Pituitary Disorders: SIADH versus DI

Between SIADH and DI, which one retains and which one excretes too much water? If you’re a bit confused between the two, here’s a quick rundown of the two pituitary disorders that are commonly included in major exams.

Posterior Pituitary (pee-pee) is for ADH

Let’s backtrack a bit and review on the primary function of the posterior pituitary gland.

The posterior pituitary is mainly responsible for the secretion of the antidiuretic hormone (ADH) which is the hormone that triggers either water retention or excretion. Water excretion is in the form of urine (pee-pee).

The antidiuretic hormone, as what we’ve previously discussed, is similar to a turnstile in a train station or a fair that puts water back to be reabsorbed by the body. ADH acts directly on the exit portals to control fluid that goes in or out. Antidiuretic hormone prevents the kidneys from excreting water out of the body.

            Posterior pituitary (pee-pee) = ADH = water excretion or absorption

Syndrome of Inappropriate Antidiuretic Hormone (SIADH)

The syndrome of inappropriate antidiuretic hormone (SIADH) is a disorder that has increased antidiuretic hormone. You can remember this by breaking down SIADH to SI and ADH.

Recall your Spanish course wherein “si” in English is “yes.” Now, consider “Si” as “mas” or in English, “more.” So, when applied to SI ADH, you’re basically saying, “Yes ADH, we have more ADH.” This technically means that when you have SIADH, you have increased water reabsorption.

            SIADH = “Si ADH, mas ADH” = Yes ADH, more ADH = increased water reabsorption

The Signs and Symptoms of SIADH

When you think of someone who has SIADH (more ADH), you have to consider that there is increased water retention. So, what happens if there is increased retention of water inside the body?

  1. Fluid volume overload, bounding pulses, jugular vein distention (JVD), increased blood pressure that may lead to headaches
  2. Laboratory values – hemodilution
  3. Edema
  4. Urine analysis – high specific gravity (1.03), brown or dark, odorous urine

Diabetes Insipidus (DI)

Diabetes insipidus is a condition that’s telling your ADH to get lost or die; thus, you can remember diabetes insipidus as DI ADH for “die ADH.” When there is less or no ADH in the body, water is not reabsorbed by the body.

            DI = Die ADH = less or no ADH = increased water excretion

The Signs and Symptoms of DI

So, DI is just the opposite of SIADH. When your client has DI, there is decreased water retention and increased urine output. So, what happens to a client who has DI?

  1. Weak thread pulse, poor skin turgor due to dehydration
  2. Low blood pressure
  3. Laboratory values – hemo-concentrated, increased hemoglobin and hematocrit
  4. Sinkable episodes – very dizzy and faint due to decreased fluid retention
  5. Urine analysis – very low specific gravity (1.005), diluted urine
  6. Increased potassium and sodium in the urine

Points to Remember

In a nutshell, the signs and symptoms of SIADH and DI are mainly because of ADH. When you have too much of ADH, you have SIADH. On the other hand, if you have decreased ADH, you have DI. You can also put it this way:

  • SIADH – In the body and not in the potty
  • DI – In the potty and not in the body

So, that’s the simplified explanation on the difference between SIADH and DI. I hope this cleared up the confusion and helped you distinguishing how SIADH and DI work.

For more fun and insightful discussions of other nursing fundamentals and diseases, visit simplenursing.com.

Overview of the Endocrine System & Pituitary Gland Pt 1

The endocrine system is composed of different glands and organs that are primarily responsible for producing hormones, namely:

  • Hypothalamus
  • Pituitary gland
  • Thyroid gland
  • Parathyroid glands
  • Adrenal gland
  • Pancreas

Due to the extensive scope of the endocrine system, memorizing every single hormone and every single function is quite challenging. Just trying to figure out what gland or organ a specific hormone is originating from and its primary function can eat so much of a student’s study time.

Students can try to study, master, and go through every single gland or organ, or they can choose the easier, more simplified way. How? By easily figuring out where it starts and how it branches out.

The Coffee Plantation

Consider your hypothalamus as your main creator of coffee beans. Don’t stress out about the pathophysiology for now. Just focus on your hypothalamus as your plantation for coffee beans that are used by coffee shops.

So, whenever you think about the hormones produced inside the body, namely:

  • Insulin – produced in the pancreas to allow glucose inside the cells
  • Antidiuretic hormone (ADH) – regulates water that affects blood pressure
  • Oxytocin – helps with cervical dilation
  • Corticotropin-releasing hormone – suppresses appetite
  • Growth hormone – responsible for physical development in children

All of these hormones are generally produced in the coffee plantation – the hypothalamus. A lot of people get confused when different systems get involved.

The Storage Facility and Distribution Company

The pituitary gland acts like the coffee plantation’s storage facility and distribution company by packing the hormones up and shipping them out to specific parts of the body.

The pituitary gland is broken down into two parts:

  1. Anterior pituitary (AP) – the front part of the pituitary gland
  2. Posterior pituitary (PP) – back part of the pituitary gland

We will be mainly focusing on the posterior pituitary gland.

The Posterior Pituitary Gland

The posterior pituitary gland is primarily associated with your antidiuretic hormone (ADH) or the hormone that’s primarily responsible for our pee-pee.

Antidiuretic hormone is that hormone that controls the release of fluids from the body most especially from the kidneys in the form of urine. The posterior pituitary will communicate with the kidneys (exit portals) to allow pee-pee to pass.

Think of the antidiuretic hormone as a turnstile. For those who are unfamiliar with the term, turnstile is like a small gate that allows one person at a time to go through and to be able to pass; you would need a ticket, a coin, or a card. You can see turnstiles fairs, train stations and, entrances of buildings.

ADH Main Function

Now that we’ve established what a turnstile is and how it is similar to an ADH, we’ll go to its function.

ADH, like a turnstile, accumulates H2O, puts it back in the body, not allowing water to go out through the process of reabsorption. Every time fluid wants to go out, turnstile ADH will bring water right back in.

But what happens if a problem occurs with your ADH – too much or too little production? Issues with ADH will lead to either SIADH or diabetes insipidus (DI). These two conditions will be discussed and broken down in our next lecture.

See you there!

Adrenal Glands Disorder Review: Cushing’s vs Addison’s

Probably one of the most requested topics, Cushing’s and Addison’s Disease are two adrenal gland disorders that are both confusing and difficult to identify.

A lot of people, especially nursing students, usually get the two diseases mixed up. When discussing Cushing’s Syndrome and Addison’s Disease, you will be talking about a lot of hormones involved. For that reason, SimpleNursing.com is cutting out the confusing parts and will be focusing on what really matters and what will come out in your NCLEX® exams.

The Gist

The contrasting factor between Cushing’s and Addison’s is cortisol; one is too much, and other is too little.

  • Cushing’s Syndrome – increased cortisol
  • Addison’s Disease – decreased cortisol

To better understand how the two diseases occur, we first need to know how cortisol is produced inside the body.

The Starting Point

All hormone regulation starts in the pituitary gland. The pituitary gland consists of the anterior pituitary and the posterior pituitary. Between the two, it’s the anterior pituitary that’s responsible for secreting the hormone that is responsible for Cushing’s and Addison’s – the adrenocorticotrophic hormone (ACTH). So, that is what we’ll be focusing on.

The ACTH is like a domino hormone that triggers the adrenal release of steroids. You can think of ACTH as a messenger that goes to your adrenal glands (the glands sitting on top of your kidneys) and says, “Hey adrenals, release some hormones.”

Message Received

Once your adrenals receive the message, it will produce MAC. What does M-A-C stand for?

  • M – Mineral steroids (aldosterone)
  • A – Androgens (hair and sex)
  • C – Corticosteroids

Mineral Steroids

One of the notable mineral steroids that the adrenal glands produce is the aldosterone or what Mike likes to call “Aldos Tyrone.” Think of Aldos Tyrone as a bouncer who stands at the door of a nightclub (kidneys). What this bouncer does is he holds back sodium from getting out of the kidneys and because of that, water is also retained.

What happens if there is increased water retention?

  • Increased pressure in the vascular beds or vascular system
  • Increased blood pressure

If Aldos Tyrone is eliminated using an aldosterone blocker (Spironolactone), it will decrease or eliminate sodium from the body and water will follow; thus, decreasing blood pressure.


Androgens, like testosterone, are mainly responsible for the production of hair and sex hormone. Therefore, if you have increased androgens in your body, you will produce a lot of hair, and your sex drive will be heightened.


This is where Addison’s Disease and Cushing’s Syndrome come in. Corticosteroids are your cortisol. Cortisol a natural hormone produced in the body where Prednisone, a known corticosteroid, is derived from.

What are the functions of corticosteroids?

Think of your corticosteroids as your airbags. What is the primary function of an airbag? To protect you from harm caused by vehicular accidents. Corticosteroids are produced to act like an airbag to protect you from the inflammation caused by stress.

Adverse Effects of Corticosteroids

Though corticosteroids help in relaxation, it also triggers water retention. Fluid retention can cause:

  • Increased potassium level
  • Weight gain
  • High blood pressure

Going back to the airbag concept, yes, airbags are great because they save your life, but take up a lot of space; same with corticosteroids. Corticosteroids decrease stress and inflammation but will eventually smother you and add extra weight. Therefore, long-term Prednisone intake can cause water retention and high blood pressure.

Cushing’s versus Addison’s

Taking cortisol as the primary regulatory factor, you can now quickly enumerate the difference between Addison’s Disease and Cushing’s Syndrome.

Addison’s Disease – too little cortisol that leads to:

  • Weight loss
  • Low blood pressure
  • Hair loss
  • Sexual dysfunction

Cushing’s Syndrome – too much cortisol that leads to:

  • Weight gain
  • High blood pressure
  • Thinning of hair
  • Decreased libido and fertility
  • “Smothering” effect

In our next lecture, we will be going into the nitty-gritty details of the signs and symptoms of Cushing’s Syndrome and Addison’s Disease. See you there!