anatomy

Primary Essential Hypertension vs Secondary Hypertension: Causes and Health Effects of High Blood Pressure [Biology, MCAT, USMLE]

In this quick, easy-to-understand lesson, we learn about secondary hypertension for USMLE and medicine. Secondary hypertension is defined as high blood pressure (>140/90 or >130/80) caused by an underlying disease, medical condition, or drugs. While primary hypertension comprises of the majority of hypertension cases (90%), only 10% of patient cases is secondary hypertension.

Primary Hypertension vs Secondary Hypertension: What is primary hypertension? Read our first primary essential Hypertension USMLE lesson here to learn about the differences between primary hypertension and secondary hypertension.

There are many different causes of secondary hypertension, including chronic kidney disease, obstructive sleep apnea, NSAIDS drugs, among many.

Determinants of Blood Pressure

Health Effects of High Blood Pressure

Blood Pressure = Cardiac Output x Total Peripheral Resistance

BP = CO x TPR

Bloor pressure can increase by either increased cardiac output (CO) or increased total peripheral resistance (TPR).

Cardiac Output on Blood Pressure

An example of increased cardiac output causing high blood pressure is increased renal salt and water retention. When more salt and water is retained in your body, cardiac output increases.

Total Peripheral Resistance

Remember that arterioles are the blood vessels with the highest resistance. Therefore, arterioles play a major role in affecting total peripheral resistance. When arterioles are constricted by vasoconstrictors (catecholamines), TPR increases. The sympathetic nervous system can also increase TPR.

TPR: arterioles (Increase by vasoconstrictors or Increase by sympathetic nervous system)

Chronic Kidney Disease

Over 80% of patients with chronic kidney disease have hypertension. Why? In chronic kidney disease, kidneys are not working well and specifically cannot excrete sodium well. Thus, there is higher sodium retention. Chronic kidney disease can also cause increased renin-angiotensin-aldosterone activity and sympathetic nervous system activity, which both can increase hypertension.

Obstructive Sleep Apnea

Sympathetiac nervous system is ramped up because of sleep apnea, leading to hypertension.

NSAIDS on Hypertension

Drugs that cause secondary hypertension. NSAIDS: like ibuprofen, anproxen, indomethacin, ketorolac, diclofenac. NSAIDS are known as Nonsteroidal anti-inflammatory drugs. NSAIDS inhibit cyclooxygenase (COX) in kidneys. Cycloxygenase is an enzyme that converts arachidonic acid into prostaglandins. When cyclooxygenase is inhibited by NSAIDS, there is decreased synthesis of prostaglandins. PGE-2 plays a specific role in renal vasodilation in afferent arterioles. , so decreased PGE-2 can lead to hypertension. PGE-2 Afferent arteriole vasoconstricts, reducing renal blood flow and glomerular filtration rate, deceasing sodium/water excretion, and leading to hypertension.

NSAIDS –| (inhibit) Cyclooxygenase –> PGE-2

Decreased PGE-2 –> Vasoconstriction in afferent arteriole –> Decreased renal blood flow + Decreased Glomerular Filtration Rate –> Hypertension

Oral Contraceptive Pills that cause secondary hypertension

Estrogen and progesterone increase blood pressure

Hypertension: Causes and Health Effects of High Blood Pressure

Pseudoephedrine can cause Secondary Hypertension

Pseudoephedrine is a nasal decongestant and alpha-1 agonist. Its molecular structure is similar to epinephrine. Epinephrine constricts blood vessels in the nasal passage. Likewise, pseudoephedrine constricts blood vessels in the nasal passage. Vasoconstriction –> leads to decreased nasal blood flow.

Some of you may be thinking, “Wait, doesn’t epinephrine cause vasodilation?” Well, you’re not wrong. Epinephrine causes both vasodilation and vasoconstriction. Specifically, vasodilation for skeletal muscle via B2 receptor, and vasoconstriction in skin and kidneys and the nasal passage via Alpha-1 receptor!

Cyclosporine and Tacrolimus

Immunosuppressants

Calcineurin inhibitors and cause renal vasoconstriction because of salt/water retention. The best drug to treat hypertension yet still treats the same conditions is diltiazem, which treats hypertension and still has equally good efficacy for lower dose cyclosporine.

Click and check out these popular articles for more information: 🙂

Hypertension: Causes and Health Effects of High Blood Pressure

Circulatory System: Blood Flow Pathway Through the Heart

Circulatory System: Heart Structures and Functions

Ductus Arteriosus Vs Ductus Venosus Vs Foramen Ovale: Fetal Heart Circulation

Cardiac Arrhythmias: Definition, Types, Symptoms, and Prevention

Upper Vs Lower Respiratory System: Upper vs Lower Respiratory Tract Infections

Seven General Functions of the Respiratory System

Digestive System Anatomy: Diagram, Organs, Structures, and Functions

Kidney Embryology & Development: Easy Lesson

Psychology 101: Crowd Psychology and The Theory of Gustave Le Bon

Support Us!

Thank you for visiting, and we hope you find our free content helpful! Our site is run 100% by volunteers from around the world. Please help support us by buying us a warm cup of coffee! Many thanks to the kind and generous supporters and donors for doing so! 🙂

$1.39

 Copyright © 2021 Moosmosis: All Rights Reserved

All rights reserved. This essay or any portion thereof may not be reproduced or used in any manner whatsoever
without the express written permission of the publisher. 

Moosmosis Facebook Community


Please Subscribe and Like our Facebook page to support our open-access youth education initiatives! 🙂



4 replies »

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s