There is no good evidence for what type of workup an asymptomatic hypertensive patient should get in the ED. An ECG is likely to show LVH, a cxr will be normal in most cases, and many patients will have some degree of proteinuria.
So, what is a safe and reasonable strategy to workup these patients?
Consider checking a serum creatinine. I say consider because even this recommendation isn't terribly evidence-based. Elevated creatinine may NOT indicate that a hypertensive emergency is present, but if the creatinine is elevated it might persuade you to choose a different antihypertensive agent (HCTZ won't lower BP effectively if the creatinine near 2.0, and many of us would be a little hesitant to start an ACE-I if the creatinine is elevated). Although there is one study that showed absence of proteinuria and hematuria was correlated with a normal serum creatinine, many patients with asymptomatic HTN will have proteinuria.
Repeat the BP several times. One study has shown that as many as 1/3 of patients with high BP in the ED do not have elevated BP when followed up as an outpatient. Many patients' BPs will spontaneously decline (regression to the mean).
In the asymptomatic patient a CXR and ECG will likely not help you manage a patient, so don't waste your time and the patient's money getting it.
American College of Emergency Physicians 2006 Guidelines on the evaluation of asymptomatic HTN.
