Tests The goals with testing are to detect high blood pressure, confirm that it is persistent over time, determine whether it is being caused by an underlying medical condition that may be able to be resolved or controlled, evaluate the status of body organs, get a baseline of organ health prior to the start of drug therapies, and to monitor hypertension control and organ status over time.
Laboratory Tests
Laboratory testing is not diagnostic for hypertension, but tests are frequently ordered to detect conditions that may be causing and/or exacerbating high blood pressure and to evaluate and monitor organ function over time.
General tests that may be ordered include:
- Urinalysis - ordered to help assess kidney function
- Hematocrit – may be ordered as part of the Complete Blood Count (CBC) to evaluate the ratio of fluid to solids in the blood
- BUN (Blood Urea Nitrogen) and/or Creatinine – to detect and monitor kidney dysfunction or to monitor the effect of medications on the kidneys
- Potassium – may be ordered as part of the Electrolyte panel, which also includes sodium, chloride, and carbon dioxide (CO2); used to evaluate and monitor the balance of the body’s electrolytes; some high blood pressure medications can upset the balance by causing excessive sodium and potassium loss
- Fasting Glucose – ordered to determine if blood glucose levels are within healthy ranges
- Calcium – may be ordered to determine how much total calcium or ionized calcium is circulating in the blood; increased activity of the parathyroid glands, which produces an increase in serum calcium, is associated with hypertension
- TSH (Thyroid Stimulating Hormone) and T4 – may be ordered to detect and monitor thyroid dysfunction
- Lipid Profile – may be ordered to evaluate levels of total cholesterol, HDL cholesterol, LDL cholesterol and triglycerides
The Basic Metabolic Panel (BMP) includes several of the tests listed above, so it may be ordered instead of the individual tests.
Specific tests that may be ordered based on the patient’s medical history, physical findings, and routine laboratory test results to help detect, diagnose, and monitor conditions causing secondary hypertension include:
Non-Laboratory Tests
Blood pressure measurement
This is the primary tool for detecting and monitoring hypertension. Although it can now be evaluated with a variety of electronic devices, blood pressure is traditionally and most accurately measured with a stethoscope and a blood pressure cuff (a sphygmomanometer – which includes a cuff, a bulb, and a pressure dial that reads the pressure in millimeters of mercury (mm Hg)). (For more about the procedure, see “How is High Blood Pressure Diagnosed?” on the National Heart, Lung and Blood Institute (NHLBI) web site.)
The doctor may have the patient wear a device that monitors and records the blood pressure at regular intervals during the day to evaluate their blood pressure over time. This is especially helpful during the diagnostic process and can help rule out the high measurements that are sometimes present only when the patient is in the doctor’s office. (See “High Blood Pressure: Using an Ambulatory Blood Pressure Monitor” on familydoctor.org.)
All of these forms of blood pressure measurement are considered indirect. Very rarely, a direct measurement of blood pressure may be required. This can be obtained by inserting a catheter into an artery to measure the pressure inside the blood vessel.
As part of the diagnostic process and to help evaluate the status of vital organs, the doctor may order or perform one or more of the following:
- ECG (Electrocardiography) – to evaluate the heart rate and rhythm and look for evidence of heart damage
- Eye Exam – to look at the retina for changes in the blood vessels (retinopathy)
- Physical Exam – to help evaluate the kidneys, to look for abdominal tenderness, to listen for bruits (the sound of blood flowing through a narrowed artery), to examine the thyroid gland in the throat for any enlargement or signs of dysfunction, and to detect any other clinical signs as they present
- Imaging scans, such as X-ray or ultrasound of the kidneys or X-ray of the chest
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