Determination of Brain Natriuretic Peptide as a diagnostic factor for Urgent Hypertension in Patients with Hypertension; a Prospective Study in Patients Referring to the Emergency Department of Adalatian Hospital in Mashhad

BNP increases in certain pathological conditions such as hypertension, renal failure, myocardial infarction, atrial fibrillation, chronic obstructive pulmonary disease (COPD), acute respiratory distress syndrome (ARDS), cirrhosis, etc. Some of them are among the clinical conditions pointing to hypertensive emergency and also its side effects. Therefore, in this study, we aimed to investigate the effeciency of this variable as a diagnostic variable in patients with emergency hypertension.

In this prospective study, 100 patients presenting to the emergency center of Adalatian Hospital, Mashhad, Iran, who had blood pressure equal to or greater than 180/110 mmHg at the time of triage and initial visit were included in the study. In order to evaluate damage to the target organs and the possible diagnosis of emergency hypertension, they were examined by an emergency medicine specialist or resident and the necessary tests were performed. For this purpose, serum levels of blood urea nitrogen (BUN), creatinine (Cr), and TPI/Immune thrombocytopenic purpura (ITP) were checked and a complete neurological examination was performed on patients to determine the presence of focal or generalized neurological defects or the presence of pathology (intracerebral hemorrhage (ICH), ischemia) on brain computed tomography (CT) scan. Patients' eyes were also examined for retinal vascular damage with an ophthalmoscope, and electrocardiogram (ECG) was also taken. Patients were divided into two groups based on the

emergency hypertension and non-emergency hypertension. Meaning, if the criteria for emergency hypertension (target organ damage) were met, they were placed in the end organ dysfunction (EOD) group or hypertensive emergency (HE) group, and otherwise, they were placed in the group without EOD or hypertensive urgency (HU) group. Data analysis was performed using SPSS version 16 and descriptive and inferential statistics tests.

There was no statistically significant difference between the two groups in terms of age and gender (P> 0.05). Based on the tests performed on samples taken from the patients, in the case group BNP level was 6144.81 ± 3052.42 pg/mL and in the control group it was 4835.42 ± 3135.02 pg/mL. The results of T test showed that there was no statistically significant difference between the two groups (P = 0.941). Based on calculations performed, at the cut-off point of 180, BNP can predict kidney damage with 100% sensitivity and 41% specificity. Although specificity and positive predictive value are not high at this cut-off point, but sensitivity and negative predictive value are acceptable, which makes it suitable for screening.

The results of our study showed that BNP test did not have high specificity or positive predictive value, but it had acceptable sensitivity and negative predictive value, which makes it suitable for screening. Therefore, this test can be used as a supplement to other examinations and cardiovascular and renal tests.