Differential Diagnosis for Hypertension

The patient presents with persistently increased blood pressures, occasional headaches, and increased urine output. The laboratory results and physical examination findings guide the differential diagnosis.

• Single Most Likely Diagnosis

  • A) Autonomous production of aldosterone: This condition, also known as primary aldosteronism, is suggested by the patient's hypokalemia (low potassium level of 2.9 mEq/L) in the presence of hypertension. Aldosterone promotes sodium retention and potassium excretion, which could explain the patient's high blood pressure and low potassium level. The metabolic alkalosis (elevated HCO3– of 32 mEq/L) further supports this diagnosis, as aldosterone increases hydrogen ion excretion, leading to alkalosis.

• Other Likely Diagnoses

  • E) Juxtaglomerular cell hypertrophy and sclerosis: This condition is associated with renin-mediated hypertension. Although the patient's potassium level is low, which could be seen in primary aldosteronism, the possibility of another renin-angiotensin-aldosterone system (RAAS) abnormality cannot be ruled out without further testing.
  • C) Decreased arterial distensibility caused by atherosclerosis: While less likely given the patient's age and lack of other atherosclerotic risk factors, this condition could contribute to isolated systolic hypertension. However, the patient's diastolic blood pressure is also elevated, making this a less likely primary cause.

• Do Not Miss Diagnoses

  • B) Catecholamine-producing tumor: Although less common, a pheochromocytoma (a catecholamine-producing tumor) is a critical diagnosis not to miss due to its potential for severe, episodic hypertension and other life-threatening complications. The patient's occasional headaches could be a symptom, but the lack of other typical symptoms like palpitations or sweating makes this less likely.
  • D) Excess production of atrial natriuretic peptide: This would typically be associated with heart failure, which is not indicated by the physical examination findings (no edema, point of maximal impulse not displaced). However, it's a condition that could lead to hypertension and should be considered in the broader differential.

• Rare Diagnoses

  • Other rare causes of hypertension, such as Cushing's syndrome, hyperparathyroidism, or renal artery stenosis, are not strongly suggested by the patient's presentation or laboratory results but could be considered if initial evaluations do not reveal a clear cause.
  • Renal causes such as renal artery stenosis or parenchymal disease could also be considered, especially given the slightly elevated creatinine level, but the absence of abdominal bruits or other suggestive findings makes these less likely as the primary cause.