Week 4 May 22 10 am Renal Artery Stenosis, Fibromuscular Dysplasia, Hyperaldosteronism & Pheochromocytoma

Renal Artery Stenosis

• Can affect one or both sides of the kidneys.

• Often categorized into:

  • Renal Artery Stenosis due to Atherosclerosis:

    • Common in older populations.

    • Risk Factors:

      • Age.

      • Male gender.

      • Caucasian ethnicity.

      • Smoking.

      • Diabetes.

      • High lipid panels (risks of atherosclerosis).

  • Fibromuscular Dysplasia:

    • Not caused by atherosclerosis.

    • More common in women.

• Clinical Clues:

  • High blood pressure in very young patients.

  • Late-onset hypertension in previously healthy individuals.

  • Resistance to at least three antihypertensive medications.

  • Significant increase in BUN and creatinine levels after starting ACE inhibitors or ARBs.

• Clinical Presentation:

  • High blood pressure is the primary sign.

  • Abdominal bruit (right upper quadrant, left, or epigastrium) may be present (up to 80% of cases), but its absence doesn't rule out the condition.

• Workup:

  • Blood work: BUN and creatinine levels to assess kidney function.

  • Urine test: Check for protein spillage.

• Diagnosis:

  • Renal angiogram: Gold standard, typically reserved for cases where diagnosis is unclear after non-invasive tests.

  • Labs: Reduced GFR with elevated serum creatinine can be found. +/- proteinuria

  • Non-invasive tests:

    • Sonogram (usually the first choice).

    • CTA or MRI if sonogram is not feasible.

• Treatment for renal stenosis caused by atherosclerosis:

  • Control blood pressure with suitable medication.

  • Manage lipid levels if atherosclerosis is the cause.

  • Smoking cessation.

  • Revascularization (stent placement).

  • Surgery (in severe cases).

Fibromuscular Dysplasia

• Non-atherosclerotic.

• Etiology: Unknown (potentially genetic or hormonal factors).

• Risk factors: Smoking, female gender, younger population.

• Pathophysiology: Abnormal muscle growth in the artery wall, leading to sections in the renal artery.

• Can affect other arteries like carotid and vertebral arteries.

• Imaging:

  • Appearance described as "pearls on a string".

• Clinical Presentation:

  • High blood pressure.

  • Possible bruit.

• Workup:

  • Labs to check kidney function.

• Diagnosis:

  • Renal angiogram (gold standard).

  • Sonogram (initial non-invasive test).

  • CTA or MRI if needed.

• Treatment:

  • Surgery if all else fails.

  • Blood pressure control.

  • Stent placement if necessary.

Primary Hyperaldosteronism

• Causes secondary hypertension.

• Etiology:

  • Idiopathic.

  • Bilateral adrenal hyperplasia (more common).

  • Unilateral adrenal tumor (Conn syndrome).

• Clinical Presentation:

  • High blood pressure.

  • Hypokalemia (though not always present).

  • Symptoms of hypokalemia: Muscle weakness, fatigue, constipation.

• Screening Recommendations (Endocrine Society):

  • Unexplained hypertension.

  • Resistant hypertension.

  • Hypertension with hypokalemia.

  • Hypertension with sleep apnea.

  • Existing adrenal tumor.

  • Family history of early-onset hypertension.

  • Cerebrovascular accident before age 40.

• Workup:

  • BMP to assess potassium levels.

  • Renin and aldosterone level measurements: Elevated aldosterone.

• Diagnosis (after initial labs):

  • One of four challenge tests to confirm:

    • Oral sodium loading.

    • Saline infusion.

    • Fludrocortisone suppression test.

    • Captopril challenge test.

    • In healthy individuals, these interventions should suppress aldosterone levels. In primary hyperaldosteronism, aldosterone suppression will not occur.

  • Imaging to visualize adrenal glands and guide treatment.

• Treatment:

  • Surgery (for unilateral tumors).

  • Spironolactone (potassium-sparing diuretic).

    • Mechanism: Spironolactone helps increase potassium levels, addressing hypokalemia associated with hyperaldosteronism.

• Spironolactone Drug Card:

  • Clinical Uses:

    • Primary hyperaldosteronism.

    • Heart failure.

    • Hypertension.

    • Hirsutism in PCOS.

  • Adverse Effects:

    • Hyperkalemia.

    • Gynecomastia.

Pheochromocytoma

• Catecholamine-producing tumor.

• Clinical Presentation:

  • Hypertensive crisis.

  • Range of symptoms (may include headache, sweating, palpitations, panic attacks).

• Diagnosis:

  • Elevated catecholamines or metanephrines in blood or urine.

    • Initial step: 24-hour urine collection for catecholamines/metanephrines.

  • Imaging to locate the tumor.

• Treatment (Specific Order):

  1. Nonselective alpha-blockade (to relax arteries and lower blood pressure).

  2. Beta-blocker or calcium channel blocker (to manage heart rate).

  3. Surgery.

     • Rationale: This sequence prevents rebound hypertension.

Question Review

• Question 1:

  • Patient: 50-year-old male with hypertension, diabetes, and proteinuria.

  • Best medication: Lisinopril (ACE inhibitor).

  • Explanation: ACE inhibitors are beneficial for diabetic patients with proteinuria.

• Question 2:

  • Patient: 56-year-old male with nausea, malaise, and low sodium after starting a new blood pressure medication.

  • Likely medication: Hydrochlorothiazide (thiazide diuretic).

  • Explanation: Thiazide diuretics can affect electrolytes and kidney function.

• Question 3:

  • Which class of hypertensive medications should not be used as first-line for essential hypertension without comorbidities?

  • Answer: Beta-blockers.

  • Explanation: Beta-blockers are more appropriate when there are other conditions such as coronary artery disease or CHF.

• Question 4:

  • Which medication should be discontinued in a woman with high blood pressure who is trying to get pregnant?

  • Answer: ACEs and ARBs.