What initial laboratory tests should be ordered for a 33-year-old patient with uncontrolled hypertension (HTN)?

Laboratory Tests for Uncontrolled Hypertension in a 33-Year-Old Patient

For a 33-year-old patient with uncontrolled hypertension, you should order basic laboratory tests including fasting blood glucose, complete blood count, lipid profile, serum creatinine with eGFR, serum electrolytes (sodium, potassium, calcium), thyroid-stimulating hormone, urinalysis, and an electrocardiogram. 1

Initial Laboratory Workup

Essential Tests (Order These First)

• Fasting blood glucose - To screen for diabetes, which is present in 15-20% of hypertensive patients
• Complete blood count - To assess for anemia or polycythemia
• Lipid profile - To evaluate cardiovascular risk factors
• Serum creatinine with eGFR - To assess kidney function and screen for chronic kidney disease
• Serum electrolytes (sodium, potassium, calcium) - To detect electrolyte imbalances that may indicate secondary causes
• Thyroid-stimulating hormone - To rule out thyroid dysfunction
• Urinalysis - To screen for kidney disease, particularly albuminuria
• 12-lead electrocardiogram - To assess for left ventricular hypertrophy or other cardiac abnormalities

Additional Tests to Consider

For a young patient (33 years) with uncontrolled hypertension, consider these additional tests to rule out secondary causes:

• Urine albumin-to-creatinine ratio - To detect early kidney damage 1
• Serum uric acid - Hyperuricemia is common (25%) in hypertensive patients 1
• Liver function tests - To assess for liver abnormalities 1

Rationale for Testing in Young Patients with Uncontrolled HTN

The young age (33 years) of this patient with uncontrolled hypertension raises suspicion for possible secondary causes. Secondary hypertension should be considered when:

1. Age of onset is younger than 30 years
2. Hypertension is severe or resistant to treatment
3. There is an absence of family history of hypertension 1, 2

When to Consider Additional Testing for Secondary Causes

If the basic laboratory tests reveal abnormalities or the patient has any of these findings, consider specialized testing for specific secondary causes:

• Low potassium → Consider primary aldosteronism (aldosterone-renin ratio)
• Elevated creatinine or abnormal urinalysis → Consider renal artery imaging
• Abnormal thyroid function → Further thyroid evaluation
• History of snoring/daytime sleepiness → Sleep study for obstructive sleep apnea
• Episodic symptoms (palpitations, sweating, headaches) → Consider pheochromocytoma workup 1

Follow-up Recommendations

• If moderate-to-severe chronic kidney disease is diagnosed (eGFR <60 mL/min/1.73 m² or albuminuria ≥30 mg/g), repeat measurements of serum creatinine, eGFR, and urine albumin-to-creatinine ratio at least annually 1
• Consider echocardiography if the ECG shows abnormalities or if there are cardiac symptoms 1

Common Pitfalls to Avoid

1. Don't miss secondary causes in young patients - The prevalence of secondary hypertension is higher in younger patients
2. Don't overlook isolated systolic hypertension - This pattern is common even in untreated or uncontrolled hypertension 3
3. Don't assume medication non-adherence without investigation - Always rule out secondary causes in difficult-to-control cases

By following this systematic approach to laboratory testing, you can effectively evaluate this young patient with uncontrolled hypertension and identify potential underlying causes or target organ damage.