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Can you explain concisely each

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The table covers 9 causes of secondary hypertension (and related endocrine/structural conditions), listing the first-line screening test and confirmatory/imaging workup for each. Here's a concise breakdown:

1. Primary Aldosteronism

Excess aldosterone from the adrenal gland (adenoma or bilateral hyperplasia) causes hypertension + hypokalemia.
  • First-line: Aldosterone:Renin Ratio (ARR) >30 — aldosterone is high while renin is suppressed.
  • Confirmatory: CT adrenal (to spot adenoma); adrenal vein sampling (AVS) determines if one or both glands are overactive; saline infusion test confirms autonomous aldosterone secretion (failure to suppress = positive).

2. Pheochromocytoma

Catecholamine-secreting tumor of the adrenal medulla causing episodic severe hypertension, headache, sweating, palpitations.
  • First-line: 24h urine metanephrines/catecholamines or plasma metanephrines (very sensitive).
  • Confirmatory: CT/MRI adrenal to locate the tumor; MIBG scan used if metastatic disease is suspected.

3. Cushing's Syndrome

Excess cortisol (from pituitary ACTH, adrenal tumor, or exogenous steroids) — central obesity, striae, hypertension.
  • First-line: 24h urine free cortisol or overnight 1 mg dexamethasone suppression test (DST) — normal cortisol suppresses to <50 nmol/L.
  • Confirmatory: CRH stimulation test + Inferior Petrosal Sinus Sampling (IPSS) to distinguish pituitary vs. ectopic ACTH source; pituitary MRI for adenoma.

4. Renovascular HTN

Renal artery stenosis (atherosclerosis or fibromuscular dysplasia) triggers RAAS activation → hypertension.
  • First-line: Renal Doppler ultrasound (detects reduced flow/velocity); captopril renogram (ACE inhibitor causes asymmetric drop in GFR in stenotic kidney).
  • Confirmatory: MR or CT angiography of renal arteries; Digital Subtraction Angiography (DSA) is the gold standard.

5. Coarctation of Aorta

Congenital narrowing of the aorta, typically distal to the left subclavian, causing upper-limb hypertension with weak femoral pulses.
  • First-line: BP measured in all 4 limbs (upper > lower); CXR shows rib notching (collateral vessels eroding ribs) and the '3 sign' (aortic indentation).
  • Confirmatory: Echocardiogram; CT/MRI aortogram for precise anatomy.

6. Sleep Apnea

Repetitive nocturnal hypoxia activates the sympathetic nervous system → sustained hypertension.
  • First-line: Berlin Questionnaire and Epworth Sleepiness Scale — clinical screening tools for risk/daytime sleepiness.
  • Confirmatory: Polysomnography (PSG) — overnight sleep study measuring AHI; gold standard.

7. Hypothyroidism

Low thyroid hormone increases systemic vascular resistance → diastolic hypertension.
  • First-line: TSH (elevated in primary hypothyroidism).
  • Confirmatory: Free T4 (low); anti-TPO antibodies (positive in Hashimoto's thyroiditis).

8. Acromegaly

Excess growth hormone (GH) from a pituitary adenoma — enlargement of hands, feet, jaw; hypertension via sodium retention.
  • First-line: IGF-1 level (stable, reliable marker of GH excess).
  • Confirmatory: GH suppression test (oral glucose load should suppress GH to <1 µg/L — failure confirms diagnosis); pituitary MRI for adenoma.

9. Renal Parenchymal Disease / CKD

Damaged nephrons reduce sodium excretion and activate RAAS → volume-dependent hypertension.
  • First-line: eGFR (estimates kidney function); urine albumin:creatinine ratio (ACR) detects proteinuria; urine microscopy (casts suggest glomerular disease).
  • Confirmatory: Renal biopsy if glomerulonephritis is suspected (determines exact histological pattern for targeted treatment).
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