Baseline Laboratory Testing Before Initiating Amlodipine for Hypertension
Before starting amlodipine therapy, order a comprehensive metabolic panel (including sodium, potassium, calcium, creatinine with eGFR, and fasting glucose), complete blood count, lipid profile, thyroid-stimulating hormone, urinalysis with urine albumin-to-creatinine ratio, and a 12-lead ECG. 1, 2
Essential Laboratory Tests
Metabolic Panel Components
- Serum creatinine with estimated glomerular filtration rate (eGFR) to assess baseline kidney function and detect chronic kidney disease 1, 2
- Serum sodium, potassium, and calcium to detect electrolyte abnormalities that may suggest secondary causes like primary aldosteronism 1, 2
- Fasting blood glucose to identify diabetes mellitus, which significantly increases cardiovascular risk and influences treatment thresholds 1, 2
Hematologic Testing
- Complete blood count including hemoglobin and hematocrit to detect anemia or other hematologic abnormalities 1, 2
Cardiovascular Risk Assessment
- Lipid profile (total cholesterol, LDL-cholesterol, HDL-cholesterol, and triglycerides) for cardiovascular risk stratification 1, 2
- Thyroid-stimulating hormone to detect hypothyroidism and hyperthyroidism, both remediable causes of hypertension 1, 2
Urine Testing
Critical Distinction in Albuminuria Screening
Use urine albumin-to-creatinine ratio (UACR) instead of urine dipstick alone, as UACR is more sensitive for detecting early kidney damage and cardiovascular risk. 1, 2, 3
- Standard dipstick urinalysis misses microalbuminuria, which is an early marker of end-organ damage from hypertension 1, 3
- UACR between 30-300 mg/g indicates moderately elevated albuminuria and heightened cardiovascular risk 1, 3
- Even low-grade albuminuria below traditional thresholds predicts cardiovascular events 3
- Detection of albuminuria may inform medication choices, as ACE inhibitors or ARBs provide treatment benefits in patients with increased albuminuria 1
Cardiac Testing
- 12-lead electrocardiogram to detect left ventricular hypertrophy, arrhythmias (including atrial fibrillation), and ischemic heart disease 1, 2, 4
Optional Tests Based on Clinical Context
When to Consider Additional Testing
- Echocardiography if ECG shows abnormalities, cardiac murmurs are detected, cardiac symptoms are present, or detection of left ventricular hypertrophy would influence treatment decisions 1, 4
- Uric acid as part of the initial evaluation, particularly in resistant hypertension 1, 2
- Hemoglobin A1c if fasting glucose is >100 mg/dL (5.6 mmol/L) to assess for diabetes 1
Special Considerations for Women of Childbearing Potential
While amlodipine itself is not contraindicated in pregnancy (unlike ACE inhibitors, ARBs, or spironolactone which cause fetal damage), baseline pregnancy testing should be considered in women of childbearing potential as part of comprehensive hypertension evaluation, particularly if combination therapy or medication changes are anticipated. 1
Clinical Pitfalls to Avoid
- Do not skip the ECG even in younger patients, as it is essential for detecting left ventricular hypertrophy and arrhythmias 1, 2, 4
- Do not use urine dipstick alone for albuminuria screening; always order UACR for more sensitive detection of early kidney damage 1, 2, 3
- Do not delay basic laboratory testing once hypertension is confirmed, even though repeated BP measurements are needed to confirm the diagnosis 2
- Monitor for secondary hypertension clues in the initial workup, particularly hypokalemia (suggesting primary aldosteronism) or elevated creatinine (suggesting renal disease) 1, 4
Monitoring After Amlodipine Initiation
Although not part of baseline testing, be aware that amlodipine does not significantly alter biochemical parameters during therapy. Studies show no significant changes in plasma electrolytes, renal function, or hematological parameters with amlodipine treatment, though mild increases in creatinine unrelated to kidney dysfunction have been noted. 5, 6, 7