Integrative Cases

Question 1

‘Normal’ urine output (for someone who drinks a normal amount of water a day)

Answer 1

800 mL to 3 liters

Question 2

What instructions do you give to a patient with cranial diabetes insipidus who is managing on desmopressin?

Answer 2

Drink to thirst, but only to thirst.

Question 3

What is going on in this esophageal manometry?

Answer 3

Achalasia with pan-esophageal pressurization.

Pan-esophageal pressurization is sometimes an additional finding of achalasia.

Question 4

A 51-year-old woman presents with 4-year history of acid reflux symptoms of retrosternal burning and chest tightness, without significant dysphagia. These symptoms developed initially following an occasional hiccup. A single-contrast barium examination of upper gastrointestinal was performed, which showed the below.

What is the diagnosis?

Answer 4

Corkscrew esophagus

A rare esophageal motility disorder characterized by high amplitude peristaltic contractions in the distal esophagus. The typical clinical symptoms include chest pain, dysphagia or gastroesophageal reflux disease (GERD).

Question 5

The superior laryngeal nerve controls one’s ability to . . .

Answer 5

. . . manipulate their voice pitch

Question 6

Correcting hypernatremia vs hyponatremia

Answer 6

Recent studies have shown that correcting hypernatremia quickly is . . . actually fine. Not a problem. Give that patient as much D5W as they need to get back to isoosmolarity (or asymptomatic) as soon as you can.

It is hyponatremia that can be dangerous to correct, and for this you should correct by no more than 6-8 mEq/L/day

Question 7

___ shape on MRI is classic for a lesion originating in the pituitary

Answer 7

Snowman shape on MRI is classic for a lesion originating in the pituitary.

Happens due to the constriction of the sella in the middle of the mass

Question 8

The recurrent laryngeal nerve innervates. . .

Answer 8

. . . all the muscles of the larynx except the circothyroid muscle.

Question 9

Patient presents with 70 mmHg/palpation, no palpable pedal pulse, abdominal pain, lightheadedness, and tachycardia following trauma. FAST exam of the left upper abdominal quadrant reveals the image below. What are the next steps?

Answer 9

1. CT scan
2. Give fluids
3. RBC transfusion
4. Reverse anticoagulation if on any, but do NOT give procoagulation
5. Trans-catheter vessel repair through induced embolism

Question 10

Normal saline %

Answer 10

0.9%

Question 11

Triphasic central diabetes insipidus response following posterior pituitary or hypothalamic damage

Answer 11

1. Damage to neurons prevents ADH release, causing polyuria and excess water loss for 4-5 days
2. Neurons die, releasing all of their stored ADH and resulting in a very transient SIADH
3. Permanent ADH insufficiency (aka central diabetes insipidus)

Note that not all of the phases will necessarily happen. Sometimes just up to phase 1 or phase 2. It depends on the extent of the damage of the ADH secreting neurons.

Question 12

Why does leuprolide, a GnRH analog, induce hypogonadism?

Answer 12

Because the timing of the pulses is key for proper tropic regulation. If pulses are too infrequent or too frequent, then they will result in a deficiency in the end hormone.

Question 13

Syndrome of anabolic steroid doping

Answer 13

Suppressed LH, FSH, and androgen (usually testosterone) in a syndrome of androgen excess.

High muscle mass, acne, body hair growth, and agitation in the context of testicular atrophy.

Question 14

On CT scan, the spleen and liver. . .

Answer 14

. . . appear very similar in density.

Question 15

On CT scan, free blood. . .

Answer 15

. . . is usually slightly darker gray than intravascular blood, due to coagulation. It should be similar in density to muscle, in comparison to blood in the aorta, the spleen, or the liver, which are all similar in density on CT.

Question 16

Why do so many people with bipolar disorder develop diabetes insipidus?

Answer 16

Because they take lithium!

Lithium is the #1 cause of nephrogenic diabetes insipidus and occurs in 10-15% of those taking the supplement therapeutically.

It is also associated with development of hypothyroidism and hyperparathyroidism.

Question 17

The idea of giving a patient with SIADH 3% saline

Answer 17

It is not that you are giving sodium to correct hyponatremia. Rather, you are forcing the kidney, which is locked into high concentration urine production, to excrete water by giving it solute.

Normal saline may be hypertonic compared to the blood, but it is hypotonic compared to the urine.

Question 18

You have a patient with hypernatremia from cranial diabetes insipidus. You give them ddAVP. However, over the next several hours, their hypernatremia fails to begin correcting. Assuming the diagnosis and dosing are correct, what is going on?

Answer 18

They haven’t had any water.

In order to decrease osmolarity, you need two things: ADH and water intake.

If we were uncertain about the diagnosis or dosing, then inappropriate dosage or nephrogenic diabetes insipidus would also be possible explanations.

Question 19

If you suspect that a patient has posterior pituitary damage during an operation and subsequent drop in ADH, why might you wait before giving desmopressin?

Answer 19

They may not have gone through the second phase of the triphasic response yet, which produces a transient SIADH. In this situation, giving desmopressin would actually be adverse. So, you may wait until you are confident SIADH has passed or won’t happen, then give desmopressin.

In the meantime, you can increase their fluid intake carefully to correct for hypernatremia,

Question 20

Managing acute gout

Answer 20

1. Immediate NSAIDs or steroids
2. Bridge with colchicine to prevent (~2 months)
3. When not had flair for a while, start on allopurinol (giving when having episode might cause worsening due to crystal fracture)

Question 21

What do you tell any patient coming out of surgery that may affect the posterior pituitary given that they may experience any part of the triphasic response?

Answer 21

Drink to thirst, but only to thirst.

And call us if you are not getting thirsty at all or your are drinking abnormal amounts of water.

Question 22

Acromegaly may be confused for a thyroid issue because. . .

Answer 22

. . . excess growth hormone results in a enlarged thyroid.

Question 23

Foley catheter

Answer 23

Catheter that may be inserted up the urethra to collect urine either because the patient cannot contract the bladder or for analysis.

Question 24

Deglutitive inhibition

Answer 24

Happens when lots of fluid/multiple swallows in quick succession.

Esophageal is turned off and the LES is temporarily relaxed until the last of the distension is sensed. This results in an open LES and a lack of peristalsis until the very last of the liquid in succession comes through.

Question 25

How should you handle phase 2 of the triphasic cranial diabetes insipidus response?

Answer 25

Give 3% saline and monitor, monitor, monitor.

Do this relatively slowly (6-8 mEq/L/day) and only when the patient is symptomatic.

If patient is asymptomatic, just restrict fluid.