# 🔍 Secondary HTN Screening

## 🚨 REVOLUTIONARY CHANGE: Universal PA Screening

**Class 1 Recommendation:** Screen ALL resistant hypertension patients for primary aldosteronism **REGARDLESS OF POTASSIUM STATUS**. Previous guidelines missed 70-80% of cases by requiring hypokalemia.

### 🧬 Primary Aldosteronism: The Great Masquerader

#### 💡 High-Yield Clinical Pearls

- **Normokalemic disease predominates:** 70-80% of primary aldosteronism patients have normal potassium
- **Cardiovascular risk exceeds BP alone:** Independent predictor of cardiovascular events beyond hypertension
- **Targeted therapy reduces excess risk:** Mineralocorticoid receptor antagonism provides specific cardiovascular protection
- **Prevalence in resistant HTN:** 20% of patients with treatment-resistant hypertension have primary aldosteronism

#### 🎯 Screening Indications (Class 1)

🔴

##### Resistant Hypertension

BP above goal despite **3 optimally-dosed antihypertensives** including diuretic

Screen ALL patients 💊

##### Hypokalemia + HTN

**Spontaneous:** K+ \<3.5 mEq/L\
**Diuretic-induced:** K+ \<3.0 mEq/L

🧬

##### Adrenal Incidentaloma

Any patient with incidentally discovered **adrenal nodule** and hypertension

👥

##### Family History

First-degree relative with **primary aldosteronism** or early-onset HTN

⚡

##### Young-Onset HTN

Diagnosis **before age 35**, especially if severe

#### 🧪 Screening Protocol: Aldosterone-to-Renin Ratio (ARR)

##### 💎 2025 Guideline Innovation

**No medication washout required for initial screening.** Most antihypertensives can be continued except mineralocorticoid receptor antagonists, which must be discontinued for at least 4 weeks.

#### 🧮 ARR Calculator

Calculate aldosterone-to-renin ratio and interpret results

Morning Aldosterone (ng/dL) Normal: 4-31 ng/dL Plasma Renin Activity (ng/mL/hr) Normal: 0.6-4.3 ng/mL/hr Patient Position Potassium Level (mEq/L) Correct to \>3.5 before testing ARR = 30.0 \| Interpretation: Positive screen - requires confirmatory testing

##### 📊 ARR Interpretation Guidelines:

- **ARR \<20:** Primary aldosteronism unlikely
- **ARR 20-30:** Intermediate probability - consider repeat testing
- **ARR \>30:** High probability - proceed to confirmatory testing
- **ARR \>50 + PAC \>20:** Very high probability - likely positive confirmatory test

#### 💊 Medication Effects on ARR Testing

[TABLE]

#### 🎯 Confirmatory Testing (When ARR Positive)

##### 📋 Oral Sodium Loading

High-salt diet (6g/day) × 3 days → 24-hour urine aldosterone. Positive if \>12 μg/24hr

##### 💉 Saline Infusion Test

2L normal saline over 4 hours → plasma aldosterone. Positive if \>10 ng/dL

##### 💊 Captopril Challenge

25-50mg captopril → repeat ARR after 2 hours. Positive if no suppression

### 🫀 Renal Artery Stenosis: Medical vs Interventional

##### 💡 Evidence-Based Management Shift

**Medical therapy is Class 1 recommendation** for atherosclerotic renal artery stenosis. CORAL and ASTRAL trials showed no benefit of revascularization over optimal medical therapy for most patients.

#### 🎯 Screening Indications

- **Resistant hypertension** with preserved renal function
- **Acute kidney injury** with ACE inhibitor or ARB initiation
- **Recurrent flash pulmonary edema** with preserved EF
- **Asymmetric kidney size** (\>1.5 cm difference)
- **Abdominal bruit** in young patient
- **Early-onset severe hypertension** (\<30 years old)

#### 🔬 Diagnostic Approach

##### CT Angiography

**Preferred initial test.** High sensitivity/specificity, evaluates anatomy. Contrast nephropathy risk in CKD.

##### MR Angiography

**CKD-friendly option.** No nephrotoxic contrast. May overestimate stenosis severity.

##### Renal Duplex

**Operator-dependent.** Peak systolic velocity \>180 cm/s suggests stenosis. Non-invasive screening option.

#### ⚕️ Management Strategy

##### 📚 Medical Therapy (Class 1)

- ACE inhibitors or ARBs (monitor creatinine)
- Calcium channel blockers
- Statin therapy
- Antiplatelet therapy
- Smoking cessation
- Diabetes management

##### 🔧 Revascularization (Class 2a)

- Resistant HTN despite optimal medical therapy
- Recurrent flash pulmonary edema
- Progressive renal insufficiency with RAAS inhibition
- Fibromuscular dysplasia (often curative)

## 🔍 Additional Secondary Causes: Recognition and Screening

💜

#### Pheochromocytoma

**Classic Triad:** Headache Palpitations Diaphoresis **🧪 Screening:**

24-hr urine catecholamines/metanephrines or plasma metanephrines

- Paroxysmal hypertension
- HTN crisis with anesthesia
- Family history of MEN syndromes
- Adrenal incidentaloma

😴

#### Obstructive Sleep Apnea

**50-80%**

Prevalence in resistant HTN

**🧪 Screening:**

STOP-BANG questionnaire, overnight sleep study

- Morning hypertension pattern
- Witnessed apneas
- Excessive daytime sleepiness
- Obesity, large neck circumference

🫀

#### Coarctation of Aorta

**Key Finding:**

Upper-lower extremity BP gradient **\>20 mmHg**

**🧪 Screening:**

4-extremity BP measurements, echocardiography

- Young-onset hypertension
- Weak/delayed femoral pulses
- Rib notching on chest X-ray
- Bicuspid aortic valve

💊

#### Drug-Induced HTN

**Key Concept:**

Medication history review is **essential**

**Common Culprits:** NSAIDs Decongestants OCPs Steroids

- NSAIDs (including COX-2)
- Sympathomimetics
- Oral contraceptives
- Licorice, energy drinks

## 📚 Sources

1.  **Funder JW, Carey RM, Mantero F, et al.** The Management of Primary Aldosteronism: Case Detection, Diagnosis, and Treatment: An Endocrine Society Clinical Practice Guideline. *J Clin Endocrinol Metab.* 2016;101(5):1889-1916. [PMID: 26934393](https://pubmed.ncbi.nlm.nih.gov/26934393/). \[Source for: PA screening with ARR; expanded screening criteria including resistant HTN, hypokalemia, adrenal incidentaloma.\]
2.  **Whelton PK, Carey RM, Aronow WS, et al.** 2017 ACC/AHA Guideline for High Blood Pressure in Adults. *Hypertension.* 2018;71(6):e13-e115. [PMID: 29133356](https://pubmed.ncbi.nlm.nih.gov/29133356/). \[Source for: secondary HTN screening triggers — resistant HTN, age \<30, severe HTN, sudden onset, target organ damage out of proportion.\]
3.  **Brown C, Clark D, Jones DW.** Updates in the 2025 AHA/ACC Hypertension Guideline. *Curr Hypertens Rep.* 2026;28(1). [PMID: 41843050](https://pubmed.ncbi.nlm.nih.gov/41843050/). \[Source for: 2025 update — expanded primary aldosteronism screening to ALL stage 2 / resistant HTN patients.\]
4.  **Lenders JW, Duh QY, Eisenhofer G, et al.** Pheochromocytoma and paraganglioma: an endocrine society clinical practice guideline. *J Clin Endocrinol Metab.* 2014;99(6):1915-1942. [PMID: 24893135](https://pubmed.ncbi.nlm.nih.gov/24893135/). \[Source for: pheochromocytoma screening (plasma free or 24h urine fractionated metanephrines), test sensitivity 96-100%, specificity by test.\]
5.  **Bornstein SR, Allolio B, Arlt W, et al.** Diagnosis and Treatment of Primary Adrenal Insufficiency: An Endocrine Society Clinical Practice Guideline. *J Clin Endocrinol Metab.* 2016;101(2):364-389. [PMID: 26760044](https://pubmed.ncbi.nlm.nih.gov/26760044/). \[Source for: adrenal hormone disorders evaluation framework relevant to secondary HTN.\]
6.  **Gornik HL, Persu A, Adlam D, et al; First International Consensus on the diagnosis and management of fibromuscular dysplasia.** *J Hypertens.* 2019;37(2):229-252. [PMID: 30640867](https://pubmed.ncbi.nlm.nih.gov/30640867/). \[Source for: renovascular HTN — fibromuscular dysplasia evaluation and management.\]

### 🎯 Secondary HTN Screening: Key Learning Points

#### 🧬 Primary Aldosteronism

- Screen ALL resistant HTN regardless of K+
- Most patients are normokalemic (70-80%)
- ARR screening without medication washout
- MR antagonists reduce cardiovascular risk

#### 🫀 Renal Artery Stenosis

- Medical therapy preferred (Class 1)
- Revascularization for specific indications
- FMD vs atherosclerotic different outcomes
- Monitor renal function with RAAS inhibitors

#### 🔍 Clinical Approach

- High index of suspicion in resistant HTN
- Systematic evaluation prevents missed diagnoses
- Targeted therapy improves outcomes
- Cost-effective when appropriately applied

📚 For Educational Purposes Only

© 2025 University of Dubuque PA Program - All Rights Reserved


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