Persistently high BP, elevated Gamma GT and ESR

I am a gentleman aged 41 years. My BMI (Body Mass Index) is at the border line skewed to under weight.  I was diagnosed wih stage two primary systemic hypertension and high colesterol over a year ago. During stress test (which had to be stopped prematurely) the BP rose to 210/110.  ECG results then showed normal results.  Colesterol responded to low fat diet, but for the BP, I am under constant medication.  2 months ago I went for annual check up, and the results read as "boder line ECG. Shows left atrial enlargement and probably early repolarisation pattern". ESR was elevated to 42mm/hr. Previously, elevated Gamma GT was recorded. Around the time of test (september 2008)  up to now, BP readings has been fluctuating from 170/120 to140/90.

I just got a report from Ultrasound performed today where they checked the kidneys, liver, spleen and pancreas - results are all normal.

Given that background, could there be some factors causing the pressure to go up(i.e.secondary HT?)  Is there a possibility that there are problems with the liver (causing elevated Gamma and ESR) which can not be visible under ultrasound?  What tests can be done to confirm this and how can the source for the ESR be found and treated (if treatable?)  Is the left atrial enlargement dangerous?  Is it manageable?

I have lots and lots of questions on my condition. Am worried that the ESR elevation could be indicative of cancerous cells, but this could just be my layman understanding.   Please help