associated with higher incidence of disability or death within 3-months and 1-year of having a stroke. 

It is not known whether patients suffered from kidney impairment previous to being admitted to hospital with stroke and therefore this could have complicated treatment, disability and survival. Furthermore, albuminuria and eGFR are highly likely to vary on a daily basis, yet this study only recorded each measurement once after stroke thereby may not accurately determine the true level of albuminuria or eGFR. 

If you are worried about the clinical outcome after the occurrence of a stroke, requesting a test for albuminuria may provide some guidance into the short and long-term outcomes.