Lab Preparation Instructions for Hypertension Workup
For your lab workup, you should fast for 8-12 hours before blood draw (water is allowed), and bring a first morning urine sample if possible. 1
Fasting Requirements
You must fast for 8-12 hours before your blood draw to ensure accurate measurement of:
- Fasting glucose - essential for detecting diabetes, which affects 15-20% of hypertensive patients and significantly increases cardiovascular risk 1, 2
- Lipid profile (cholesterol and triglycerides) - lipid disorders are present in approximately 30% of hypertensive patients 1
During the fasting period:
- Drink only water - no coffee, tea, juice, or other beverages 2
- Take your regular medications unless specifically instructed otherwise by your physician 1
- Continue your blood pressure medications as prescribed 1
Urine Sample Instructions
Collect a first morning midstream urine sample if you can bring it to the lab within 2 hours, or plan to provide a sample at the lab facility 1:
- The urine test will check for protein (albumin-to-creatinine ratio) to detect kidney damage 1, 2
- A dipstick urinalysis will also be performed 1
Medication Considerations
Do NOT stop your medications before the lab work unless your physician specifically instructs you to do so 1:
- Your blood pressure medications should be continued 1
- If you take diuretics ("water pills"), continue them as prescribed 1
- Certain medications can affect specific test results, but your physician will interpret results in the context of your current medications 3
Tests Being Ordered
Your lab workup will include 1, 2:
- Blood tests: Sodium, potassium, creatinine with estimated kidney function (eGFR), fasting glucose, and lipid profile
- Urine test: Urinalysis with albumin-to-creatinine ratio to assess for kidney damage
- Serum uric acid: Given your hyperuricemia, this will be monitored as elevated levels are associated with cardiovascular damage in 25% of hypertensive patients 1, 4
Timing and Scheduling
Schedule your lab appointment for early morning (7-9 AM if possible) 1:
- This allows you to fast overnight while sleeping, making it more convenient
- First morning urine samples are most concentrated and provide better diagnostic information 1
- You can eat immediately after your blood draw
Important Caveats
- Abnormal kidney function is found in approximately 6.7% of hypertensive patients without other conditions, but increases to 26.3% in those with multiple medical problems 5
- Electrolyte abnormalities (particularly low potassium) occur in about 9.8% of newly diagnosed hypertensive patients and may indicate specific causes of high blood pressure requiring different treatment 5
- These baseline tests detect major cardiovascular risk factors and organ damage that substantially influence your treatment strategy 2, 6