the glomerular filtration estimative predicts the renal function rate and not if a individual have hipertension or not. In Brazil, we have guidelines for classification the hipertension, she us helps the predict hipertension in a population.
Link (Paper in Portuguese): http://publicacoes.cardiol.br/consenso/2010/Diretriz_hipertensao_associados.pdf
eGFR is an indirect measurement (index) of renal functions.You can’t use eGFR value to predict hypertension. The most commonly used formula is the “4-variable MDRD,” which estimates GFR using four variables: serum creatinine, age, ethnicity, and gender. It not depends on blood pressure.