A 52-year-old man with newly diagnosed hypertension (BP 162/104 mmHg) undergoes evaluation for secondary causes. Which of the following clinical or biochemical findings is NOT consistent with a diagnosis of secondary hypertension?

Explanation

## Clinical Features Distinguishing Essential from Secondary Hypertension **Key Point:** Secondary hypertension presents with specific clinical or biochemical "red flags" that distinguish it from essential (primary) hypertension. Insidious onset with stable biochemistry is typical of essential hypertension. ### Red Flags for Secondary Hypertension | Feature | Associated Cause | Why It Matters | | --- | --- | --- | | Hypokalemia + metabolic alkalosis + low PRA | Primary hyperaldosteronism | Specific hormonal signature | | Episodic symptoms (headache, palpitations, sweating) | Pheochromocytoma | Paroxysmal catecholamine release | | Abdominal bruit + sudden onset + ↑ creatinine | Renal artery stenosis | Hemodynamic obstruction | | Young age (< 30) + resistant HTN | Various secondary causes | Atypical presentation | | Rapid worsening of controlled HTN | Acute secondary cause | Acute change in baseline | | Hypertension + hypokalemia + low PRA | Cushing syndrome or hyperaldosteronism | Mineralocorticoid excess | ### Essential (Primary) Hypertension — Typical Features **High-Yield:** Essential hypertension (90–95% of cases) is characterized by: - Gradual, insidious onset over months to years - Stable blood pressure without paroxysmal episodes - Normal serum electrolytes and renal function (unless chronic) - No specific biochemical abnormality - Family history of hypertension - Age 30–50 years at diagnosis **Clinical Pearl:** A patient with 10 years of gradual BP rise, stable renal function, and normal electrolytes fits the profile of essential hypertension — NOT secondary hypertension. This patient does not require extensive secondary cause workup unless red flags emerge. ### When to Investigate for Secondary Causes 1. **Age-related red flags:** Onset < 30 or > 55 years 2. **Acute change:** Sudden worsening of previously stable HTN 3. **Resistance:** Uncontrolled on ≥3 antihypertensive agents 4. **Biochemical clues:** Hypokalemia, elevated creatinine, abnormal aldosterone/renin ratio 5. **Symptom cluster:** Episodic symptoms (pheochromocytoma), proximal weakness (Cushing), etc. **Warning:** Do not over-investigate essential hypertension. The presence of a stable, gradual course with normal biochemistry is reassuring and argues against secondary causes.