You may be directed to seek medical care if blood pressure readings are elevated if done as part of a community health screening. Isolated elevated blood pressure readings do not necessarily make the diagnosis of hypertension.
http://www.emedicinehealth.com/high_blood_pressure/page4_em.htm
February 10, 2011. A hypertensive crisis occurs when blood pressure readings are 180/110 or higher. Unlike hypertension, which might slowly cause blood vessel and organ damage over a period of years, a hypertensive crisis can cause severe organ damage over a short period of time and is considered a medical emergency.
http://www.healthcommunities.com/high-blood-pressure/hypertensive-crisis-urgency-emergency.shtml
I'm not a doctor or nurse, but do know about blood pressure from my own experience. Mine is low. At times it's 90/54 other times 100/59, it does fluctuate. I looked into cardiovascular issues and blood pressure through a medical institute.
https://answers.yahoo.com/question/index?qid=20090813230535AAorb2P
A hypertensive (high blood pressure) crisis is when blood pressure rises quickly and severely. There are two types of hypertensive crises — both require immediate medical attention. If you get a blood pressure reading of 180/110 or greater, wait about five minutes and try again.
https://www.heart.org/HEARTORG/Conditions/HighBloodPressure/AboutHighBloodPressure/Hypertensive-Crisis_UCM_301782_Article.jsp
If your high blood pressure reading skyrockets or you experience symptoms, do not wait to seek medical attention—call 911 or ask to be driven to the nearest emergency room. A hypertensive crisis can be treated with a number of different oral or intravenous drugs that lower blood pressure.
http://www.healthcommunities.com/high-blood-pressure/hypertensive-crisis-urgency-emergency.shtml
When discussing blood pressure issues, the health care practitioner may ask questions about past medical history, family history, and medication use, including prescriptions, over-the-counter medications, herbal remedies, and food additives.
http://www.emedicinehealth.com/high_blood_pressure/page4_em.htm
No matter what medications your doctor prescribes to treat your high blood pressure, you'll need to make lifestyle changes to lower your blood pressure. Your doctor may recommend several lifestyle changes, including: Eating a healthier diet with less salt (the Dietary Approaches to Stop Hypertension, or DASH, diet)
http://www.mayoclinic.org/diseases-conditions/high-blood-pressure/basics/treatment/con-20019580
Many symptoms present gradually after years of poorly blood pressure control. Many times, the first knowledge of hypertension occurs when a patient complains of chest pain or has stroke-like symptoms. Should these occur, it is appropriate to call 911 immediately (if available) to activate emergency medical services and seek care.
http://www.emedicinehealth.com/high_blood_pressure/page4_em.htm
Know the two types of HBP crisis to watch for. A hypertensive (high blood pressure) crisis is when blood pressure rises quickly and severely. There are two types of hypertensive crises — both require immediate medical attention. Hypertensive Urgency. If you get a blood pressure reading of 180/110 or greater, wait about five minutes and try again.
https://www.heart.org/HEARTORG/Conditions/HighBloodPressure/AboutHighBloodPressure/Hypertensive-Crisis_UCM_301782_Article.jsp
A hypertensive emergency is a particularly severe form of high blood pressure. Blood pressure is at least 180/120 mm Hg, and there is evidence of progressive damage in one or more vital organs, often accompanied by a variety of symptoms. Malignant hypertension is one type of hypertensive emergency.
https://answers.yahoo.com/question/index?qid=20090813230535AAorb2P
what blood pressure needs medical attention
The blood pressure 180 by 110 or greater needs medical attention.  Blood pressure of 180/110 or greater needs medical attention.