Diagnosis of essential hypertension in humans by the determination of plasma renal cortexin using enzyme-linked immunosorbent assay.

Background: More than 90% of all hypertensive persons are reported to have essential hypertension (EH), a particular form of elevated blood pressure, for which no diagnostic test is currently available. The level of plasma renal (R) cortexin (PRC), a hypotensive protein produced in the kidney cortex cells, was reported to be reduced from 218 nM in the plasma of normotensive persons (NP) to 0 nM in the plasma of patients with EH. The feasibility of using the determination of PRC by enzyme-linked immunosorbent assay (ELISA) as a diagnostic test for EH was investigated.

Methods: The PRC was determined by ELISA using electrophoretically pure cortexin as the antigen. A total of 344 persons (male and female) with EH, with or without diabetes mellitus (DM), and receiving or not receiving any anti-hypertensive and/or anti-diabetic medication at presentation, as well as an equal number of age- and gender-matched NP participated in the study.

Results: All persons with EH, with or without co-existing DM, were found to have 0 nM PRC, regardless of whether they were receiving anti-hypertensive and anti-diabetic drugs, including those who had been taking these medications over an extended period of time (3 months).

Conclusions: The determination of PRC as a marker protein by ELISA, a rapid method that can be carried out in any diagnostic laboratory, was shown to be suitable for the diagnosis of EH, even in those subjects who had co-existing DM and were receiving both anti-hypertensive and anti-diabetic medication.