April 7, 2016 - Secondary Hypertension Overview

Question 1

When to Think of Secondary Hypertension

Answer 1

This is a diagnosis of exclusion, so you want to rule out primary hypertension first.

Can often be seen in patients who should not be presenting with HTN for their age, are resistant to 3 or more medications, have obvious secondary clues, have a hypertensive urgency/emergency, and are compliant with their medications.

Question 2

Conn’s Syndrome

Answer 2

AKA primary aldosteronism

Excess production of aldosterone by the adrenal glands resulting in low renin levels.

The classic triad of signs and symptoms are hypertension, hypokalemia, and metabolic alkalosis.

To diagnose you can use the aldosterone/renin ratio. Normally, you would expect renin to be in the normal range and aldosterone to be in the normal range. If the adrenal glands are producing too much aldosterone, renin will be suppressed and the ratio of aldosterone to renin will be abnormal.

Question 3

How to Diagnose Conn’s Syndrome

Answer 3

To diagnose you can use the aldosterone/renin ratio.

Normally, you would expect renin to be in the normal range and aldosterone to be in the normal range. If the adrenal glands are producing too much aldosterone, renin will be suppressed and the ratio of aldosterone to renin will be abnormal.

Question 4

Effect of Aldosterone

Answer 4

Aldosterone acts on the principal cells in the kidney to increase sodium-potassium ATPase activity, epithethial sodium channels (ENaC), and renal outer medullary potassium channels (ROMK). These actions increase sodium reabsorption and potassium secretion.

Since more sodium is reabsored and more potassium is excreted (3Na⁺ and 2K⁺), the lumen becomes more positive allowing chloride to follow the sodium, and water to follow the chloride/sodium which increases the amount of fluid.

Aldosterone also acts on intercalated cells to stimulate an apical proton ATPase which causes proton secretion that acidifies urine and alkalizes the extracellular fluid.

All together, this causes HTN, metabolic alkalosis, and hypokalemia.

Question 5

Cushing’s Disease

Answer 5

Increased secretion of adrenocorticotropic hormone (ACTH) from the anterior pituitary.

This is often a result of the pituitary adenoma or excess production of hypothalamus corticotropic release hormone (CRH) that stimulates the synthesis of cortisol by the adrenal glands.

Common symptoms include weight gain, HTN, red face, extra neck fat, moon face etc.

Question 6

Acromegaly

Answer 6

A rare syndrome that results when the anterior pituitary gland produces excess growth hormone (GH) after epiphyseal plate closure at puberty.

If GH is produced in excess prior to the epiphyseal plate closure, the result is gigantism.

98% of the cases of acromegaly are due to the overproduction of growth hormone by a benign adenoma tumor of the pituitary gland.

Can cause secondary hypertension

Question 7

Pheochromocytoma

Answer 7

A neuroendocrine tumor of the medulla of the adrenal glands which secretes norepinephrine and epinephrine.

Causes episodes of massive hypertension as adrenaline is essentially released into the blood.

Diagnosed through a 24-hour urine collection.