Why Lab Tests Are Important When Taking Hypertension Medication

The Importance of Labs When Taking Hypertension Medications

Lab tests are important when taking blood pressure medications because they monitor for common side effects of the medications and ensure the medication is preventing complications from the hypertension. Damage caused by high blood pressure or related medications may often first appear in your bloodwork. 

Keep reading to learn more about why lab tests are an important part of monitoring and treatment while taking hypertension medications.

Why Do I Need Blood Tests for High Blood Pressure Medication? 

Depending on your age and symptoms, your doctor will do labs to see if there is a cause of your high blood pressure. Note that, as we age, the most common cause of hypertension is being overweight and leading a sedentary lifestyle. Blood tests are done to check for levels of electrolytes and other chemistry functions that may indicate the reason for your hypertension.

Why Is It Important to Get Labs Done While Taking High Blood Pressure Medication?

It is important to get labs done while taking high blood pressure medications to assess possible organ damage from high blood pressure or complications from the long-term use of blood pressure medications.

What Labs Are Ordered for Hypertension?

Blood and urine labs are ordered for hypertension. The most common blood labs ordered for hypertension include:

• Fasting blood glucose

• Complete blood count

• Lipid profile (total cholesterol and triglycerides)

• Creatinine, BUN (assesses kidney function)

• Electrolytes (sodium, potassium, calcium)

• Thyroid stimulating hormone (TSH)

Blood tests like electrolytes, blood urea nitrogen, and creatinine levels assess kidney function. Lipid blood tests detect high cholesterol, which can increase the risks of high blood pressure and heart disease. Other blood tests such as TSH check thyroid hormone levels which, when abnormal, can affect blood pressure. 

Urine labs are ordered for hypertension, which include a urine microalbumin/creatinine ratio to detect any early injury to your kidneys.

Labs for Checking Medication Side Effects

Labs are used to check medication side effects. Some medications used to treat blood pressure are called diuretics, which work by making your kidneys release more sodium and water into the urine. 

This decreases the amount of fluid circulating inside your body, thus, lowering blood pressure. However, diuretics can shift electrolytes and make levels abnormal. Labs to check for these types of medications include:

• Sodium

• Potassium

• Calcium

• Bicarbonate

Many medications used to treat hypertension are metabolized or directly affect the kidneys, which has a risk of producing kidney damage, over time. However, this risk is small in comparison to the damage that hypertension causes to the kidneys when it is uncontrolled. Labs for checking potential kidney damage from long-term blood pressure treatment use include:

• BUN (blood urea nitrogen)

• Creatinine 

• GFR (glomerular filtration rate)

• Albumin, carbon dioxide, chloride, phosphate, potassium, and sodium

Checking medication side effects is important and routine, so that any concerns do not become a problem.

Labs for Checking Complications of Hypertension

Labs are used to check for complications and conditions that are commonly associated with high blood pressure. Hypertension can cause organ damage resulting in kidney disease and heart disease. Diabetes and high cholesterol are conditions that are very commonly found in association with hypertension and for which you will be screened regularly.

Labs and tests that may be used to monitor organ damage and associated conditions are:

• Blood glucose (risk for diabetes)

• Blood cholesterol (Having high levels of cholesterol and triglycerides increases your risk for heart attack and high blood pressure. According to the American Heart Association, more than 60% of people with high blood pressure also have high cholesterol.)

• Eye exam (damage done to the eyes by hypertension)

• Urinalysis (detects kidney function and dysfunction)

• EKG (takes a picture of electrical activity of the heart and heart rhythms)

• Echocardiogram which is an ultrasound (provides a visual of the heart and neck vessels, pumping function, and other abnormalities)

Do You Need an EKG If You Have High Blood Pressure?

Getting a baseline EKG (electrocardiogram) is customary to evaluate your heart muscle and make sure it is healthy. EKGs are painless and noninvasive tests that record the electrical signals of your heart. EKGs give clues to how your heart is functioning.

Checking for any other cardiovascular risk factors can include bloodwork such as cholesterol and triglycerides.

How Long After Taking Blood Pressure Medicine Should I Check My Blood Pressure?

Medications taken by mouth take time to break down and absorb into the bloodstream. Once the medication has reached the bloodstream, the effects of the medication are seen. Different types of blood pressure medications peak in the bloodstream at different times. 

You will begin to see a difference in your blood pressure during the "onset of action" phase of each medication. The peak effect time is going to be the time at which the medication will be most effective. On average, you can check your blood pressure about 30 minutes to 1 hour after taking your blood pressure medication(s) and see the decline in your blood pressure, and then again during the peak time, which will show the best results the medication will attain.

Common blood pressure medications and their onset of action and peak times are as follows:

Talk to a Doctor About Labs for Hypertension Medications

Labs are used to diagnose, treat, and manage hypertension medications. Staying up to date on your bloodwork can reduce your risk of developing complications related to prolonged high blood pressure. Labs are a safe and easy way to keep up with your health. If you have hypertension or are behind on your bloodwork, book an appointment to speak with a PlushCare doctor today.

Sources

• Mayo Clinic. High blood pressure (hypertension). Accessed on March 1, 2022 from https://www.mayoclinic.org/diseases-conditions/high-blood-pressure/diagnosis-treatment/drc-20373417 

• Skidmore-Roth, L. Mosby’s 2020 Nursing Drug Reference. St. Louis, MO: Elsevier. Textbook.