Medicine Marrow Pg No 975-984 (Endocrinology)

Management of Hypertension - 2023 Guidelines

• Hypertension is a major public health concern, and its management is focused on treating the underlying cause and controlling blood pressure.
• Endocrine causes of hypertension include genetic and acquired conditions.
• Genetic causes include monogenic forms of endocrine hypertension or low renin hypertension, such as Liddle Syndrome, Apparent Mineralocorticosteroid Excess, and Glucocorticoid Remediable Hyperaldosteronism.
• Acquired causes include Primary Hyperaldosteronism, a triad of high blood pressure, metabolic alkalosis, and hypokalemia.
• Secondary hypertension should be ruled out before diagnosing primary hypertension, especially when the patient is diagnosed with hypertension before 40 years old or has resistant hypertension, which is uncontrolled hypertension with 3 drugs including diuretics, or when the patient has hypertension with target organ damage.

Investigation & Treatment

• Investigate hypertension through a series of tests, including ultrasound with renal artery doppler, urine albumin and creatinine analysis, renal function tests, serum electrolytes (Na, K, Ca, P), 24-hour urine fractionated metanephrines, thyroid function tests, parathyroid hormone levels, and left ventricular hypertrophy assessment.
• Treatment depends on blood pressure levels and the presence of complications. Generally, start with single drug therapy and lifestyle changes.
• Target blood pressure varies based on conditions.
• Medications including ACE inhibitors, ARBs, calcium channel blockers, thiazide/thiazide-like diuretics, and beta-blockers are used to control blood pressure.
• Beta-blockers are preferred for specific cases like coronary artery disease, atrial fibrillation, and heart failure with reduced ejection fraction.
• European Society of Hypertension (ESH) recommends starting therapy with ACE inhibitors and calcium channel blockers, followed by incorporating thiazide-like diuretics if the blood pressure is not controlled.
• Resistant hypertension requires further investigation to rule out secondary causes and then specific medications based on kidney function, such as spironolactone (eGFR > 30) or chlorthalidone (eGFR ≤ 30).

Types of Hypertension

• Primary hypertension is the most common type, accounting for 90-95% of cases.
• Secondary hypertension accounts for 5-10% of cases and is caused by underlying medical conditions.
• Risk factors:
  • Heritability: The most important factor for primary hypertension.
  • Obesity and weight gain: The most important risk factor for primary hypertension.
  • Diet: High intake of sodium, low calcium, low phosphate, and low magnesium.
  • Lifestyle factors: Smoking, alcohol, physical inactivity, stress, and genes like Alpha adducin gene.
  • Family history: Both parents with hypertension increases the risk to 30-40%, while a single parent with hypertension increases the risk to 25%.

Pathophysiology

• Vasoconstrictors:
  • Angiotensin II
  • Endothelin
  • Sympathetic nervous system
  • Arginine vasopressin
  • Reactive oxygen species
• Vasodilators (Protective factors):
  • Nitric oxide
  • Atrial natriuretic peptide
  • Brain natriuretic peptide
  • Adrenomedullin
  • Prostacyclin
  • Adiponectin

Important Note:

• Beta-blockers mainly reduce cardiac output, making them less preferred as first-line drugs.

Ambulatory Blood Pressure Monitoring (ABPM)

• ABPM measures blood pressure over a 24-hour period, capturing diurnal variation and providing a more comprehensive picture of blood pressure fluctuations.
• Measurements are taken during daytime (awake), nighttime (asleep), and calculated to determine the 24-hour mean blood pressure.
• Home blood pressure monitoring can also be used to assess blood pressure readings in a familiar environment.
• Cutoff values for diagnosing hypertension using ABPM are provided in the document.

Secondary Hypertension

• Carefully evaluate for underlying conditions that might be causing secondary hypertension, including renal and cardiac causes.
• Potential conditions include:
  • Kidney disease
  • Coarctation of the aorta
  • Obstructive Sleep Apnea Syndrome (OSAS)
  • Thrombotic Microangiopathy
  • Chronic Glomerulonephritis (IgA/MPGN)
  • Reno-vascular causes like Takayasu arteritis, Fibromuscular dysplasia, and Atherosclerosis.

ECG Changes and Treatment for Potassium Imbalance

• Potassium imbalance can cause significant ECG changes, affecting the QRS complex, P wave, and T wave.
• Approximate serum potassium levels correlate with specific ECG changes.
• Acute Treatment (for emergency situations):
  • 10% Calcium Gluconate: Provides immediate stabilization of the myocardium by raising the action potential threshold.
  • Insulin Dextrose: Shifts Potassium into cells.
  • Albuterol: A beta-agonist that can shift potassium into cells.

Definitive Treatment

• For chronic potassium imbalance, definitive treatment may include dialysis for patients with Chronic Kidney Disease (CKD).

Hepatology

• The liver is a complex organ with distinct zones and blood vessel networks.

Vitelline Veins

• The vitelline veins, derived from the yolk sac, are crucial for embryonic liver development.
• They divide into superior and inferior sections, contributing to the formation of the common hepatic vein and inferior portal vein.
• Falciform ligament: Separates the liver lobes anteriorly, dividing the liver into left and right anatomical regions.
• Cantlie's line: An imaginary line dividing the liver into left and right regions.

Liver Histology

• Microscopic images depict the histological structure of the liver, including hepatic acini.
• The document also mentions specific diseases related to the liver's structure, including ischemic hepatitis and paracetamol poisoning.

Basics of Development & Anatomy of Liver

• The liver develops from endodermal and mesodermal origins.
• The liver is a vital organ with diverse functions.
• Lobule: The basic functional and structural unit of the liver.
• The lobule's periphery contains the portal tract with a mixture of blood supply from the hepatic artery and the bile duct.
• The lobule's centre is where the hepatic vein is located, which is not covered by Glisson's capsule.
• The liver lobule is surrounded by Glisson's capsule, which is made up of connective tissue, stellate (Ito) cells, Kupffer cells, and sinusoids.
• Pathology: Cirrhosis is characterized by the replacement of liver lobules with nodules connected by fibrous septae.
• Fetal cardiac defects are associated with liver development issues.
• Hepatocytes and cholangiocytes contribute to liver function.
• The septum transversum, a mesodermal structure, forms connective tissue in the liver.